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)