Transcriber: Translate TED Reviewer: Denise R Quivu
Thank you very much!
I'm Joan Roughgarden and I'm a biologist,
and I'm here to talk about the evolution of gender and sexuality.
And, the reason I'm doing this is that I attended my first Gay Pride Parade
in San Francisco about 12 years ago,
and when I was there I noticed this huge number of people
all of whom, biology said were somehow defective.
I thought that maybe it's not the people that are defective,
but is biology that's defective.
And, that began an investigation
into the extent of variation in gender and sexuality
which appeared in Evolution's Rainbow the first of the two books
that are on the screen here.
Now, the issue from a biologist point of view
with the diversity in gender and sexuality
is that it leads to challenges in what we teach in our ordinary curriculum.
And, this is a very unpleasant development,
so the existence of gender and sexuality variation is problematic
for biology and as you know,
it's also problematic in the political sector
and the religious sector as well.
Now, for biology specifically,
the problem concerns an area of evolution
called Darwin's Sexual Selection Theory.
And I'll tell you what that's about
and then show you that it's pretty obviously incorrect.
The first proposition that Darwin utters is that
"Males of almost all animals have stronger passions than females"
so, we have the phrase 'passionate male' tracing back to Darwin.
And, furthermore, he says that the female,
with the rarest of exceptions,
is less eager than the male, she is coy.
So we have the phrase 'coy female'.
And, in today's jargon 'passionate male' is replaced with 'promiscuous male'
and 'coy female' with 'constrained female'.
And the third premise from Darwin is the most problematic.
It pertains to characters
like the peacock's tail and the antler on a deer,
and it is that females...
And so Darwin was asking
why does the peacock have the tail and does the deer have the antler?
And his answer is that females choose mates
who are more attractive, vigorous and well-armed,
just as men can give beauty to his male [unclear].
So, he's invisioning that females are breeding males
to have the traits that they have.
Now, why, you might ask,
would females be chosing males with ornaments?
The idea is that the females have expensive eggs.
And the males, on the other hand, have cheap sperm
and so males are capable in principle of ranging far and wide
inseminating anything they come accross.
And females are necessarily obligated
to defend their expensive investment in eggs.
Therefore, the female is forced to be coy and choosy,
and the male passionate or promiscuous.
And this is the party line
that's currently taught in biology curricula worldwide.
It's a nice story, in a sense, at least it's a story.
But the question is whether it's true.
And let me show you some examples of diversity in gender and sexuality
that make these propositions almost useless.
And one thing I need to emphasize is that the two intial premises
the passionate male and the coy female,
are asserted as empirical generalizations.
So, if you go outside and you pick up a random bird or a random butterfly,
or any organism at random,
the male is supposed to be passionate and the female coy,
with very, very rare exceptions.
And it will be obvious that the exceptions are far from rare.
The first issue is that the assignement
into a sex, as male or female, is neither stable nor exclusive.
If you go diving on a coral reef,
about a third of the species that you see there
consist of individuals who are both sexes at the same time.
Or at different times during their life.
So, in the case of these species right here,
the individuals change from female to male, that is a kind of wrasse.
In the case of this species right here
they change from a male to female.
And as I say, 30% of the species,
if you simply go snorkeling on a coral reef,
you see this all around you.
And it's just simply not true
that the categories of males and females are stable or comprehensive.
Now, another important issue is called 'Sex-Role Reversal' by biologists.
And this pertains to males who do all the parental care
and females who have to hustle around
and find a male who is interested in them.
And the popular examples of this are the seahorses.
Now, in fish, the parental care is usually provided by the male.
And in birds, it's about 50/50 male and female
and in mammals is usually initially by the female.
But in fish, the style of parental care varies from species
and in many cases the males will glue the eggs to their tummy.
And that is true of... darn!
That's true of this species in the middle here which is a pipefish.
Now, the seahorses are related to pipefish
in that they have a big skin-flap on their tummy
and the females deposit eggs into the males' tummy.
So the males become, in a sense, pregnant.
So, this is a male seahorse receiving eggs from that female.
And what happens in this situation
is that you can get more females hanging around
looking for males to receive their eggs,
and in that situation then the males are in the position to decide
what female they want to allow to deposit eggs in their skin-flap.
So this is the exactly the reverse of the Darwinian story
that it's females who are choosing males,
here it's males who are choosing females.
Now, that shows that the size of the sperm or the egg can't be important
or definitive in determining the sex-role of the animal.
Because male seahorses make tiny sperm
but yet they are nonetheless the ones who wind up doing all the parental care.
In many species there are several genders of males.
In this species called the ruff
the one on the left is a male with a black collar around it
the one at the top has a white collar,
and the one on the far right has no collar.
Now, the black colored males, at the time of mating,
go into an area which is called a 'lek'
which is basically a red light district of males.
And, when the females are foraging by themselves
and they want some sex,
they just go and fly over to the lek
where all the black colored males are hanging out
and then the males try to attract them into mating with them.
But the plot thickens,
because this white colored male at the top,
hangs out with the females for a little while and gets to know them,
and then he leaves those females before they approach the lek
and he goes to the lek where the black colored males are,
the black colored males court him and ask him to join them.
So, when the females arrive
they find some territories with two colors, two styles of males,
and the females prefer to mate with the pair of males of the two colors
rather than with the males with one color by itself.
And, I conjecture that the reason for that is that the white colored mates
get to know the females
and can serve, so to speak, as marriage brokers,
when the females fly into the black colored males
they can make introductions and invite specific females to join them.
In any case,
the existence of multiple types of males also contradicts the Darwinian story
in which all males are of one type and all females another.
Then, we get to the question of homosexuality.
There's a lot of mating that takes place between animals of the same sex.
And these are elephants right here.
These are big horn sheep from Montana.
And these are primates, our closest relatives.
And there's well over 300 species of vertebrates alone
in which same sex sexuality has been observed in nature.
So, this is quite common.
And officially observed and published in the primary literature.
Now, these are gorillas on the left, which is a male-male interaction
and now in the center and right
we have a female-female interaction between bonobos.
And female bonobos, well,
mate with one another several times during the day,
as a form of networking.
So, what's really going on here
is that there's a lot of physical intimacy between animals,
not only same sex sexuality, but also multiple grooming,
reciprocal grooming, reciprocal preening.
And all of these forms of behavior are ways of exchanging physical pleasure
with one another.
And I've suggested that the reason
this evolves is as a mechanism to produce bounding
and collaboration between individuals.
And when individuals are physically intimate with one another
they're able to coordinate their activities
and work toward a common goal
because they experience mutual pleasure in achieving a common goal.
So, it's actually the realization of the common goal
that is pleasurable in these intimate interactions.
Now, in light of all of this
the whole idea of sexual selection looks almost absurd.
It's incorrect, but it also is irrelevant,
it doesn't even address the degree of diversity that occurs in nature.
The issue of collaboration brings us to the next issue
which is the one of family.
And biologists, I believe, also have an incorrect account of family life.
This is a quotation from Jeff Parker in the U.K.
"The family is now perceived as a cauldron of conflict,
with each of the players having different interests...
sexual conflict, parent-offspring conflict,
and sib-conflict simultaneously."
And this too is taught in the biology curricula.
And, if it were true, it paints a bleak picture of the aspirations
that we all share here of building a better life
and founded on collaboration, but it may not be true.
The idea of biological family
that I've been suggesting in the last year,
is summarized in this diagram,
in which the parent-parent relatioship is essentially colaborative
and the collaboration is realized through physical intimacy
that produces cooperation that resolves genetic conflict.
Because we can't avoid the fact
that there is genetic conflict at the beginning.
But it needs to get resolved.
Now, with respect to the parent-offspring relationship,
my suggestion is that there is an effect in auction of resources to offspring
that produce an incentive to resolve the genetic conflict.
And what I'm doing here is drawing on the economic theory
of the firm from economics.
And viewing a family as it was a firm or a company whose products is offsprings.
And asking whether or not the organization,
the economic organization of a firm,
could serve as a guide to understanding animal family life.
And the specifics are that in the parent-offspring firm,
the parent is in the position to give food to the offspring,
and what the parent does is indicates the price of the food to the offspring
and the offspring pay for this by the quantity
of begging that they carry out.
And the offspring are able to communicate their demand curve to the parent.
And if the parent knows the demand curve
it can set the price of food that it charges to the offspring,
so that the offspring honestly communicate their needs to the parent.
And when that happens the family functions as a very efficient unit
for the production of offspring.
And therefore we get the formation of collaboration in two ways.
Either through collaboration, either through physically intimacy
which produces a collaboration.
Or through the setting of incentives, and the circumstances differ.
So, I've been blessed in all my work by the help of these collaborators,
Erol Akçay, who's from Turkey, and Priya Iyer, who's from India.
So, thank you so much.
(Applause)