You can engineer a prairie vole to become monogamous when it's naturally polygamous.

Females after their first calf is already weaned a lower load.

So the males will go out, they'll look for females, they'll mate. If they mate successfully, then no offspring.

Third Female

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

Those females, they're not trying to.

It's just the female.

The gourd is a feminine aspect the stick is a male.

Now, the mother then can go and reproduce, but what a terrible price to pay for the accumulation of this pollutant in these animals the death of the first born calf.

As Darwin did not believe that pure aesthetics would guide female peacocks and lions in their choice of mating partners, he had to find a rational reason for females preference for males with hindering characteristics. The very fact, he reasoned, that these features make life harder signals to prospective partners that individuals who can do reasonably well with them have an especially good genetic set up and are thus likely to produce strong offspring.

DG This is a female of this kind of worm.

And, interestingly, this has been observed in female macaques, but only when mounting another female.

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

And the second is a phenomenon that males are very, very good at finding females.

The tigress...

And she?

Specifically, it's male fireflies who are all flashing in perfect time together, in perfect synchrony, to reinforce a message to the females.

So when you develop a cancerous cell in your breast, aromatase converts androgens into estrogens, and that estrogen turns on or promotes the growth of that cancer so that it turns into a tumor and spreads.

To overcome her?

There are over eight words for what they call animal favoritism selective proceptivity, mate choice, female choice, sexual choice.

According to recent scientific reports, the number of nesting female Pacific leatherback sea turtles has declined by 95 percent since 1980 and is expected to go extinct within the next 5 30 years unless efforts are taken to reverse their decline.

Because it turns out that the number one cancer in women, breast cancer, is regulated by estrogen and by this enzyme aromatase.

The death rate in these dolphins, for the first calf born of every female dolphin, is 60 to 80 percent.

In recent studies that we've published, we've shown that some of these animals when they're exposed to atrazine, some of the males grow up and completely become females.

She'll holler on me.

There's a hind. There's a doe.

Down below here, we see calls made by both males and females that also carry over very long ranges.

It's only the female mosquito that will actually bite you.

(a) The principle of joint responsibility means that parents must raise their children and the State must help them to perform that duty.

Gracia is a cute female toucan, exuding the breath of tropical rain forest.

We've separated the males from the females.

There's only 8,000 basking shark females in the world?

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

And these two males are fighting, they do it by bouncing their butts together, which is an interesting concept. Now, here's a male on the left and a female on the right, and the male has managed to split his coloration so the female only always sees the kinder gentler squid in him.

Meet the hermaphrodites.

It's interesting, because it was six years ago when I was pregnant with my first child that I discovered that the most commonly used preservative in baby care products mimics estrogen when it gets into the human body.

3.2 Parental responsibility

And she says, What? Only the females have eggs?

She submits to the stronger.

But what atrazine does is it turns on an enzyme, the machinery if you will, aromatase, that converts testosterone into estrogen.

They all live in colonies consisting of one or a few queens, and then all the ants you see walking around are sterile female workers.

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.

And this is not just philosophical, it's already known, that chemicals like diethylstilbestrol and estrogen, PCBs, DDT cross the placenta and effectively determine the likelihood of developing breast cancer and obesity and diabetes already when the baby's in the womb.

He's coming up to one of my graduate students and flipper patting, which he would do to a female penguin.

So if we can tell the gender of the shark before we sample it, we can tell the geneticist this was taken from a male or a female.