By the way, with aphids you have only females, like Amazons.

For those desert lizards, the answer is easy. It's a girl.

Metz

I killed him. But I didn't know it then and I'm not going to die for it.

They do it by bouncing their butts together, which is an interesting concept.

Kristen, put the scalpel down.

Juveniles a huge load.

I already threw her half my lunch. How do you know it's a she?

Is that dog male or female?

Those females, they're not trying to.

So here's a typical situation, male meets female, lots of offspring.

And there she goes!

Students are not taught to work in groups.

Now, it turns out we only kill the female mosquitoes.

You know what I mean. One female runs the whole show.

(Laughter)

Been up in a fat sheep, have ya?

She always knows where he is, and she doesn't have to be monogamous, because some of these females come up with multiple males attached.

Alberto worked with the bucardo in Spain.

(Laughter) That was the problem.

That was the problem.

They are a nearly all female species, and although they still lay eggs, these eggs hatch out female clones of themselves.

You know, in primates, there is this phenomenon called sexual dimorphism, which simply means males are larger than females and males have larger teeth than the females.

They were too young to survive without their mother.

It's always a girl.

There you are. We've sent mosquito eggs.

If there's a male mosquito that you release, and if there's a female around, that male will find the female.

However, in these animals, one Z and one W chromosome together, as a pair, produces a female.

So that was the goal of my design.

Well, this is a deep sea version of Women's Lib.

You see, clownfish all start out their lives as males,

(Laughter)

My favorite being, Cheese crumbs spread before a pair of copulating rats will distract the female, but not the male.

I would, except this is a female gorilla. Uhoh!

And medication didn't help him anymore.

They also spend their lives in small groups with a strict dominance hierarchy where only the most dominant male and female reproduce.

Take whiptail lizards, for example.

If a larva lands on the open sea floor, then it will become a female.

For others, it's answered by the environment.

We gave samples to Mary Schweitzer, and she was actually able to determine that B rex was a female based on medullary tissue found on the inside of the bone.

(Laughter)

One is more bitter than the other

For this species, it is simply a matter of where a larva happens to randomly fall on the sea floor.

They can live to be 60 years or more, although we think most of them probably don't make it to 60 in the wild.

So some people will bring up evolutionary biology and apes, how, you know, female apes bow down to male apes and that sort of thing.