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TED2013

Christopher Ryan: Are we designed to be sexual omnivores?

February 28, 2013

An idea permeates our modern view of relationships: that men and women have always paired off in sexually exclusive relationships. But before the dawn of agriculture, humans may actually have been quite promiscuous. Author Christopher Ryan walks us through the controversial evidence that human beings are sexual omnivores by nature, in hopes that a more nuanced understanding may put an end to discrimination, shame and the kind of unrealistic expectations that kill relationships.

Christopher Ryan - Psychologist
The co-author of "Sex at Dawn," Christopher Ryan explores the prehistoric roots of human sexuality. Full bio

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Double-click the English subtitles below to play the video.
I'm going to go off script
00:12
and make Chris quite nervous here
00:13
by making this audience participation.
00:15
All right. Are you with me? Yeah. Yeah. All right.
00:17
So what I'd like to do is have you raise your hand
00:21
if you've ever heard a
heterosexual couple having sex.
00:23
Could be the neighbors, hotel room,
00:27
your parents. Sorry.
00:30
Okay. Pretty much everybody.
00:32
Now raise your hand if the man was making
00:33
more noise than the woman.
00:35
I see one guy there.
00:39
It doesn't count if it was you, sir.
00:41
(Laughter)
00:43
So his hand's down. And one woman. Okay.
00:44
Sitting next to a loud guy.
00:48
Now what does this tell us?
00:50
It tells us that human beings
00:51
make noise when they have sex,
00:53
and it's generally the woman who makes more noise.
00:55
This is known as female copulatory vocalization
00:57
to the clipboard crowd.
01:00
I wasn't even going to mention this,
01:01
but somebody told me that Meg Ryan might be here,
01:03
and she is the world's most famous
01:06
female copulatory vocalizer.
01:08
So I thought, got to talk about that.
01:10
We'll get back to that a little bit later.
01:13
Let me start by saying human beings
01:16
are not descended from apes,
01:17
despite what you may have heard. We are apes.
01:20
We are more closely related
to the chimp and the bonobo
01:22
than the African elephant is to the Indian elephant,
01:25
as Jared Diamond pointed
out in one of his early books.
01:28
We're more closely related to chimps and bonobos
01:31
than chimps and bonobos are related
01:35
to any other primate --
01:37
gorillas, orangutans, what have you.
01:39
So we're extremely closely related to them,
01:41
and as you'll see in terms of our behavior,
01:44
we've got some relationship as well.
01:47
So what I'm asking today, the question
01:49
I want to explore with you today is,
01:51
what kind of ape are we in terms of our sexuality?
01:54
Now, since Darwin's day there's been
01:58
what Cacilda and I have called
02:00
the standard narrative of human sexual evolution,
02:02
and you're all familiar with it,
02:04
even if you haven't read this stuff.
02:06
The idea is that, as part of human nature,
02:09
from the beginning of our species' time,
02:12
men have sort of leased
women's reproductive potential
02:14
by providing them with certain goods and services.
02:18
Generally we're talking about meat, shelter, status,
02:22
protection, things like that.
02:25
And in exchange, women have offered fidelity,
02:28
or at least a promise of fidelity.
02:30
Now this sets men and women up
in an oppositional relationship.
02:33
The war between the sexes is built right into
our DNA, according to this vision. Right?
02:37
What Cacilda and I have argued is that no,
02:43
this economic relationship,
02:47
this oppositional relationship,
02:49
is actually an artifact of agriculture,
02:51
which only arose about 10,000
years ago at the earliest.
02:54
Anatomically modern human beings
02:57
have been around for about 200,000 years,
02:59
so we're talking about five percent, at most,
03:02
of our time as a modern, distinct species.
03:06
So before agriculture,
03:10
before the agricultural revolution,
03:13
it's important to understand that human beings
03:15
lived in hunter-gatherer groups that are
03:17
characterized wherever they're found in the world
03:21
by what anthropologists called fierce egalitarianism.
03:24
They not only share things,
03:28
they demand that things be shared:
03:30
meat, shelter, protection, all these things
03:33
that were supposedly being traded to women
03:35
for their sexual fidelity, it turns out,
03:38
are shared widely among these societies.
03:41
Now I'm not saying that our ancestors
03:44
were noble savages, and I'm not saying
03:46
modern day hunter-gatherers
are noble savages either.
03:48
What I'm saying is that this is simply
03:50
the best way to mitigate risk
03:52
in a foraging context.
03:55
And there's really no argument
about this among anthropologists.
03:57
All Cacilda and I have done is extend
this sharing behavior to sexuality.
04:00
So we've argued that human sexuality
04:05
has essentially evolved, until agriculture,
04:07
as a way of establishing and maintaining
04:11
the complex, flexible social systems, networks,
04:15
that our ancestors were very good at,
04:18
and that's why our species has survived so well.
04:21
Now, this makes some people uncomfortable,
04:26
and so I always need to take
a moment in these talks
04:28
to say, listen,
04:30
I'm saying our ancestors were promiscuous,
04:32
but I'm not saying they were
having sex with strangers.
04:35
There were no strangers. Right?
04:37
In a hunter-gatherer band, there are no strangers.
04:39
You've known these people your entire life.
04:41
So I'm saying, yes, there were
overlapping sexual relationships,
04:43
that our ancestors probably had
several different sexual relationships
04:47
going on at any given moment in their adult lives.
04:51
But I'm not saying they were
having sex with strangers.
04:54
I'm not saying that they didn't love the
people they were having sex with.
04:57
And I'm not saying there was
no pair-bonding going on.
05:00
I'm just saying it wasn't sexually exclusive.
05:03
And those of us who have
chosen to be monogamous --
05:06
my parents, for example, have been married
05:09
for 52 years monogamously,
05:12
and if it wasn't monogamously, Mom and Dad,
05:14
I don't want to hear about it—
05:17
I'm not criticizing this and I'm not saying
05:19
there's anything wrong with this.
05:21
What I'm saying is that to argue
05:23
that our ancestors were sexual omnivores
05:25
is no more a criticism of monogamy
05:30
than to argue that our ancestors
were dietary omnivores
05:32
is a criticism of vegetarianism.
05:36
You can choose to be a vegetarian,
05:39
but don't think that just because
you've made that decision,
05:41
bacon suddenly stops smelling good.
05:44
Okay? So this is my point.
05:46
(Laughter)
05:49
That one took a minute to sink in, huh?
05:51
Now, in addition to being a great genius,
05:55
a wonderful man, a wonderful husband,
05:57
a wonderful father, Charles Darwin
05:59
was also a world-class Victorian prude.
06:01
All right? He was perplexed
06:05
by the sexual swellings of certain primates,
06:07
including chimps and bonobos,
06:10
because these sexual swellings tend to provoke
06:11
many males to mate with the females.
06:14
So he couldn't understand why on Earth would
the female have developed this thing
06:16
if all they were supposed to be doing
is forming their pair bond, right?
06:20
Chimps and bonobos, Darwin didn't really know this,
06:24
but chimps and bonobos mate
06:26
one to four times per hour
06:28
with up to a dozen males per day
06:30
when they have their sexual swellings.
06:33
Interestingly, chimps have sexual swellings
06:36
through 40 percent, roughly,
06:38
of their menstrual cycle,
06:40
bonobos 90 percent,
06:42
and humans are among the
only species on the planet
06:45
where the female is available for sex
06:48
throughout the menstrual cycle,
06:50
whether she's menstruating,
whether she's post-menopausal,
06:52
whether she's already pregnant.
06:55
This is vanishingly rare among mammals.
06:56
So it's a very interesting aspect of human sexuality.
07:00
Now, Darwin ignored the reflections
07:04
of the sexual swelling in his own day,
07:07
as scientists tend to do sometimes.
07:10
So what we're talking about is sperm competition.
07:14
Now the average human ejaculate
has about 300 million sperm cells,
07:16
so it's already a competitive environment.
07:20
The question is whether these sperm are
competing against other men's sperm
07:22
or just their own.
07:25
There's a lot to talk about in this chart.
07:27
The one thing I'll call your attention to right away
07:29
is the little musical note above the
female chimp and bonobo and human.
07:31
That indicates female copulatory vocalization.
07:35
Just look at the numbers.
07:39
The average human has sex
07:40
about 1,000 times per birth.
07:43
If that number seems high for some of you,
07:46
I assure you it seems low for others in the room.
07:48
We share that ratio with chimps and bonobos.
07:52
We don't share it with the other three apes,
07:55
the gorilla, the orangutan and the gibbon,
07:57
who are more typical of mammals,
07:59
having sex only about a dozen times per birth.
08:01
Humans and bonobos are the only
animals that have sex face-to-face
08:04
when both of them are alive.
08:08
(Laughter)
08:11
And you'll see that the human, chimp and bonobo
08:15
all have external testicles, which in our book
08:18
we equate to a special fridge you have in the garage
08:21
just for beer.
08:25
If you're the kind of guy who has a beer fridge
08:27
in the garage, you expect a party to happen
08:30
at any moment, and you need to be ready.
08:32
That's what the external testicles are.
08:34
They keep the sperm cells cool
08:36
so you can have frequent ejaculations.
08:38
I'm sorry. It's true.
08:41
The human, some of you will be happy to hear,
08:44
has the largest, thickest penis of any primate.
08:47
Now, this evidence goes way beyond anatomy.
08:50
It goes into anthropology as well.
08:53
Historical records are full of accounts of people
08:55
around the world who have sexual practices
08:58
that should be impossible
09:00
given what we have assumed
about human sexual evolution.
09:01
These women are the Mosuo
from southwestern China.
09:05
In their society, everyone, men and women,
09:08
are completely sexually autonomous.
09:11
There's no shame associated with sexual behavior.
09:12
Women have hundreds of partners.
09:15
It doesn't matter. Nobody cares.
Nobody gossips. It's not an issue.
09:18
When the woman becomes pregnant,
09:21
the child is cared for by her,
her sisters, and her brothers.
09:23
The biological father is a nonissue.
09:25
On the other side of the planet, in the Amazon,
09:28
we've got many tribes which practice
09:31
what anthropologists call partible paternity.
09:34
These people actually believe --
09:36
and they have no contact among them,
09:39
no common language or anything,
09:41
so it's not an idea that spread,
09:42
it's an idea that's arisen around the world --
09:44
they believe that a fetus is literally made
09:46
of accumulated semen.
09:48
So a woman who wants to have a child
09:51
who's smart and funny and strong
09:53
makes sure she has lots of sex with the smart guy,
09:54
the funny guy and the strong guy,
09:56
to get the essence of each of
these men into the baby,
09:58
and then when the child is born,
10:01
these different men will come forward
10:03
and acknowledge their paternity of the child.
10:05
So paternity is actually sort of a team endeavor
10:08
in this society.
10:11
So there are all sorts of examples like this
10:13
that we go through in the book.
10:15
Now, why does this matter?
10:17
Edward Wilson says we need to understand
10:21
that human sexuality is first a bonding device
10:23
and only secondarily procreation.
10:26
I think that's true. This matters because
10:29
our evolved sexuality is in direct conflict
10:31
with many aspects of the modern world.
10:34
The contradictions between what we're told
10:37
we should feel and what we actually do feel
10:39
generates a huge amount of unnecessary suffering.
10:42
My hope is that a more accurate,
10:47
updated understanding of human sexuality
10:50
will lead us to have greater tolerance for ourselves,
10:52
for each other,
10:55
greater respect for unconventional
relationship configurations
10:57
like same-sex marriage or polyamorous unions,
11:01
and that we'll finally put to rest the idea
11:06
that men have some innate, instinctive right
11:09
to monitor and control women's sexual behavior.
11:12
(Applause)
11:16
Thank you.
11:19
And we'll see that it's not only gay people
11:21
that have to come out of the closet.
11:23
We all have closets we have to come out of. Right?
11:25
And when we do come out of those closets,
11:29
we'll recognize that our fight is not with each other,
11:30
our fight is with an outdated,
Victorian sense of human sexuality
11:34
that conflates desire with property rights,
11:38
generates shame and confusion
11:42
in place of understanding and empathy.
11:45
It's time we moved beyond Mars and Venus,
11:48
because the truth is
11:50
that men are from Africa
11:52
and women are from Africa.
11:53
Thank you.
11:55
(Applause)
11:57
Chris Anderson: Thank you.
Christopher Ryan: Thank you.
12:06
CA: So a question.
12:08
It's so perplexing, trying to use arguments
12:10
about evolutionary history
12:14
to turn that into what we ought to do today.
12:17
Someone could give a talk and say,
12:20
look at us, we've got these really sharp teeth
12:22
and muscles and a brain that's really good
12:25
at throwing weapons,
12:27
and if you look at lots of societies around the world,
12:28
you'll see very high rates of violence.
12:31
Nonviolence is a choice like vegetarianism,
12:33
but it's not who you are.
12:37
How is that different
12:39
from the talk you gave?
12:41
CR: Well first of all, the evidence
12:44
for high levels of violence in prehistory
12:47
is very debatable.
12:50
But that's just an example.
12:53
Certainly, you know, lots of people say to me,
12:55
just because we lived a certain way in the past
12:59
doesn't mean we should live that
way now, and I agree with that.
13:01
Everyone has to respond to the modern world.
13:04
But the body does have its inherent
13:07
evolved trajectories.
13:11
And so you could live on
McDonald's and milkshakes,
13:14
but your body will rebel against
that. We have appetites.
13:18
I think it was Schopenhauer who said,
13:21
a person can do what they want
13:23
but not want what they want.
13:26
And so what I'm arguing against
13:28
is the shame that's associated with desires.
13:29
It's the idea that if you love your husband or wife
13:32
but you still are attracted to other people,
13:35
there's something wrong with you,
13:37
there's something wrong with your marriage,
13:39
something wrong with your partner.
13:41
I think a lot of families are fractured
13:42
by unrealistic expectations
13:44
that are based upon this false
vision of human sexuality.
13:46
That's what I'm trying to get at.
13:49
CA: Thank you. Communicated
powerfully. Thanks a lot.
13:51
CR: Thank you, Chris.
(Applause)
13:53

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Christopher Ryan - Psychologist
The co-author of "Sex at Dawn," Christopher Ryan explores the prehistoric roots of human sexuality.

Why you should listen

In the fascinating book Sex at Dawn, Christopher Ryan and co-author Cacilda Jethá, MD, explore how humans' prehistoric promiscuity (perhaps similar to the bonobos') may have influenced our current attitudes toward pair-bonding, monogamy and long-lasting passion. Their thesis draws on evidence from anthropology, archeology, primatology, anatomy and psychosexuality.

As a psychologist, Ryan’s research focuses on trying to distinguish the human from the cultural. His book, he hopes, is "pointing toward a more optimistic future illuminated by our innate capacities for love, cooperation and generosity."

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