WEBVTT

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Prof: Now I've been
describing the intimate

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relationship between sex and
violence within the chimpanzee

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social system.

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This lecture,
and forever after,

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we shift our focus to humans,
and we want to ask what's

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stayed pretty much the same and
what has changed.

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Today I'm going to discuss two
topics, one: war in humans which

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hasn't changed all that much,
you can certainly see a

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continuity.

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Then I'm going to talk about
fecundity in humans,

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how many children we bear
compared to chimpanzees and

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you'll see there's a very big
difference there.

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The most obvious similarity and
one that gets the public quite

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excited is the similarity in--

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violent death has always been
very important aspect for humans

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especially--
well all the time,

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but I'm going to talk now about
what's called 'primitive times,'

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and this is data from a tribe
that's in Paraguay in South

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America in the period just
before it had real contact with

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Western people.

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So it has nothing to do with
modernity;

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this is apparently the way they
lived for time immemorial.

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What this table does is list
the number of deaths by age,

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putting them in different age
groups.

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Here are just children or we
would call them infants almost,

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0 to 3 years.

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You can notice there's a
significant amount of death;

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this is all illnesses;
that's communicable diseases

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and all kinds of other diseases;
that's the percentage of deaths

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from that,
and then there's other causes:

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congenital, degenerative,
accidents some,

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but here's violence--
various forms of violence.

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56% of infants from 0 to 3 died
because of violence.

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Here is children age 4 to 14
and again we see that all

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illnesses, about 15%,
accidents.

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Violence 74%.

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Now adults during--this is a 45
year period, the number of years

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in the periods are not equal,
and here is illness 28%,

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not insignificant;
accident, not insignificant,

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but the various forms of
violent deaths:

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46%, and it's only when you get
over 60 years of age--

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so in each of those three age
categories violent deaths have

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been the dominant form of death.

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It's separated by males and
females, males/females total,

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and that's true for males and
for females, I'm showing you the

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sum totals.

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It's only even after age 60
violent death is still the

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dominant cause,
a third of deaths,

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but it's the only age at which
it isn't --

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at least half of the deaths,
only when you get that old.

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It's quite striking how
significant violent death is in

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human demography.

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Several things should be
noticed there,

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that communicable diseases are
less important for

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hunter/gatherers;
these are very primitive

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hunter/gatherers,
the Ache.

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One of your readings is from
their own description of the way

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they live and the dangers that
they face--

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that communicable diseases are
less important because the

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population density is so low.

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Later we'll see--and so
diseases just don't get to pass

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around.

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We'll see later that the
influence of diseases rises

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drastically,
especially among infants,

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when the population density
gets high enough so that people

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pass around--
disease is quite common.

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Another thing you may notice
from this,

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that more individuals die in
the first 3 years of infancy,

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131 deaths than in the 45 years
of adulthood 126 deaths.

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So deaths in infancy are
50--per year are 15 times as

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common as deaths in adulthood.

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Of 383 people who are cataloged
here, only seven people died of

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old age.

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All of them had other really
identifiable causes.

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Given this background of the
significance of violence,

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and this includes more than
just war,

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but does not include deaths
from animals--

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being eaten by animals which is
considered an accident.

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Defining war,
going back to--we talked a lot

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about chimp--
you might call chimp war and

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now talk about human wars,
let's take a definition of war

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as the intentional killing of
members of one group by members

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of another group.

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The killing is done because
they are members of a group not

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because of any prior or
particular conflict between

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individuals.

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It's a group thing that
determines that the two sides

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that they're going to kill each
other.

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The human social system in
primitive times and in some

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politically correct circles,
you're not supposed to use the

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word 'primitive,' but I use it
in its original sense of living

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closer to the way humans did
millions-- thousands--many

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thousands or millions of years
ago.

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It's an early form of being
human.

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During that time we lived in
small tribal groups and they're

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multi-male groups,
(again we talked about most

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mammal's solitary males) with
strong male bonding,

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competition for status,
lots of inter-group conflict,

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competition for females and
violence against females.

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Everything that we know says
that humans have lived in

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communities with those
characteristics since as far

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back as we can --
know, and that is the same

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description you would apply to
chimpanzees.

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The archeological data shows
that through early farming times

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we lived in these small
dispersed settlements,

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and the average size seemed to
be in the same range as current

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chimpanzees, about 40
individuals.

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Size of communities range but
when you dig up these--the

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archeologists dig up these old
settlement they're in that

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ballpark.

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The anthropologists studying
currently alive people again

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find that the smallest organized
group of humans is a politically

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autonomous group consisting of
20 to 50 individuals with a head

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man.

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They call this--the proper
anthropological term is a band,

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again, basically the same size
as a chimp community.

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Among chimpanzees,
as I've described to you,

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inter-group violence is a
hit-and-run affair.

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With a small group of chimps
from one community,

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patrol their boundary;
they detect an isolated

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individual, a very small group,
or even better,

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a single individual in another
community, and then they attack.

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Anthropologists tell us that
primitive warfare has exactly

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the same characteristics.

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Among current primitive groups
the commonest form of combat is

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called raids and ambushes,
and communities are constantly

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engaging in this hit and run--
these hit and run raids on each

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other and they spring ambushes
to catch lone members of the

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other group.

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I lived for a while among
headhunters in Borneo.

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Presumably they weren't
headhunters anymore at that

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time,
and it was perfectly acceptable

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for them to go out and find a
child from a neighboring

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community--
same tribe, same everything,

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but the neighboring community--
playing by the river,

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catch him and take off his
skull and they had their

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attics--
were decorated with skulls.

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None of this was big--that
whole community fighting that

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whole community,
but little raids finding

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individuals,
didn't matter if it was child,

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adult,
nothing mattered like that.

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You can draw many similarities
between the chimp organization

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of this lethal raiding and human
warfare.

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How does one think about this?

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Well there are two
possibilities.

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Either whatever you think of
the chimp warfare and the causes

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of it you have to think that a
lot of that is still causing

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human warfare,
or you can say as many utopians

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do,
that they're different.

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That human--human warfare has
nothing to do with chimp

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warfare.

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One of the ways to prove or
disprove that would be to look

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in history,
as far as we can tell,

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and if it has different causes,
what you have to assume is,

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we know for sure that this is
what chimps do,

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and we presume that their
ancestors some millions of years

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ago before we split--
did that, but we don't really

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know that,
but we presume it's true that

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chimps did that and then
sometime in human history we

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have to find a period where we
stopped doing it.

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Then at a later period we
started doing it again but now

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for a totally different set of
reasons than for the chimp

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reasons.

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The strategy of trying to
figure out this question is then

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to go back in history and gather
the archaeological and the

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anthropological--
whatever data we can gather,

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and try to find out:
has there been a period in

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human history where we were
not--

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did not have this
inter-communal violence.

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The people who believe that war
has different causes --

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they think agriculture started
it because land becomes valuable

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or private property of some
sort,

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people wanted to get each
other's private property,

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or governments,
modern state governments,

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or very commonly you'll hear
that it has something to do with

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modernity,
that civilization has somehow

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corrupted the pure nature of
early humans who were wonderful

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human beings and didn't go to
war.

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What was the situation for
prehistoric humans?

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We can go back to the
Neanderthals,

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which are a sister subspecies,
and these guys as you know--

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heavy musculature,
robust bones--they were

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obviously strong characters.

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When you take--study their
graveyards, 40% of Neanderthal

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skeletons have head injuries.

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How does one attribute that?

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Either they were very clumsy
and accident prone and always

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somehow managed to fall on their
head--

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so far as we know they didn't
climb trees very much and hang

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upside down and fall,
or there was a lot of club

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wielding and head bashing going
on.

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Homo sapiens,
not Neanderthals,

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the earliest human burials that
haven't just decayed away are

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about 20,000 to 35,000 years ago
and when you dig them up what do

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you find?

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Spear points embedded in the
bones, cranial fractures,

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scalping marks,
and so forth.

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These burial grounds are found
wherever archeologists look.

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Some of the most prominent ones
are Italy, France,

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Egypt, Czechoslovakia because
that's where archeologists have

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had access to dig.

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At a 13,000 year old cemetery
in Sudan, over 40% of the

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skeletons had spear or arrow
points embedded in them.

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The wounds--there were children
buried there--the wounds found

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from the children in the
cemetery were all execution

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shots in the head or the neck.

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They were just bashed to death
in the head or the neck.

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This was not like one burial
from one horrific incident,

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it was used over several
generations.

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It was a continuing cemetery,
and many of the adults showed

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not only the wounds that caused
their death but many prior

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wounds,
bone cracks and skull cracks

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that had healed,
so you can see both a wound

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from some prior conflict which
had healed and the new wound

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which caused the death at this
moment.

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Individuals had gotten into a
lot of conflict:

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one skeleton had 20 different
wounds.

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That means bone cracks that you
could still see 13,000 years

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later, and soft tissue injury we
just don't have any way of

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knowing about.

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When you get to modern times,
still prehistoric,

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meaning before we have any
written records--

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before anything you'd call
civilization--

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things get a little stylized,
that clearly culture is

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advancing.

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There's a middle Stone Age cave
in Germany, only 5,000 to 10,000

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years old, where there are two
caches of skulls,

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just the skulls are there.

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They're neatly arranged like
eggs in a basket,

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and they are the disembodied
heads of men,

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women, and children with
multiple heads--

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multiple holes not by axes into
their skulls.

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I don't have--they didn't show
a picture of that,

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but this is a modern version of
it.

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This is actually from Thailand;
this is the way skulls can get

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arranged.

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This--that picture has a
totally different kind of

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purpose.

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How many of you remember ice
man?

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The guy that got unfrozen from
the Alps;

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you're all aware of this.

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In 1991, one of the glaciers in
the Alps disgorged this Stone

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Age man who had died they think
5,300 years ago.

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As at least a good number of
you know, he had a lot of press

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and he was called the ice man.

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Since it took 5,300 years for
him to come down the mountain,

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he must have died pretty high
up in some high point of the

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pass in the mountain,
so it was just assumed that he

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died--
froze to death--while trying to

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cross the Alps and got encased
in the ice and 5,000 years later

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came down.

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For ten years academic opinion
said that, and then they finally

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got around to taking a CAT scan
of the body.

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Guess what they found?

15:44.480 --> 15:48.830
A two centimeter flint
arrowhead had ripped through his

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scapula and lodged six
centimeters deep into his

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shoulder.

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He had been shot from behind by
an arrow and he died of internal

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bleeding.

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Again, a violent death.

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You come to even more recent
times,

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a Native American settlement,
American Indians from about

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1325 A.D.,
so almost 200 years before they

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have any contact with
westerners,

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and this contains the remains
of 500 men, women,

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and children.

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This is not a great picture,
but again,

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what you see that these victims
had been scalped,

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mutilated, and then something a
little unique,

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left exposed for a few months
to scavengers before being

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buried,
again, as a form of punishment,

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disrespect, or whatever.

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For the victim you not only
slaughter them,

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mutilate them,
maybe mutilate and then

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slaughter them,
and then you leave the

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scavengers to chew on them and
then finally they get buried.

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In short, archeology documents
warfare in every well-studied

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region for the past 10,000
years, which is when we have

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very good records.

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That's what you can dig up.

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The other thing is to look at
currently primitive human beings

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and ask how many of them are
truly peaceful.

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The anthropologists now take
over from the archeologists.

17:22.210 --> 17:26.410
What the anthropologists find
is that 90% to 95% of known

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societies have been involved in
war that we can document.

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One sample of 50 societies,
45 engaged in war frequently;

17:35.660 --> 17:40.190
4 did not engage in war because
they had recently been driven

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into isolated refuges by
warfare.

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Have any of you been to the
Aymara Indians in Lake Titicaca

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in Peru?

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It's a big tourist spot.

17:51.150 --> 17:53.180
There's an island in the middle
of Lake Titicaca,

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and they're very peaceful
people, they live on reeds,

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they don't have anybody to
fight.

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They were pushed off the
mainland by war and they've just

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been isolated,
so that's one of the groups

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that's-- well we haven't seen
them get into any wars but they

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have no possibility of it.

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One which is called 'peaceful,'
the Moonachie,

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which live actually in the
Sierra Nevada Mountains of

18:16.986 --> 18:20.446
California they say--
we'll call them peaceful

18:20.450 --> 18:23.810
because they only rarely go to
war.

18:23.808 --> 18:27.758
In another study 66% of
primitive societies went to war

18:27.756 --> 18:31.336
every year,
75% at least every two years,

18:31.336 --> 18:36.536
and up to 90% went to war at
least once every five years,

18:36.538 --> 18:41.488
so the evidence is mounting up
that so called primitive humans

18:41.490 --> 18:44.250
are not a terribly peaceful lot.

18:44.250 --> 18:48.270
The Dani tribes of New Guinea
had seven full battles and nine

18:48.265 --> 18:51.205
raids in one five and a half
month period.

18:51.210 --> 18:54.570
Some anthropologists was
sitting there for five and half

18:54.574 --> 18:57.454
months and that's the number
that he counted.

18:57.450 --> 19:01.780
One Yanomamo Village,
that's in Venezuela,

19:01.776 --> 19:05.466
was raided 25 times in 15
months.

19:05.470 --> 19:09.840
In the U.S. West,
86% of the Indian tribes went

19:09.835 --> 19:15.145
raiding or had to resist raids
at least once a year.

19:15.150 --> 19:18.320
Now you come to groups that are
usually peaceful,

19:18.318 --> 19:22.268
so there's a group in Malaysia
called the Semais and they were

19:22.272 --> 19:24.262
recruited so--
but during World War II,

19:24.262 --> 19:27.212
as you know,
the Japanese took Malaysia,

19:27.209 --> 19:32.699
and the British incited a sort
of guerilla movement against the

19:32.696 --> 19:36.176
Japanese;
so they were retained as scouts

19:36.183 --> 19:38.143
by the British to fight.

19:38.140 --> 19:42.590
I'm sorry this was later--this
was--they've--they were scouts

19:42.588 --> 19:46.888
to fight the guerilla insurgency
by supposed communists.

19:46.890 --> 19:50.300
Eventually some of the
guerillas killed a few of the

19:50.300 --> 19:52.320
Semais,
a few of their kinsmen,

19:52.318 --> 19:55.778
and then even though they had
never been known to be warlike

19:55.782 --> 19:57.722
they become extremely warlike.

19:57.720 --> 20:01.160
One Semai veteran recalled,
"We killed,

20:01.162 --> 20:04.292
killed, killed,
the Malays would rob the

20:04.285 --> 20:07.245
corpses, but we did not want
anything.

20:07.247 --> 20:09.887
We thought only of killing.

20:09.890 --> 20:10.370
Wah!

20:10.368 --> 20:14.928
Truly we were drunk with
blood."

20:14.930 --> 20:17.790
It sounds like their culture,
like many cultures,

20:17.788 --> 20:21.598
have repressed the killing
instinct,

20:21.598 --> 20:24.948
or killing propensity for one
reason or another,

20:24.950 --> 20:27.710
and then when the cultural
controls came off,

20:27.710 --> 20:31.670
boom, the instinct just roars
up, totally full blown,

20:31.670 --> 20:33.670
almost instantaneously.

20:33.670 --> 20:36.110
We've seen that in so many
cases.

20:36.108 --> 20:40.538
In Yugoslavia recently where
people lived together for a very

20:40.536 --> 20:43.926
long time in moderate harmony,
all of a sudden,

20:43.929 --> 20:46.879
bang, they start killing each
other.

20:46.880 --> 20:51.770
The Germans in the 19--before
the Depression in the 1920s--

20:51.769 --> 20:54.299
were among the most civilized
people on earth in science,

20:54.298 --> 20:57.558
and education,
boom, they become savages

20:57.556 --> 20:59.306
almost immediately.

20:59.308 --> 21:02.838
I think the indication is
there's something inside of us

21:02.839 --> 21:04.059
ready to pop out.

21:04.058 --> 21:07.568
Culture can repress it,
but demagogues know how to

21:07.565 --> 21:11.285
stick their finger into
populations and pull out that

21:11.285 --> 21:13.995
us/them and vilify the
"them"

21:14.003 --> 21:17.513
and bring us right back to
chimpanzee days.

21:17.509 --> 21:21.959
You all know Yale has a center
for study of the Cambodian

21:21.957 --> 21:25.177
genocide,
where now one group of people,

21:25.182 --> 21:29.352
the Cambodians,
sort of split into two and the

21:29.346 --> 21:31.646
slaughter was terrible.

21:31.650 --> 21:35.400
How many of you have seen the
movie The Killing Fields?

21:35.400 --> 21:38.560
How many of you know about the
Cambodian genocide?

21:38.558 --> 21:41.198
Again, most of you,
but not all of you;

21:41.200 --> 21:45.420
it's one of the most recent,
most horrific kinds of killing.

21:45.420 --> 21:51.060
This killing is--can be--what
basically happens is that one

21:51.060 --> 21:55.730
group does not consider another
group humans,

21:55.730 --> 21:57.260
and if you look in primitive
languages,

21:57.259 --> 22:01.049
very often the word for human
is the same as the word for

22:01.048 --> 22:03.618
their group whatever their group
is.

22:03.618 --> 22:07.928
In the American Indians that
was also a common kind of

22:07.932 --> 22:08.992
phenomenon.

22:08.990 --> 22:14.210
There's a good report from
March 18,1690 in Salmon Falls,

22:14.212 --> 22:18.322
New Hampshire,
where a girl named Mercy Short

22:18.317 --> 22:19.247
lived.

22:19.250 --> 22:22.130
They were raided by the Abenaki
Indians;

22:22.130 --> 22:26.600
that was at that time 1690,
a real frontier town.

22:26.598 --> 22:30.848
Mercy saw them kill her parents
and three of her brothers and

22:30.851 --> 22:31.561
sisters.

22:31.558 --> 22:34.558
She was taken to--on a long
winter march to Canada,

22:34.555 --> 22:37.605
and the captors sort of dragged
her up to Canada.

22:37.608 --> 22:41.288
During that March she saw a
five year old boy chopped to

22:41.285 --> 22:43.085
bits,
a young girl scalped,

22:43.093 --> 22:46.733
and was forced to watch with
her hands tied as another fellow

22:46.732 --> 22:49.652
captive was stripped,
bound to a stake,

22:49.645 --> 22:53.015
and tortured with fire,
after which the Abenaki

22:53.023 --> 22:55.503
"danced about him and at
every turn,

22:55.500 --> 22:59.500
they did with their knives cut
collops of his flesh,

22:59.500 --> 23:03.230
from his naked limbs,
and throw them with his blood

23:03.227 --> 23:04.417
into his face.

23:04.420 --> 23:07.270
Remember this is someone who is
already a captive with his hands

23:07.269 --> 23:08.989
tied so there's no immediate
threat.

23:08.990 --> 23:14.550
It's a clear sign of just not
considering these out-group

23:14.548 --> 23:16.928
individuals as humans.

23:16.930 --> 23:23.080
All chimpanzees have one set of
morals toward an in-group,

23:23.078 --> 23:25.838
and as I've told you,
that in the wild the male/male

23:25.835 --> 23:29.235
conflicts never result in death
nor do the male/female conflicts

23:29.239 --> 23:34.049
within a group,
but in an out-group if possible

23:34.045 --> 23:37.525
they always result in death.

23:37.529 --> 23:39.639
Now what does one think of this?

23:39.640 --> 23:45.480
There's a very interesting
story from early America,

23:45.480 --> 23:50.110
it's actually Amerigo Vespucci,
after whom America is named,

23:50.108 --> 23:53.268
and you know Columbus
discovered America in 1492.

23:53.269 --> 23:57.159
Ten years later they were
exploring all around and

23:57.157 --> 24:01.837
Vespucci went on a--one of the
exploration expeditions along

24:01.839 --> 24:04.299
the coast of South America.

24:04.298 --> 24:08.978
He had some interactions with
the local tribe's people and had

24:08.976 --> 24:11.196
some interpreters on board.

24:11.200 --> 24:14.930
Columbus had brought some
natives back to Europe,

24:14.929 --> 24:18.969
and they were able to do some
kind of translation.

24:18.970 --> 24:22.520
He was very interested in how
different they were from

24:22.516 --> 24:23.316
Europeans.

24:23.318 --> 24:26.838
"Their marriages are not
with one woman but with as many

24:26.840 --> 24:29.610
as they like,
and without much ceremony,

24:29.605 --> 24:33.815
meaning they just get married
very causally and we have known

24:33.818 --> 24:36.908
someone who had ten women
married to him.

24:36.910 --> 24:41.060
They are a very prolific
people, , but they have no heirs

24:41.056 --> 24:43.866
because they hold no
property."

24:43.868 --> 24:49.198
Even childbirth is without
pain, "Women in parturition

24:49.199 --> 24:52.599
do not use any ceremony as ours
do.

24:52.598 --> 24:55.638
They eat everything,
go on the same day to the

24:55.640 --> 24:59.490
fields and wash themselves;
it seems that they hardly feel

24:59.487 --> 25:01.057
their parturition."

25:01.058 --> 25:05.728
Parturition--giving birth--now
you can see that what he's

25:05.726 --> 25:10.386
dealing with in the 1500s,
the late renaissance attitude,

25:10.393 --> 25:12.813
political science theory.

25:12.808 --> 25:15.808
What is it that causes wars
between societies,

25:15.813 --> 25:18.153
which they had lots of back
then.

25:18.150 --> 25:24.410
One of the issues is original
sin, these are very religious

25:24.411 --> 25:30.891
people, and what was the major
punishment for Eve's eating of

25:30.887 --> 25:32.397
the apple?

25:32.400 --> 25:35.480
Pain in childbirth,
severe pain in childbirth;

25:35.480 --> 25:38.430
here were some people that had
no pain in childbirth,

25:38.433 --> 25:40.313
and he waxes poetic about that.

25:40.308 --> 25:43.518
Were they absolved of original
sin?

25:43.519 --> 25:46.989
That's the kind of issue that's
in his mind.

25:46.990 --> 25:50.530
He also says,
"They are people who lived

25:50.525 --> 25:52.875
many years,
and according to their

25:52.883 --> 25:56.193
succession, we have known many
men who have four generations

25:56.192 --> 25:57.092
living."

25:57.088 --> 25:59.728
So that's about 80 years--what
is he referring to here?

25:59.730 --> 26:03.220
Again, from the Bible;
the span of life,

26:03.221 --> 26:05.211
what's the span of life?

26:05.210 --> 26:09.100
70 years, very hard to fit four
generations into that,

26:09.102 --> 26:13.142
so again, he's reflecting that
these are not people like

26:13.141 --> 26:14.611
European people.

26:14.608 --> 26:17.948
He goes on with all the wonders
of their civilization,

26:17.954 --> 26:21.494
or their un-civilization
whatever you want to call it.

26:21.490 --> 26:24.780
But, he says,
"They are a warlike

26:24.779 --> 26:27.669
people,
and when they fight they do so

26:27.670 --> 26:30.630
very cruelly,
and that side which is lord of

26:30.627 --> 26:33.107
the battlefield bury their own
dead,

26:33.108 --> 26:36.498
but the enemy dead they cut up
and eat.

26:36.500 --> 26:42.050
One of their men confessed to
me that he had eaten the flesh

26:42.048 --> 26:45.058
of more than 200 bodies."

26:45.058 --> 26:48.568
Continuing, Vespucci talking,
"The most astonishing

26:48.565 --> 26:52.255
thing about their wars and
cruelty is that we could find no

26:52.260 --> 26:55.980
reason for them,
since they have no property or

26:55.976 --> 26:58.756
lords,
or kings, or desire for

26:58.758 --> 27:02.948
plunder, or lust to rule,
which seems to me to be the

27:02.948 --> 27:05.048
causes of war and
disorder."

27:05.048 --> 27:08.588
Again straight late renaissance
theory and political science

27:08.588 --> 27:09.128
theory.

27:09.130 --> 27:13.200
"When we asked them to
tell us the cause of the war and

27:13.204 --> 27:17.074
disorder they could give no
other reason except that this

27:17.073 --> 27:21.423
war began among them a long time
ago and they wish to avenge the

27:21.423 --> 27:23.983
death of their ancestors."

27:23.980 --> 27:30.390
It's a very interesting
passage, the Indians--

27:30.390 --> 27:33.630
Vespucci's idea is that
original sin is what causes this

27:33.625 --> 27:37.395
and then political--
the sins that humans do have

27:37.400 --> 27:42.350
the lust for power,
etc., is what causes all these

27:42.346 --> 27:48.206
wars and none of that fits these
South American Indians.

27:48.210 --> 27:51.780
The same message,
that -- it's not obvious what

27:51.775 --> 27:56.025
the cause of these wars is,
comes from modern anthropology,

27:56.029 --> 27:59.699
so the Yanomamo of Venezuela
and Brazil who are very violent

27:59.703 --> 28:02.723
people,
there was a book called The

28:02.715 --> 28:05.735
Fierce People that describes
them.

28:05.740 --> 28:07.780
They're very, very warlike.

28:07.778 --> 28:10.738
They're in that border between
Venezuela and Brazil;

28:10.740 --> 28:14.330
they're involved in almost
constant warfare and yet what

28:14.329 --> 28:15.439
are they after?

28:15.440 --> 28:18.160
Yanomamo villages are
surrounded by abundant

28:18.163 --> 28:19.623
unoccupied territory.

28:19.618 --> 28:22.338
They're just not settlement,
to settlement,

28:22.342 --> 28:24.932
to settlement,
there's plenty of space in

28:24.934 --> 28:26.754
which they could expand.

28:26.750 --> 28:28.530
Napoleon Chagnon,
who you may have heard of,

28:28.528 --> 28:31.058
the anthropologist who studies
the Yanomamo,

28:31.058 --> 28:34.848
believes that the fighting
between them was apparently

28:34.852 --> 28:39.362
motivated only by desires to
exact revenge and capture women.

28:39.358 --> 28:43.888
We seem to have come across
this before,

28:43.890 --> 28:47.430
but again, just as in
chimpanzees, in primitive

28:47.429 --> 28:51.969
warfare females are killed as
often as they are captured and

28:51.969 --> 28:56.739
most of these primitive tribes,
as well as modern people's,

28:56.737 --> 29:01.007
have difficulty getting food,
not as a cause of war but as a

29:01.009 --> 29:01.999
result of war.

29:02.000 --> 29:06.250
Things get so disrupted by war,
that's the reason they have

29:06.252 --> 29:07.942
trouble getting food.

29:07.940 --> 29:12.220
All of this is archeological
and anthropological,

29:12.222 --> 29:17.402
studying times or peoples who
don't have really any writing

29:17.397 --> 29:18.377
system.

29:18.380 --> 29:21.800
So in a sense it's prehistoric.

29:21.798 --> 29:30.098
Once we come to writing,
the record of violence flows

29:30.104 --> 29:32.664
hot and heavy.

29:32.660 --> 29:35.690
The first account of the
exploits of mortals is our

29:35.694 --> 29:36.974
military histories.

29:36.970 --> 29:39.870
The earliest writing of the
Chinese, of the Greeks,

29:39.873 --> 29:42.253
of the Romans,
are concerned with wars and

29:42.253 --> 29:43.303
warrior kings.

29:43.298 --> 29:47.528
Most Mayan hieroglyphic texts
are devoted to the genealogies,

29:47.525 --> 29:50.335
biographies,
and military exploits of the

29:50.343 --> 29:51.473
Mayan kings.

29:51.470 --> 29:54.390
The earliest Egyptian
hieroglyphics record the

29:54.394 --> 29:56.934
victories of Egypt's first
Pharaoh's.

29:56.930 --> 30:02.250
The first secular literature
written in cuneiform recounts

30:02.250 --> 30:06.730
the adventures of the warrior
king, Gilgamesh.

30:06.730 --> 30:09.920
The early and extreme
warlikeness of the earliest

30:09.922 --> 30:12.652
civilizations is laid out in the
Bible.

30:12.650 --> 30:16.330
You just read the Bible and you
get the whole message I'm giving

30:16.328 --> 30:16.678
you.

30:16.680 --> 30:20.730
The earliest written part of
the Old Testament,

30:20.733 --> 30:25.673
Exodus, recounts the brutal
Hebrew conquest of Canaan.

30:25.670 --> 30:30.920
Numbers 31:7-18,
The Israelites get the Ten

30:30.923 --> 30:32.803
Commandments.

30:32.799 --> 30:34.409
Thou shalt not kill.

30:34.410 --> 30:37.730
And then they go off to conquer
Canaan with lots and lots of

30:37.727 --> 30:38.287
killing.

30:38.288 --> 30:41.378
They waged war against the
Midianites as the Lord--

30:41.380 --> 30:44.830
this is one of my favorite
passages: "They waged war

30:44.830 --> 30:48.340
against the Midianites as the
Lord had commanded Moses and

30:48.344 --> 30:51.964
killed every male among them,
but the Israelites kept the

30:51.962 --> 30:54.502
women of the Midianites with
their children as

30:54.502 --> 30:55.522
captives."

30:55.519 --> 30:58.119
When Moses learned about this,
the captains came back,

30:58.117 --> 31:00.567
thumped their chests,
we've had a great victory;

31:00.568 --> 31:03.028
we've killed all the men and
here we have the women and

31:03.027 --> 31:05.257
children as captives,
Moses becomes angry:

31:05.255 --> 31:07.465
"So you've spared all the
women,

31:07.470 --> 31:11.810
why they are the very ones who
prompted the unfaithfulness of

31:11.810 --> 31:14.200
the Israelites toward the Lord.

31:14.200 --> 31:18.530
Slay therefore every male child
and every woman who has had

31:18.528 --> 31:22.608
intercourse with a man,
but you may spare and keep for

31:22.606 --> 31:26.446
yourselves all girls who have
had no intercourse with a

31:26.452 --> 31:27.382
man."

31:27.380 --> 31:32.410
An echo of the chimpanzees who,
when a female tries to transfer

31:32.414 --> 31:35.424
if she has children she's a
goner,

31:35.420 --> 31:37.200
if she's young,
presumably a virgin,

31:37.200 --> 31:40.960
then she will probably be
allowed to transfer.

31:40.960 --> 31:43.020
After the fall of Jericho the
Israelites,

31:43.019 --> 31:45.919
quote, "Put to the sword
all living creatures of the

31:45.923 --> 31:48.223
city,
men, women, young and old,

31:48.223 --> 31:52.303
as well as oxen,
sheep and asses."

31:52.298 --> 31:57.278
Next they attacked Ai,
"there fell that day a

31:57.276 --> 32:02.756
total of 12,000 men and women,
the entire population of

32:02.759 --> 32:04.079
Ai."

32:04.078 --> 32:05.718
The clear thing,
it's quite striking how this

32:05.723 --> 32:07.373
comes so soon after the Ten
Commandments,

32:07.368 --> 32:10.368
that what's clearly going on
is, just as chimps--

32:10.368 --> 32:12.028
is an in-group,
and clearly the Ten

32:12.031 --> 32:14.691
Commandments is --
intended for the in-group,

32:14.692 --> 32:17.542
'thou shalt not kill,' straight
chimpanzee.

32:17.538 --> 32:21.418
However, out-groups,
if you don't kill them all

32:21.423 --> 32:24.803
you're not obeying God's
commandments.

32:24.798 --> 32:32.658
In very modern times atrocities
continue with no lessening of

32:32.660 --> 32:39.470
the horrific nature of it
compared to chimps or early

32:39.471 --> 32:44.081
human beings,
and I'll describe one famous

32:44.075 --> 32:48.295
event to you which--
how many of you know about the

32:48.299 --> 32:49.739
rape of Nanking?

32:49.740 --> 32:52.810
Again, not all of you,
all of you should know these

32:52.808 --> 32:55.938
things that I refer to are very
important things.

32:55.940 --> 32:59.260
This is during World War II in
I think it was 1937.

32:59.259 --> 33:01.969
The Japanese were trying to
conquer China,

33:01.970 --> 33:04.610
and it was a big place and they
were getting rather frustrated

33:04.613 --> 33:06.503
because--
in Japan it's a small place,

33:06.503 --> 33:09.523
in China it's a huge place,
and it's not an easy thing to

33:09.516 --> 33:09.726
do.

33:09.730 --> 33:15.980
But they captured a city called
Nanking, south of the Yangtze

33:15.984 --> 33:16.824
River.

33:16.818 --> 33:20.818
In short order,
the Japanese slaughtered

33:20.817 --> 33:22.557
350,000 people.

33:22.558 --> 33:26.778
The total population of Nanking
at the time was only about

33:26.781 --> 33:30.931
650,000 and several hundred
thousand had already fled.

33:30.930 --> 33:34.190
In short, they basically killed
every Chinese that they could

33:34.192 --> 33:36.972
find, just like the Bible
stories, or the chimpanzee

33:36.967 --> 33:37.617
stories.

33:37.618 --> 33:41.238
A Japanese newspaper reporter
watched Chinese prisoners being

33:41.238 --> 33:43.648
bayoneted on the top of the city
wall.

33:43.650 --> 33:46.390
"One by one,
prisoners fell down into the

33:46.388 --> 33:49.598
outside of the wall,
blood splattered everywhere,

33:49.595 --> 33:53.135
the chilling atmosphere made
one's hair stand on end and

33:53.142 --> 33:55.272
limbs tremble with fear."

33:55.269 --> 33:58.229
This reporter is talking only
from Japanese and we'll see,

33:58.230 --> 34:01.170
Nazi sources because it's
possible the Chinese sources may

34:01.170 --> 34:05.060
be exaggerated or something,
but the belief is that neither

34:05.063 --> 34:09.043
the Japanese nor the Nazi
sources would exaggerate.

34:09.039 --> 34:11.479
Another Japanese military
correspondent,

34:11.478 --> 34:14.728
even more constrained,
described another locale where

34:14.728 --> 34:17.978
the murders were by
samurai-style decapitations.

34:17.980 --> 34:21.240
"Those in the second row
were forced to dump the severed

34:21.242 --> 34:24.562
bodies into the river before
they themselves were beheaded.

34:24.559 --> 34:28.259
The killing went on nonstop
from morning until night,

34:28.257 --> 34:32.307
but they were only able to kill
2,000 persons that way.

34:32.309 --> 34:34.709
The next day,
tired of killing in this

34:34.711 --> 34:37.051
fashion, they set up machine
guns.

34:37.050 --> 34:41.150
So great was the slaughter that
the Japanese general complained

34:41.154 --> 34:45.264
that he could not find ditches
deep enough to bury the enormous

34:45.257 --> 34:46.977
pile of corpses."

34:46.980 --> 34:49.740
Tens of thousands of Chinese
women were raped,

34:49.739 --> 34:53.229
often in schools and nunneries,
thousands more were put into

34:53.233 --> 34:56.733
sexual slavery,
forced into prostitution,

34:56.733 --> 35:01.413
and referred to in Japanese as
public toilets,

35:01.409 --> 35:04.809
the women forced into
prostitutions.

35:04.809 --> 35:08.739
Many soldiers went beyond rape
to disembowel women,

35:08.735 --> 35:12.815
slice off their breasts,
nail them alive to walls.

35:12.820 --> 35:16.030
Fathers were forced to rape
their daughters and sons their

35:16.027 --> 35:18.077
mothers;
not only did live burials,

35:18.079 --> 35:21.459
castration, and the carving of
organs and roasting of people

35:21.460 --> 35:24.060
become routine,
but more diabolical tortures

35:24.061 --> 35:27.031
were practiced like hanging
people from their tongues on

35:27.030 --> 35:29.930
iron hooks,
or burying people to their

35:29.925 --> 35:34.735
waists and watch them being torn
apart by German Shepherds.

35:34.739 --> 35:39.539
So sickening was the spectacle
that even the Nazi's in the city

35:39.543 --> 35:40.863
were horrified.

35:40.860 --> 35:44.430
When the Japanese took
Singapore, right after Pearl

35:44.432 --> 35:47.792
Harbor, they shot and
decapitated another 20,000

35:47.791 --> 35:48.651
Chinese.

35:48.650 --> 35:53.220
That was just a modern example
to show you that whatever this

35:53.219 --> 35:57.559
is in humans that makes us want
to kill members of another

35:57.561 --> 35:59.931
group,
it is totally unfettered by

35:59.931 --> 36:03.051
anything that you might call
control or civilization,

36:03.050 --> 36:07.940
when it breaks out the violence
is just incredible.

36:07.940 --> 36:12.800
The bottom line is that war
seems to be characteristic of

36:12.804 --> 36:17.934
almost all, and possibly all
human societies at all times in

36:17.929 --> 36:19.319
our history.

36:19.320 --> 36:22.640
There is no example,
no period which we can find

36:22.643 --> 36:24.743
out,
where there's a discontinuity

36:24.744 --> 36:28.014
between the chimpanzee behavior
and our current behavior,

36:28.010 --> 36:32.510
and so again,
I think whatever you think of

36:32.512 --> 36:36.482
what's causing the chimpanzee
war,

36:36.480 --> 36:41.180
you probably have to consider
very much the same explanation

36:41.184 --> 36:42.464
for human war.

36:42.460 --> 36:46.610
The amount of death--I showed
you one example from one tribe,

36:46.610 --> 36:50.250
the Ache in South America,
and any one tribe's experience

36:50.253 --> 36:52.533
may or may not be
characteristic.

36:52.530 --> 36:54.930
This is from a book,
Lawrence Keeley,

36:54.929 --> 36:58.659
War Before Civilization,
which traces a lot of the

36:58.664 --> 37:01.204
information I've been giving
you,

37:01.199 --> 37:04.509
and what he does is,
he collects all the data that

37:04.514 --> 37:09.014
anybody's ever collected,
so that he sort of can get some

37:09.007 --> 37:12.527
idea of the percentages of
deaths by war.

37:12.530 --> 37:15.320
This is percent of deaths from
warfare--

37:15.320 --> 37:18.680
this is males,
and this is everybody together,

37:18.679 --> 37:23.099
and these are different tribes
at different tribes for whom we

37:23.099 --> 37:23.969
have data.

37:23.969 --> 37:27.819
You'll see that the
numbers--the male numbers go up

37:27.822 --> 37:31.832
to 50% or 60% of male deaths are
from these wars,

37:31.829 --> 37:34.799
and the deaths of everybody
which is this,

37:34.800 --> 37:37.790
is somewhat smaller,
a fifth or a sixth,

37:37.789 --> 37:44.119
15% to 20% of deaths,
but going up of course to 40%

37:44.119 --> 37:45.639
of deaths.

37:45.639 --> 37:48.999
The point he's trying to make
with this graph is,

37:49.000 --> 37:53.870
here's primitive warfare,
these darkly colored bands,

37:53.869 --> 37:58.089
what he calls primitive
warfare, and the white bands are

37:58.094 --> 38:02.554
so called civilizations and he
calls civilizations anything

38:02.550 --> 38:06.610
that has a state,
like the Aztecs had a state in

38:06.612 --> 38:08.752
one of these it is Aztecs.

38:08.750 --> 38:13.110
From the data that one has we
are--

38:13.110 --> 38:16.660
even though we think of World
War II and all of these current

38:16.664 --> 38:20.284
and incredible wars and all our
technology devoted to war--

38:20.280 --> 38:24.750
what's happening is that we
have much--

38:24.750 --> 38:29.180
many, many more people die then
did in the past but the

38:29.177 --> 38:34.097
population of humans has grown
so much that the percentage is

38:34.096 --> 38:37.296
not so huge,
and that wars are less frequent.

38:37.300 --> 38:40.630
Rather than having raids almost
continuously as in a lot of

38:40.632 --> 38:43.812
primitive warfare,
we have wars every 15 or 20

38:43.806 --> 38:48.026
years or so in general between
any two groups fighting each

38:48.034 --> 38:48.694
other.

38:48.690 --> 38:52.150
What he shows,
again, from the data that has

38:52.152 --> 38:57.152
large and unknown error bars--
the civilized warfare which is

38:57.150 --> 39:00.220
the Aztecs,
France in the nineteenth

39:00.217 --> 39:03.877
century with Napoleonic War,
the 1870 War,

39:03.880 --> 39:08.180
Western Europe in the
seventeenth century lots and

39:08.177 --> 39:10.987
lots of wars in the 1600s,
U.S.

39:10.990 --> 39:12.720
and Europe in the twentieth
century,

39:12.719 --> 39:15.009
World War I and World War II
and so forth,

39:15.010 --> 39:20.980
that as far as he can tell the
fraction of all deaths that is

39:20.976 --> 39:23.956
caused by war is decreasing.

39:23.960 --> 39:28.280
One possible very nice way of
looking at human history is that

39:28.277 --> 39:31.177
humans have some sort of a
propensity,

39:31.179 --> 39:35.099
call it an instinct if you
like, to identify an in-group

39:35.103 --> 39:37.533
and everyone else is out-groups.

39:37.530 --> 39:39.720
These in groups can be
nationality, they can be

39:39.724 --> 39:42.594
religion, they can be color of
skin, they can be language.

39:42.590 --> 39:46.700
Language is a big source of
conflict in Canada and Belgium,

39:46.699 --> 39:49.529
all kinds of places;
almost anything will do.

39:49.530 --> 39:53.850
It can be Yale versus Harvard,
or Berkeley College versus

39:53.849 --> 39:56.009
Calhoun College,
and Red Sox,

39:56.010 --> 39:57.630
the Red Sox fans.

39:57.630 --> 39:59.590
The English who are generally
very civilized,

39:59.588 --> 40:02.348
get into a soccer stadium and
they start killing each other.

40:02.349 --> 40:06.929
Humans have this enormous
desire to identify in-group and

40:06.927 --> 40:07.907
out-group.

40:07.909 --> 40:12.029
We even now pay to advertise a
company,

40:12.030 --> 40:14.120
because anything that looks
like a group membership symbol,

40:14.119 --> 40:18.029
humans love that,
and will pay a lot to have a

40:18.025 --> 40:22.925
hat or a name of some team,
or even some company on them.

40:22.929 --> 40:28.219
We have very different morals
towards the in-group and the

40:28.224 --> 40:29.344
out-group.

40:29.340 --> 40:36.180
It seems that that's what's
still going on in us,

40:36.181 --> 40:41.171
that as time--we have that
still.

40:41.170 --> 40:43.380
But as time goes on,
because of increased

40:43.378 --> 40:46.358
communication and increased
education, probably what we

40:46.362 --> 40:48.132
consider the in-group grows.

40:48.130 --> 40:51.500
First it was your little
village, a little hamlet of 40

40:51.496 --> 40:53.776
people,
and then maybe organized into

40:53.782 --> 40:57.282
some sort of a tribe of 1,000
people and gradually it grows.

40:57.280 --> 40:59.340
If you read the history of
Europe there are all these

40:59.336 --> 41:01.876
little cities,
say Greece with city-states,

41:01.878 --> 41:04.948
a whole city could be
considered one family,

41:04.949 --> 41:07.659
with a lot of divisions within
it.

41:07.659 --> 41:11.409
Renaissance Italy you have the
Medici's and the Pazzi killing

41:11.407 --> 41:15.217
each other, families within
cities, but gradually it grows.

41:15.219 --> 41:17.799
You get nation states,
and as they grow,

41:17.800 --> 41:20.780
the wars get less because
people within say France don't

41:20.777 --> 41:22.887
generally have wars with each
other,

41:22.889 --> 41:25.149
but France will have a huge war
with Germany.

41:25.150 --> 41:27.530
The group that people consider
"us"

41:27.527 --> 41:29.887
gets larger,
the frequency of war goes down,

41:29.889 --> 41:32.889
but since you have so many
people fighting so many people,

41:32.889 --> 41:36.529
the war causes more and more
deaths.

41:36.530 --> 41:39.540
Possibly, this is optimistic,
that as we become more

41:39.536 --> 41:42.896
interconnected and we consider
more people "us,"

41:42.896 --> 41:44.836
and fewer people
"them,"

41:44.842 --> 41:47.792
that gradually this behavior
will disappear.

41:47.789 --> 41:52.349
But that's just guess work.

41:52.349 --> 41:56.539
Now Keeley, who gathered a lot
of this data,

41:56.536 --> 41:58.966
he has his own summary.

41:58.969 --> 42:02.629
Again, in frustration about not
really understanding …

42:02.634 --> 42:07.234
what these wars are all about,
he does not accept any idea

42:07.228 --> 42:10.568
that there's any biology
involved.

42:10.570 --> 42:13.490
He says, since he can
occasionally find some group

42:13.487 --> 42:16.997
that hasn't been to war for 20
years or something like that,

42:17.001 --> 42:18.731
then it can't be biology.

42:18.730 --> 42:22.170
The view of biology that many
social sciences have is sort of

42:22.166 --> 42:25.026
that --….--if it's
biology, it's a knee jerk

42:25.030 --> 42:25.660
reflex.

42:25.659 --> 42:28.679
If you're not--if your nervous
system is not impaired,

42:28.681 --> 42:32.271
every time I hit your knee with
a hammer your knee will kick out

42:32.273 --> 42:33.873
and there's no volition.

42:33.869 --> 42:38.149
They say if we ever see a human
not doing some behavior,

42:38.150 --> 42:41.110
that behavior cannot be
instinctual.

42:41.110 --> 42:46.170
Of course that was disproven in
around 1910 by Pavlov,

42:46.173 --> 42:48.853
you all know about Pavlov?

42:48.849 --> 42:51.869
He takes an instinct as basic
as eating,

42:51.869 --> 42:55.359
and a dog sees a piece of meat
and starts salivating,

42:55.360 --> 42:58.540
and then very rapidly he rings
a bell a minute before the dog

42:58.536 --> 43:01.606
sees the meat and the dog starts
salivating to the bell.

43:01.610 --> 43:07.820
Since 1910 at least we've known
that even the most basic

43:07.822 --> 43:14.602
behavior can be controlled by
something with as small a brain

43:14.597 --> 43:17.497
as a dog,
even though one would never say

43:17.503 --> 43:19.343
the dog does not have an eating
instinct,

43:19.340 --> 43:21.070
does not have a salivating
instinct,

43:21.070 --> 43:24.190
of course they do and yet dogs
can control it.

43:24.190 --> 43:28.690
I tell a story about my dog,
so a smallish white Samoyed,

43:28.690 --> 43:30.780
and I'm at work all day.

43:30.780 --> 43:33.740
I work long hours and so she's
at home all day and by the time

43:33.744 --> 43:35.694
I come home she's a little
frustrated.

43:35.690 --> 43:38.400
She's been cooped up,
and I'm a little frustrated.

43:38.400 --> 43:42.140
So what happens:
I get down on my hands and

43:42.137 --> 43:44.537
knees and I growl at her.

43:44.539 --> 43:49.179
She immediately picks up the
cue, she's snarling back at me,

43:49.179 --> 43:52.469
and then I swat her one,
a gentle swat but she gets--

43:52.469 --> 43:55.349
she snips back at my hand and
we go at it.

43:55.349 --> 43:56.549
We have a great time.

43:56.550 --> 44:00.890
Unfortunately my dog has died,
but we had a great time and in

44:00.889 --> 44:03.639
the course of these she's
snapping--

44:03.639 --> 44:07.089
she's aroused,
her hair is standing on end,

44:07.090 --> 44:10.910
her tail is straight up,
her fangs are showed,

44:10.909 --> 44:14.749
and she's snapping away at me
and I get,

44:14.750 --> 44:20.110
maybe--we do 20 minutes or so
maybe--

44:20.110 --> 44:24.750
at least 50 to 100 bites where
she actually wins.

44:24.750 --> 44:28.410
I win, I smack her,
she wins and--so what that

44:28.407 --> 44:33.287
means over the years I've had
many tens of thousands of times

44:33.286 --> 44:36.616
where she's grabbed me and all
that,

44:36.619 --> 44:39.409
and guess what,
not once in all those many

44:39.413 --> 44:42.823
thousands of bites has she ever
pierced my skin.

44:42.820 --> 44:44.780
All right, this is a peaceful
house dog;

44:44.780 --> 44:46.890
she doesn't know anything about
killing.

44:46.889 --> 44:48.339
No, not true.

44:48.340 --> 44:51.160
In the morning I take her out
running in the woods,

44:51.159 --> 44:53.079
I don't know if she takes me or
I take her,

44:53.079 --> 44:57.179
and if she sees a bird or a
squirrel,

44:57.179 --> 45:01.579
she's off and she comes back
with a dead bird in her mouth,

45:01.579 --> 45:03.049
clearly killed,
she clearly bit through their

45:03.052 --> 45:04.502
skin--
very, very proud,

45:04.496 --> 45:06.986
walking there with a dead
squirrel.

45:06.989 --> 45:08.829
Here's an animal and I love her
dearly,

45:08.829 --> 45:13.829
but her brain is not very big,
and she can get into the depths

45:13.826 --> 45:18.406
of real instinctual responses
and yet her brain is clever

45:18.413 --> 45:22.103
enough to be able to control it
and not--

45:22.099 --> 45:26.819
and to kill the squirrel but
not to kill me or not even break

45:26.822 --> 45:28.242
through my skin.

45:28.239 --> 45:31.399
I think the idea is a lot of
people think when you've

45:31.400 --> 45:35.230
described biological basis for
behavior that it's inevitable.

45:35.230 --> 45:38.970
The human species were lost,
we're never going to change,

45:38.969 --> 45:40.439
but that's nonsense.

45:40.440 --> 45:43.010
Humans are like chimpanzees,
we're quite intelligent,

45:43.010 --> 45:45.030
and we are capable--we have
instinct,

45:45.030 --> 45:47.450
I believe that we have
instincts for sure,

45:47.449 --> 45:51.049
you'll see it come out in the
most horrible ways and in some

45:51.047 --> 45:54.587
good ways,
but it's not that difficult to

45:54.585 --> 45:55.405
control.

45:55.409 --> 45:58.939
My dog can do it,
you guys can do it.

45:58.940 --> 46:02.490
The other issue which--these
are good topics for discussion

46:02.494 --> 46:06.504
in the sections--
is, some people also say when I

46:06.503 --> 46:10.083
describe duck rape or orangutan
rape,

46:10.079 --> 46:13.869
that some of--my describing it
and saying that animals do it

46:13.873 --> 46:15.163
I'm justifying it.

46:15.159 --> 46:18.589
There's this whole thing now
that what's natural is good and

46:18.585 --> 46:21.715
what animals do is natural and
therefore it's good,

46:21.719 --> 46:25.189
and it slops over to foods and
everything.

46:25.190 --> 46:32.610
This whole idea of natural law,
that you can tell from nature

46:32.614 --> 46:40.044
what is good and what is bad is
not to be taken seriously.

46:40.039 --> 46:44.699
That finishes that topic,
and I think you've had enough

46:44.699 --> 46:45.649
violence.

46:45.650 --> 46:50.630
I want to skip--switch to the
opposite side now.

46:50.630 --> 46:52.840
Demography is,
of course, births and deaths;

46:52.840 --> 46:55.910
those are the two main things
in demography.

46:55.909 --> 46:59.369
We have been talking about one
of the main causes of human

46:59.373 --> 47:02.273
death on one side,
and we find that there is a

47:02.268 --> 47:05.208
clear continuity between
chimpanzees and humans.

47:05.210 --> 47:08.770
Now let's talk about the other
side, births and there

47:08.769 --> 47:11.169
surprisingly,
humans are drastically

47:11.166 --> 47:13.286
different from chimpanzees.

47:13.289 --> 47:15.469
How do we know this?

47:15.469 --> 47:19.449
Chimpanzees were never very
successful demographically.

47:19.449 --> 47:22.599
At their peak there may have
been two million chimpanzees.

47:22.599 --> 47:27.879
A very small Chinese city is
two million individuals,

47:27.880 --> 47:32.480
and now because of the rise of
humans they're taking over their

47:32.483 --> 47:35.103
territory,
the guess is they've been

47:35.101 --> 47:41.981
reduced to about 100,000;
5% of their peak population.

47:41.980 --> 47:43.610
They are restricted to central
Africa;

47:43.610 --> 47:47.750
they have never spread beyond
central Africa.

47:47.750 --> 47:49.880
Humans, on the other hand as
you know, number in the

47:49.880 --> 47:52.510
billions;
we've spread to the farthest

47:52.510 --> 47:57.240
corners of the earth from the
ice cap around the North Pole to

47:57.240 --> 47:59.800
the hottest desert and jungle.

47:59.800 --> 48:04.710
There are tens of thousands of
times as many people,

48:04.710 --> 48:08.430
humans, as there are
chimpanzees, and humans have

48:08.427 --> 48:12.997
become absolutely dominant
basically everywhere on earth.

48:13.000 --> 48:16.690
From a demographic point of
view, maybe the first question

48:16.693 --> 48:19.413
we should ask,
why are there so many humans

48:19.414 --> 48:20.844
and so few chimps?

48:20.840 --> 48:25.790
What is the secret of our
demographic success?

48:25.789 --> 48:28.949
Let me give you a clue about
the time scale.

48:28.949 --> 48:35.069
We separated from chimps about
six million years ago,

48:35.065 --> 48:40.825
and I've shown you--this is
another version of the

48:40.827 --> 48:44.707
deaths--don't worry about it.

48:44.710 --> 48:48.730
Remember this--the family tree
here,

48:48.730 --> 48:53.440
and here is the split point
where humans branched off from

48:53.436 --> 48:58.056
chimps and bonobos and its
ballpark six million years ago

48:58.061 --> 48:59.881
that we split off.

48:59.880 --> 49:03.010
The population size,
what is believed,

49:03.010 --> 49:08.800
that the population size of
all--the group that became these

49:08.800 --> 49:14.690
three species was only about
50,000 individuals at this split

49:14.688 --> 49:15.668
point.

49:15.670 --> 49:22.230
That comes from the genetics,
the variation in genetics.

49:22.230 --> 49:26.640
This small group branched off
and started behaving--evolving

49:26.643 --> 49:28.143
quite differently.

49:28.139 --> 49:33.079
What happens when you have a
small group to begin with of

49:33.077 --> 49:37.407
50,000 breeding individuals,
then a small group breaks off

49:37.405 --> 49:40.815
and they may further subdivide
into smaller groups that may not

49:40.815 --> 49:43.065
come much in contact with each
other,

49:43.070 --> 49:46.430
you have inbreeding,
and inbreeding causes a lot of

49:46.434 --> 49:50.304
genetic problems,
but it also allows evolution to

49:50.304 --> 49:51.694
go very rapidly.

49:51.690 --> 49:54.230
For mutation,
if it is beneficial it appears,

49:54.230 --> 49:57.330
it can spread to a small
population very rapidly whereas

49:57.333 --> 50:00.323
it's extremely difficult for it
to spread into a large

50:00.322 --> 50:01.172
population.

50:01.170 --> 50:05.900
The tinyness of the number of
our human ancestors allowed a

50:05.898 --> 50:10.948
rather rapid evolution away from
the other groups who were also

50:10.954 --> 50:16.014
evolving of course because they
were also in small groups.

50:16.010 --> 50:22.770
That--at the split you start
going down this pathway and it's

50:22.768 --> 50:27.158
shown here as a single line,
but as all of you know from the

50:27.161 --> 50:28.491
newspaper,
there are many,

50:28.494 --> 50:32.364
many species splitting off at
different times with different

50:32.364 --> 50:34.994
characteristics all in the
humanoid,

50:34.989 --> 50:40.869
hominid line and by chance all
of those other species went

50:40.871 --> 50:43.041
extinct except one.

50:43.039 --> 50:45.739
That's another characteristic:
if you're a small group then

50:45.737 --> 50:47.177
it's very easy to go extinct.

50:47.179 --> 50:54.589
And all of the--we know 20,30
other humanoid species,

50:54.585 --> 50:59.425
and all went extinct except
one.

50:59.429 --> 51:01.669
The genus Homo,
which is the group of species

51:01.670 --> 51:04.010
in which we sit,
originates about two and a half

51:04.012 --> 51:06.842
million years ago,
and they start calling

51:06.842 --> 51:11.872
skeletons Homo sapiens
about a half a million years

51:11.873 --> 51:13.993
ago,
but even though they're Homo

51:13.994 --> 51:16.274
sapiens their brains are,
at that time,

51:16.268 --> 51:19.038
significantly smaller than ours
are now,

51:19.039 --> 51:24.349
and anatomically modern humans
date only from about 100,000 to

51:24.349 --> 51:26.089
150,000 years ago.

51:26.090 --> 51:30.110
All during this period the
number of humans was clearly

51:30.110 --> 51:31.080
very small.

51:31.079 --> 51:36.359
It's very humbling to realize
that with a small group that's

51:36.360 --> 51:39.470
evolving rapidly,
which means it's not yet

51:39.472 --> 51:42.012
mastered it's environment
because you don't--

51:42.010 --> 51:46.710
once you have optimized your
relationship to your environment

51:46.710 --> 51:50.130
evolution slows down,
but if we're evolving rapidly

51:50.132 --> 51:52.212
that means we haven't yet
mastered it.

51:52.210 --> 51:55.260
So a small group struggling in
its environment,

51:55.255 --> 51:58.905
very likely to go extinct;
most of our sibling species

51:58.909 --> 52:01.799
went extinct,
and I think with a very small

52:01.800 --> 52:05.970
role of the dice differently the
line towards humans could easily

52:05.971 --> 52:07.341
have gone extinct.

52:07.340 --> 52:13.320
It seems that about 100,000
years ago there was a bottleneck

52:13.315 --> 52:18.295
in the growth of human species,
and the humans living at that

52:18.297 --> 52:19.967
time,
a small group,

52:19.972 --> 52:24.442
were the ancestors to all
current human beings.

52:24.440 --> 52:28.240
There was a small population of
about 2,000 to 10,000 they

52:28.237 --> 52:30.447
believe,
and that the total human

52:30.454 --> 52:33.544
population,
from 2,000 to 10,000 of humans

52:33.541 --> 52:36.281
living in Africa and
interbreeding.

52:36.280 --> 52:39.590
There may have been other human
populations somewhere else that

52:39.592 --> 52:40.342
disappeared.

52:40.340 --> 52:43.840
We don't know,
and the numbers 2,000 to 10,000

52:43.835 --> 52:47.095
some research puts them a few
times higher,

52:47.099 --> 52:51.449
we don't really know,
but again a very small number.

52:51.449 --> 52:54.509
We know from that period that
there was no substantial

52:54.507 --> 52:57.487
population growth,
so that means the average

52:57.490 --> 53:01.880
number of surviving children was
two or maybe teensy weensy bit

53:01.882 --> 53:05.562
higher then two,
so that meant when you have on

53:05.559 --> 53:09.919
average two children per couple,
that means that most lineages

53:09.923 --> 53:13.233
have died out,
that most individuals who were

53:13.230 --> 53:17.240
living at that time of this
small number now leave no

53:17.235 --> 53:18.925
descendants at all.

53:18.929 --> 53:22.609
If you trace back,
the genetics suggest that all

53:22.608 --> 53:25.968
current humans,
all races all over the world

53:25.974 --> 53:29.814
are the descendants of a single
human female.

53:29.809 --> 53:33.319
That every other line,
from the time when she was

53:33.318 --> 53:36.458
alive has died out,
and similarly for males,

53:36.461 --> 53:40.411
we are all the descendants of a
single human male.

53:40.409 --> 53:44.359
All other lines have died out,
and those two didn't have to

53:44.356 --> 53:45.986
live at the same time.

53:45.989 --> 53:48.259
In fact, almost certainly did
not live at the same time;

53:48.260 --> 53:52.450
it's just the randomness of
lines dying out and the genetics

53:52.445 --> 53:56.275
tells us that we know the rate
at which DNA mutates and

53:56.277 --> 53:59.577
diverges and so we--
and we know the range of a

53:59.579 --> 54:03.209
variation in current humans so
we just sort of narrowed that

54:03.208 --> 54:07.508
back and it goes back to this--
what did I say 100,000 years

54:07.514 --> 54:07.914
ago.

54:07.909 --> 54:13.569
That's the genetic Eve and the
genetic Adam that the newspapers

54:13.572 --> 54:18.872
just love this story but it's
just a common result of --

54:18.869 --> 54:21.949
a population that doesn't have
a lot of surviving children--

54:21.949 --> 54:24.119
lines are going to die out.

54:24.119 --> 54:27.029
You can read that the royal
houses of Europe is where you're

54:27.025 --> 54:28.005
all exposed to it.

54:28.010 --> 54:31.100
Look how few generations the
royal houses last before they

54:31.099 --> 54:33.949
don't have any heirs,
and that's in modern--these are

54:33.952 --> 54:36.812
the richest people at their time
and have all the food and

54:36.809 --> 54:39.759
protection and everything that
they want and they can't stay

54:39.764 --> 54:41.924
going for more than a few
generations.

54:41.920 --> 54:47.160
In primitive times,
the rate of extinction of lines

54:47.161 --> 54:48.421
was great.

54:48.420 --> 54:52.370
About 50,000 years ago--we're
going to spend a few million

54:52.369 --> 54:55.489
years in Africa,
then about 50,000 years ago a

54:55.489 --> 54:58.469
group of humans migrated out of
Africa.

54:58.469 --> 55:02.429
Again, the numbers and the
times, some people say it was as

55:02.427 --> 55:05.837
late as 25,000 years ago that
they migrated out.

55:05.840 --> 55:09.800
Then amazing things happened,
once they burst out on the rest

55:09.797 --> 55:12.367
of the world,
they spread everywhere.

55:12.369 --> 55:14.839
Humans are found everywhere on
the Eurasian continent,

55:14.840 --> 55:22.590
that's from Siberia to Spain by
about 20,000 years ago,

55:22.590 --> 55:26.890
and then from Siberia they
crossing the Bering Strait,

55:26.889 --> 55:29.639
which was a land bridge at that
time,

55:29.639 --> 55:33.129
and expanded into the Americas
and reached the very tip of

55:33.126 --> 55:35.326
South America by 10,000 years
ago.

55:35.329 --> 55:40.059
In 40,000 years which is a
blink of an eye in evolutionary

55:40.056 --> 55:44.536
terms, humans spread everywhere
on earth, an incredible

55:44.536 --> 55:46.606
population explosion.

55:46.610 --> 55:49.590
This is the first and greatest
explosion, a population

55:49.585 --> 55:50.815
explosion of humans.

55:50.820 --> 55:55.180
You should note that something
was making us superior at that

55:55.184 --> 55:59.844
time, and clearly it has nothing
to do with modern technology.

55:59.840 --> 56:05.590
All of this fantastic expansion
even pre-dates the invention of

56:05.594 --> 56:11.074
agriculture and most of what we
consider civilization starts

56:11.070 --> 56:13.020
with agriculture.

56:13.018 --> 56:17.528
What is the main difference
that has allowed this story that

56:17.534 --> 56:21.364
humans have done this and chimps
have done this?

56:21.360 --> 56:24.910
Well you ask,
what is the reproductive rate

56:24.911 --> 56:26.351
of chimpanzees?

56:26.349 --> 56:30.739
Well I've told you that a chimp
mother has one young every five

56:30.735 --> 56:34.175
to eight years,
so at that rate it's going to

56:34.177 --> 56:37.537
be very hard to increase at any
great speed.

56:37.539 --> 56:40.419
Human females have babies much
more frequently,

56:40.420 --> 56:42.800
it's quite possible to have a
baby every year,

56:42.800 --> 56:46.130
or every year and a half,
or two years,

56:46.130 --> 56:51.380
and this is common--my brother
was born 20 months apart from

56:51.375 --> 56:51.815
me.

56:51.820 --> 56:56.720
How many of you have siblings
less than two years apart?

56:56.719 --> 56:57.749
Most of you.

56:57.750 --> 57:02.850
So humans are quite capable of
doing something that chimps just

57:02.851 --> 57:03.841
cannot do.

57:03.840 --> 57:09.030
They have a rate of
reproduction of about four or

57:09.034 --> 57:12.394
five times slower than we do.

57:12.389 --> 57:14.669
The mothers,
the chimp mothers cannot take

57:14.666 --> 57:16.886
care of more than one young at a
time.

57:16.889 --> 57:20.109
They will have a young that's
clinging to them and then

57:20.108 --> 57:23.558
perhaps an adolescent son or
daughter with them but they'll

57:23.563 --> 57:26.163
never--
you never see two infants at a

57:26.157 --> 57:30.657
time,
whereas, humans can easily take

57:30.659 --> 57:34.709
care of two infants at a time.

57:34.710 --> 57:36.180
Twins in chimps?

57:36.179 --> 57:41.039
I have never heard--read
anything about chimps occurring

57:41.041 --> 57:46.261
in--twins occurring in chimps,
and I don't know whether they

57:46.259 --> 57:47.319
ever do.

57:47.320 --> 57:50.840
It may be just that we don't
have enough observation that

57:50.836 --> 57:54.476
maybe occasionally chimp twins
do happen, but it's not been

57:54.481 --> 57:56.241
reported that I've seen.

57:56.239 --> 57:59.359
Anybody take a--
Student:  Not about

57:59.360 --> 58:01.640
twins, I was just going to ask
if that's regulated by hormones

58:01.637 --> 58:02.157
completely.

58:02.159 --> 58:06.849
Like you would say that
lactation stops--

58:06.849 --> 58:07.779
Prof: Yes.

58:07.780 --> 58:11.550
Student:  But it's a
chimp is nursing a baby for five

58:11.547 --> 58:12.057
years?

58:12.059 --> 58:13.589
Prof: They're nursing
them for a long time.

58:13.590 --> 58:17.440
I don't recall what the number
is, but there's many behavioral

58:17.438 --> 58:18.258
mechanisms.

58:18.260 --> 58:20.900
So in nursing,
the actual physical stimulation

58:20.898 --> 58:25.058
of the nipple releases hormones,
Oxytocin, which prevents

58:25.057 --> 58:27.937
ovulation again,
and that can be prolonged for

58:27.940 --> 58:29.960
quite a period of time but is
not absolute,

58:29.960 --> 58:32.530
so there are other behavioral
mechanisms,

58:32.530 --> 58:35.750
other internal hormonal
mechanisms which ensure this and

58:35.750 --> 58:38.030
in chimpanzees we--
it's very hard to capture a

58:38.025 --> 58:39.765
chimp and do the physiology and
experiment,

58:39.768 --> 58:45.758
so we basically probably don't
know most of the answer to that

58:45.759 --> 58:46.839
question.

58:46.840 --> 58:53.120
The--a major difference --
between humans and chimps is a

58:53.121 --> 58:57.721
tremendous increase in human
fecundity.

58:57.719 --> 59:01.909
Now in demography we use the
word--fecundity means the

59:01.913 --> 59:04.053
ability to have children.

59:04.050 --> 59:08.090
Fertility means the number of
children you actually have,

59:08.090 --> 59:10.690
and that comes from French
usage and French use the word

59:10.688 --> 59:13.568
sort of oppositely to the way we
do and demography was born in

59:13.570 --> 59:14.090
France.

59:14.090 --> 59:18.330
When I say fertility I don't
mean the ability to have

59:18.331 --> 59:20.321
children,
that's fecundity,

59:20.317 --> 59:23.517
but I mean the number of
children that any given set of

59:23.516 --> 59:24.876
women actually have.

59:24.880 --> 59:31.500
We have to ask ourselves what
evolutionary factors allowed

59:31.496 --> 59:34.626
this change in fecundity.

59:34.630 --> 59:40.490
What limited chimp population,
what limited chimp fecundity?

59:40.489 --> 59:45.389
Well in primate evolution the
main factor is the time that

59:45.385 --> 59:47.615
brain development takes.

59:47.619 --> 59:50.399
A body that's capable of
walking and chewing and so forth

59:50.404 --> 59:53.094
can develop rather rapidly in
all kinds of animals,

59:53.090 --> 59:55.760
develop in a very short time
scale and are immediately

59:55.757 --> 59:58.837
capable of doing those things,
but if you're going to have a

59:58.838 --> 1:00:03.188
species with a big brain,
that's a slow process.

1:00:03.190 --> 1:00:07.280
In all the higher brain--the
bigger brain primates,

1:00:07.280 --> 1:00:10.390
the slow thing is brain
development.

1:00:10.389 --> 1:00:15.619
In order to not have to carry
this baby like for--

1:00:15.619 --> 1:00:18.979
until the brain is mature at
age 13 or something--

1:00:18.980 --> 1:00:22.130
they say we don't really
progress beyond adolescents--

1:00:22.130 --> 1:00:26.960
so in humans and great apes the
baby is born with physically

1:00:26.963 --> 1:00:31.883
somewhat mature but the brain is
still growing enormously.

1:00:31.880 --> 1:00:35.300
Really there's post-natal
development of the brain,

1:00:35.295 --> 1:00:39.385
so even at the nine months of
pregnancy, we're not at the end

1:00:39.394 --> 1:00:42.064
of the period of brain
development.

1:00:42.059 --> 1:00:46.889
The brain is nowhere near its
final size or complexity.

1:00:46.889 --> 1:00:53.829
That limits the rate at which
one can have childbirth and

1:00:53.833 --> 1:01:00.533
because the infant is born in
chimps and in humans,

1:01:00.530 --> 1:01:05.000
is born incapable of taking
care of itself,

1:01:05.000 --> 1:01:10.970
the mother has to stay with the
child and take care of it.

1:01:10.969 --> 1:01:15.409
In chimps the mother stays
exclusively with her infant for

1:01:15.411 --> 1:01:16.661
several years.

1:01:16.659 --> 1:01:20.719
The chimps get very little,
as I mentioned,

1:01:20.717 --> 1:01:25.837
very little in the way of
resources from the males.

1:01:25.840 --> 1:01:28.500
They mostly watch and they
do--they don't come in contact

1:01:28.500 --> 1:01:31.510
with males all that much,
they and their young forage by

1:01:31.510 --> 1:01:33.070
themselves,
and etc., etc.,

1:01:33.065 --> 1:01:34.985
and the males are just
patrolling.

1:01:34.989 --> 1:01:38.299
They see them every so often
and the males protect the

1:01:38.297 --> 1:01:39.107
boundaries.

1:01:39.110 --> 1:01:43.070
In terms of taking care of the
young the males basically have

1:01:43.065 --> 1:01:44.445
no role whatsoever.

1:01:44.449 --> 1:01:49.069
As a result of this need to
have intense care of the young,

1:01:49.070 --> 1:01:51.790
and no help from anyone,
sometimes other females will

1:01:51.791 --> 1:01:54.141
help,
but basically no help at all,

1:01:54.141 --> 1:01:57.541
the period in which the mother
has to devote herself

1:01:57.536 --> 1:02:00.996
exclusively to that one young is
quite prolonged.

1:02:01.000 --> 1:02:04.290
Now in humans,
males do play some more

1:02:04.286 --> 1:02:07.216
intimate part in child rearing.

1:02:07.219 --> 1:02:09.989
Not anywhere near as much as a
female but they do bring

1:02:09.985 --> 1:02:10.595
resources.

1:02:10.599 --> 1:02:13.829
In general, in most human
societies over time,

1:02:13.829 --> 1:02:17.779
males are responsible for
bringing some resources to the

1:02:17.777 --> 1:02:20.647
female on a rather continuing
basis.

1:02:20.650 --> 1:02:23.610
We don't really know how this
evolved because these things you

1:02:23.608 --> 1:02:25.838
can't really tell these things
from fossils.

1:02:25.840 --> 1:02:30.430
What we know is that
Africa--the chimps started in

1:02:30.432 --> 1:02:35.682
the jungle and then Africa
started drying out and so some

1:02:35.681 --> 1:02:39.591
subset of the chimps,
maybe pushed out by stronger

1:02:39.594 --> 1:02:41.494
individuals or clever
individuals,

1:02:41.489 --> 1:02:46.639
were pushed into this drying
out grasslands where there was

1:02:46.635 --> 1:02:49.915
less cover and less fruiting
trees.

1:02:49.920 --> 1:02:54.210
Dry land doesn't produce the
big fruiting trees that chimps

1:02:54.210 --> 1:02:55.100
depend on.

1:02:55.099 --> 1:02:59.269
As a difference between chimps
and bonobos, when there's a

1:02:59.268 --> 1:03:03.288
lesser food density the
population has to spread out.

1:03:03.289 --> 1:03:06.029
That if an individual is going
to find any food they're not

1:03:06.032 --> 1:03:08.022
going to find enough for a large
group,

1:03:08.018 --> 1:03:12.748
so individual females would
have to go forage quite

1:03:12.750 --> 1:03:13.980
separately.

1:03:13.980 --> 1:03:18.250
You can speculate further that
as the females spread out,

1:03:18.250 --> 1:03:21.930
the dominant males could no
longer keep watch over and

1:03:21.934 --> 1:03:26.504
control over these females,
they were just too far spread

1:03:26.501 --> 1:03:27.871
geographically.

1:03:27.869 --> 1:03:33.789
While in chimps--while the male
or female may go off for a short

1:03:33.789 --> 1:03:37.539
time period,
in what's called a consortship

1:03:37.539 --> 1:03:40.659
and there may be matings at that
time,

1:03:40.659 --> 1:03:44.829
there's no lasting,
no continuing relationship

1:03:44.827 --> 1:03:48.807
between any particular male and
a female.

1:03:48.809 --> 1:03:50.419
Chimpanzees,
as I mentioned,

1:03:50.418 --> 1:03:53.748
are male bonded and they spend
more time with each other,

1:03:53.753 --> 1:03:56.083
male to male,
than the males do with the

1:03:56.076 --> 1:03:56.906
females.

1:03:56.909 --> 1:03:59.829
In humans of course we still
have a lot of what they call

1:03:59.833 --> 1:04:01.753
male/male bonding,
military units,

1:04:01.751 --> 1:04:03.231
sport teams,
all male clubs,

1:04:03.228 --> 1:04:06.128
football, pre-wedding parties,
watching football,

1:04:06.130 --> 1:04:10.540
watching parties,
etc., but we've evolved in the

1:04:10.541 --> 1:04:15.141
direction of much more
male/female interaction and

1:04:15.143 --> 1:04:16.273
contact.

1:04:16.269 --> 1:04:19.489
Female sexuality changed.

1:04:19.489 --> 1:04:22.289
While chimpanzees always mate
from behind,

1:04:22.289 --> 1:04:25.279
humans engage in frontal
copulation,

1:04:25.280 --> 1:04:29.160
and since the face is how
humans and also chimpanzees

1:04:29.155 --> 1:04:32.465
detect each other--
they know individuals largely

1:04:32.469 --> 1:04:35.489
by their facial structure--
and they detect emotions,

1:04:35.492 --> 1:04:38.482
it's a very important part of
communication to detect the

1:04:38.480 --> 1:04:41.360
emotions and respond to each
other by facial cues--

1:04:41.360 --> 1:04:44.610
so this face to face
interaction, especially in the

1:04:44.614 --> 1:04:48.134
intensity of the sexual
encounter is considered a large

1:04:48.130 --> 1:04:51.320
part of the evolution of
male/female bonding.

1:04:51.320 --> 1:04:55.280
I forgot to show you last time,
but it's an excuse to show you

1:04:55.275 --> 1:05:00.355
this time,
here is a bonobo engaging in

1:05:00.360 --> 1:05:04.850
front to front sex,
male and female here,

1:05:04.846 --> 1:05:06.086
and she's grinning.

1:05:06.090 --> 1:05:09.390
She's clearly being pretty
happy about this,

1:05:09.393 --> 1:05:13.853
and I also said I would show
you--this is two females doing

1:05:13.849 --> 1:05:15.309
the same thing.

1:05:15.309 --> 1:05:18.219
If you didn't--if I didn't tell
you it was--this was two females

1:05:18.215 --> 1:05:19.825
you wouldn't know the
difference.

1:05:19.829 --> 1:05:23.579
Unless you're watching you can
see that they both have their

1:05:23.579 --> 1:05:27.329
swellings, that's how you tell
that they are two females.

1:05:27.329 --> 1:05:31.709
I mean the guys who took the
picture obviously knew a lot

1:05:31.713 --> 1:05:36.413
more but you can tell that--so
this is what I described--that

1:05:36.411 --> 1:05:38.841
the locals call hoka,
hoka.

1:05:38.840 --> 1:05:44.800
This whole evolution of
sexuality in the human line,

1:05:44.800 --> 1:05:47.980
the clitoris has moved forward
for--

1:05:47.980 --> 1:05:51.570
which in face-to-face
copulation probably makes it--

1:05:51.570 --> 1:05:58.360
more female pleasure during the
act of copulation and therefore

1:05:58.362 --> 1:06:01.872
again reinforces this bonding.

1:06:01.869 --> 1:06:10.319
Another big difference and this
is not an extreme case of the

1:06:10.322 --> 1:06:14.412
rump--that's another topic.

1:06:14.409 --> 1:06:20.509
Humans do not advertise their
estrus.

1:06:20.510 --> 1:06:23.060
Not only do we not--remember
the chimps advertise their

1:06:23.056 --> 1:06:25.836
estrus in order to get the males
together and have the males

1:06:25.838 --> 1:06:26.828
compete for them.

1:06:26.829 --> 1:06:30.719
Humans keep it secret;
not only don't the males know

1:06:30.724 --> 1:06:35.294
when a female is in estrus,
but the female herself does not

1:06:35.286 --> 1:06:38.796
when she is estrus,
and for a very long time it was

1:06:38.797 --> 1:06:42.077
believed that females are
fertile during their periods.

1:06:42.079 --> 1:06:45.699
It was only in the 1930s that
it was found out by a Japanese

1:06:45.704 --> 1:06:49.454
group that females are fertile
in the mid-period between their

1:06:49.451 --> 1:06:51.521
periods,
and even further,

1:06:51.521 --> 1:06:55.861
it was believed in the 1930s
that females are fertile a few

1:06:55.860 --> 1:07:00.500
days before and a few days after
the middle of ovulation in the

1:07:00.498 --> 1:07:03.278
middle of the period,
and in fact,

1:07:03.277 --> 1:07:06.817
we now know just from about ten
years ago that the actual

1:07:06.820 --> 1:07:10.110
fertile period always is only
precedes ovulation.

1:07:10.110 --> 1:07:12.620
Then intercourse must take
place before ovulation.

1:07:12.619 --> 1:07:16.119
Not only do we--do human
females not advertise to the

1:07:16.119 --> 1:07:17.759
females,
they don't know,

1:07:17.760 --> 1:07:20.350
and scientists,
with all our investigations,

1:07:20.349 --> 1:07:22.309
have just now finally figured
out, we think,

1:07:22.309 --> 1:07:25.639
when a human female is fertile.

1:07:25.639 --> 1:07:27.249
This is a big,
big change.

1:07:27.253 --> 1:07:32.503
It's such a big part;
the advertising is such a big

1:07:32.500 --> 1:07:39.110
part of primate sexuality,
why has it disappeared in

1:07:39.112 --> 1:07:40.412
humans?

1:07:40.409 --> 1:07:45.599
It may be sort of the reverse,
that if females are out there

1:07:45.596 --> 1:07:49.876
alone and there's carnivores,
you read about this from the

1:07:49.880 --> 1:07:52.980
Ache, that there are lions and
tigers out there ready to eat

1:07:52.976 --> 1:07:55.106
them,
and they need protection of

1:07:55.106 --> 1:07:57.986
various sorts and maybe help in
finding food,

1:07:57.989 --> 1:08:01.129
so it's important to have a
male hanging around.

1:08:01.130 --> 1:08:05.080
A male's evolutionary purpose
is he wants to inseminate the

1:08:05.079 --> 1:08:07.809
female,
so if he knows when a female's

1:08:07.813 --> 1:08:10.673
having estrus,
he has to be there then to

1:08:10.668 --> 1:08:11.748
inseminate her.

1:08:11.750 --> 1:08:16.140
If he knows when she is in
estrus he also knows when she is

1:08:16.141 --> 1:08:19.761
not in estrus,
and when she's not in estrus he

1:08:19.762 --> 1:08:24.582
may have no evolutionary push to
stay there but go out and try to

1:08:24.582 --> 1:08:26.542
find some other female.

1:08:26.538 --> 1:08:30.378
The purpose of not showing your
estrus may be to keep the male

1:08:30.375 --> 1:08:33.895
uncertain of when you are
fertile and therefore he has to

1:08:33.896 --> 1:08:36.346
attend to the female all the
time,

1:08:36.350 --> 1:08:41.130
and once he's there he might as
well help her because that will

1:08:41.131 --> 1:08:45.761
insure that whatever infants
come along are in good shape.

1:08:45.760 --> 1:08:49.840
If that's correct,
and certainly males and females

1:08:49.841 --> 1:08:54.171
started spending more time
together, and they're more

1:08:54.172 --> 1:08:57.422
dispersed;
that reduces male/male

1:08:57.420 --> 1:08:58.650
competition.

1:08:58.649 --> 1:09:01.339
Remember the male/male
competition is a result of a

1:09:01.337 --> 1:09:03.807
group in which a lot of males
stay together.

1:09:03.810 --> 1:09:08.870
When you're more dispersed,
male/male competition has to be

1:09:08.867 --> 1:09:09.737
reduced.

1:09:09.738 --> 1:09:14.458
It looks like in the evolution
to humans that's--

1:09:14.460 --> 1:09:18.210
what's switching is from the
advertising which allows the

1:09:18.212 --> 1:09:22.572
males to compete and the female
gets the male with best genes,

1:09:22.569 --> 1:09:26.149
she's switching to wanting
resources from the male.

1:09:26.149 --> 1:09:29.609
She's no longer interested so
much in male competition but in

1:09:29.606 --> 1:09:33.056
whatever resources the male can
bring to her by having a male

1:09:33.064 --> 1:09:34.394
around continually.

1:09:34.390 --> 1:09:36.920
This story is rather
complicated and very

1:09:36.917 --> 1:09:40.897
controversial and there's a very
nice reading in your packet.

1:09:40.899 --> 1:09:45.529
It might be interesting to
consider that,

1:09:45.530 --> 1:09:51.900
how does the male respond to
this change in strategy?

1:09:51.899 --> 1:09:56.709
If the road to monogamy starts
going down then paternity

1:09:56.707 --> 1:09:58.717
becomes more certain.

1:09:58.720 --> 1:10:01.980
In the chimps,
where the female is copulating

1:10:01.983 --> 1:10:05.323
with everyone,
there's no reason to be certain

1:10:05.319 --> 1:10:07.099
of paternity at all.

1:10:07.100 --> 1:10:11.050
Once it becomes clear that,
yes, this child is almost

1:10:11.051 --> 1:10:14.331
certainly mine,
then it becomes evolutionary

1:10:14.331 --> 1:10:18.151
advantageous for the male to
start putting resources into

1:10:18.154 --> 1:10:22.254
this mother and child because
that insures their survival and

1:10:22.252 --> 1:10:25.942
things start developing in a
different direction.

1:10:25.939 --> 1:10:29.589
Where stable pairing becomes an
evolutionarily advantage,

1:10:29.591 --> 1:10:33.511
the male putting resources into
the pair are for evolutionary

1:10:33.506 --> 1:10:34.416
advantage.

1:10:34.420 --> 1:10:38.230
It seems pretty clear that an
increase in the male

1:10:38.234 --> 1:10:43.224
contribution to child rearing is
one of the major reasons for the

1:10:43.215 --> 1:10:48.325
increased fertility of humans--
why humans are able to out

1:10:48.327 --> 1:10:50.437
reproduce chimpanzees.

1:10:50.439 --> 1:10:55.409
Of course, as you all are
aware, monogamy has not by any

1:10:55.412 --> 1:11:00.662
means taken human societies
totally over and some societies

1:11:00.657 --> 1:11:04.847
overtly sanction polygamy,
but even in our culture which

1:11:04.846 --> 1:11:08.266
Europe and North America--
genetic testing shows that 10%

1:11:08.274 --> 1:11:12.764
to 15% of humans do not have the
father that they're supposed to

1:11:12.760 --> 1:11:13.330
have.

1:11:13.328 --> 1:11:15.758
'Father' is usually defined as
the resident male;

1:11:15.760 --> 1:11:19.370
he's not the father,
and that's quite a large

1:11:19.372 --> 1:11:20.442
percentage.

1:11:20.439 --> 1:11:25.279
American women report 6
different sexual partners

1:11:25.275 --> 1:11:29.705
lifetime and males report 16
female partners,

1:11:29.710 --> 1:11:31.020
lifetime.

1:11:31.020 --> 1:11:34.320
Now one thing we know if you're
at all mathematical that the--

1:11:34.319 --> 1:11:38.829
since it takes two to tango,
the average has to be the same

1:11:38.831 --> 1:11:42.951
so it can't be both 6 and 16,
and who knows possibly

1:11:42.945 --> 1:11:46.715
somewhere in between is correct,
but probably higher because

1:11:46.721 --> 1:11:48.641
these things tend to be under
reported,

1:11:48.640 --> 1:11:51.580
no one wants to really
say--well females certainly

1:11:51.582 --> 1:11:54.772
don't want to say how
promiscuous they are usually and

1:11:54.768 --> 1:11:56.268
also that's old data.

1:11:56.270 --> 1:12:00.900
This is from 2001 and with the
change of sexual mores in the

1:12:00.899 --> 1:12:04.189
Western countries,
I'm sure the numbers are

1:12:04.194 --> 1:12:06.474
exponentially increasing.

1:12:06.470 --> 1:12:12.070


1:12:12.069 --> 1:12:16.049
What's--another thing about
this thing with respect to human

1:12:16.048 --> 1:12:19.758
evolution is that when you're a
chimpanzee the male--

1:12:19.760 --> 1:12:22.000
the main form of competition is
male/male fighting,

1:12:22.000 --> 1:12:24.380
male/male status jockeying
which takes a certain amount of

1:12:24.375 --> 1:12:26.495
intelligence to arrange
coalitions and so forth,

1:12:26.500 --> 1:12:29.220
but basically evolution is
pushing you to be big and

1:12:29.216 --> 1:12:29.746
violent.

1:12:29.750 --> 1:12:33.780
Now the individuals disperse,
the male stays with the female,

1:12:33.780 --> 1:12:36.940
the males starts bringing
resources, violence is

1:12:36.939 --> 1:12:37.879
decreased.

1:12:37.880 --> 1:12:41.930
The importance of that in the
male evolution decreases and the

1:12:41.926 --> 1:12:45.306
importance of being able to
provide resources become

1:12:45.309 --> 1:12:48.959
evolutionarily important,
so the kind of intelligence

1:12:48.956 --> 1:12:51.896
required to find food in a
scarce environment,

1:12:51.899 --> 1:12:54.589
to find shelter,
to protect from animals and so

1:12:54.588 --> 1:12:56.108
forth becomes important.

1:12:56.109 --> 1:13:01.719
A fair reason for the increase
in human mental capacity might

1:13:01.716 --> 1:13:06.476
also be this shift from a
dependence on violence for

1:13:06.484 --> 1:13:11.904
competition to a dependence on
acquisition of resources for

1:13:11.904 --> 1:13:15.274
competition and for evolution.

1:13:15.270 --> 1:13:19.540
I've run out time and so we
will continue with humans and

1:13:19.542 --> 1:13:23.132
how they are different from
chimps next time.

1:13:23.130 --> 1:13:28.000