The Surprising Power of Sex in Evolution

The Surprising Power of Sex in Evolution

Hey there, smart people.

Unless you're from another planet, you know that peacocks are famous for their spectacular, iridescent tail feathers. And you probably know what these flamboyant males use their beautiful behinds for: to impress the ladies. But what you may not know is that this bird, along with countless other gorgeous creatures, so confounded Charles Darwin that he had to develop an entirely different theory of evolution to explain it.

This letter is about another of Darwin's great ideas, ones that can explain some of nature's strangest behaviors and most beautiful forms. But it took a century for most scientists to accept this. And to tell this story, let's go straight to the source to understand the Peacock Paradox. Because when evolution meets "segs" or...sex, strange things happen. So why did the peacock so confound Darwin? Huh? Well, Chuck D. recanted the theory of natural selection in 1859, changing science forever. Animals and plants with traits that are better adapted to their environment survive and reproduce more often, and over time those traits become more common.

But this view alone does not explain everything. Many characteristics seem completely unsuited to an animal's environment. In fact, they may even be dangerous to survival. This is the paradox that puzzled Darwin: why would nature allow so many traits to evolve beyond those that were optimal for survival? Darwin recognized that some traits are not well adapted to the environment; they are better suited to one sex. We call this sexual selection. If a trait is useful, it will be sexually selected. Some individuals will reproduce more than others, and this can happen in two ways: First, males can compete directly with each other for mates.

Darwin called this the law of contestation, and if this was the only thing to consider in sexual selection, it would be very simple. But as you can see, there are still a few minutes left in this video, because the mere fact that males are competing with each other does not explain it. You can't fight against the male's magnificent plumage.

Another important type of sexual selection is mate choice, and in nature it is usually the female who chooses the male. It's hard to believe that a female would blindly choose a male. I'm sure she's looking for something. However, choosing a particular partner may have some direct benefits, such as: B. defending a territory or helping the male raise the young. But let's be honest, many fathers in nature contribute nothing but sperm and a bunch of genes. And this is true even for peacocks and peahens after mating. Mothers are pretty much working alone in the nest egg department.

So what's in it for these women? What is it? Well, beautiful or decorative features can be outward signs of health and good genes. But often, looking stylish isn't a reliable sign of actually being healthy and strong. We know that in peacocks, males must have one or more genes that allow them to grow ornaments. And different versions of these genes produce different tails.

For example, let's imagine that there is a gene for a flashy tail, and different versions produce different tail sizes. And assuming that, if females have something that programs them to prefer larger or more beautiful ornaments, their offspring will inherit the gene for larger ornaments from their father. And from their mothers, the gene for preferring larger ornaments will remain.

This means that larger and more flashy ornaments and the tendency to prefer larger and more flashy ornaments are associated, and over time both will become more common.

Sorry, ma'am, is there a genetic preference for a particular dick size? That's how picky females turn peacocks into the way they are. -- Yes, baby. --If peacocks were under the influence of normal natural selection, we might expect that males with small tails would be better at avoiding predators and would mate more frequently, and that peacocks' tail feathers would shrink over time. But in reality, females have a natural tendency to prefer larger tails, so males with small tails rarely mate. And sexual selection keeps roosters big and handsome, which is success. They can mate more often and pass on their genes to future generations, which makes up for the fact that their big, silly tails make them easy prey for predators. OK, so you're worried about predators? Is there anything you're worried about? This positive feedback loop, where you acquire a flashy trait and the opposite sex has a programmed preference for that trait, was first discovered by mathematician and biologist Ronald Fisher. Today, we call this type of sexual selection snowball effect the "Fisher Runaway Syndrome." This can also be applied to behavior.

For example, as bowerbird females evolved, they began to prefer males who were more ornamental. So which males had versions of genes that gave them more flashy ornaments? They mated more frequently than other species, and their ornaments became more elaborate over time. A later version of this idea became known as the sexy-son hypothesis. Other picky women prefer sexy sons, so women who choose physically attractive men tend to have more attractive sons and therefore produce more grandchildren. This is a bit odd, but evolutionarily speaking, the whole point of life is to pass on genes to the next generation. One way to achieve this is by using camouflage to perhaps survive longer. Or they could achieve this by mating more frequently through combat or fantasy. The elaborate plumage of the peacock shows us that females don't always select for traits that aid in the survival of their offspring. Guess how that happened? Do you think she liked it? Sometimes they select for traits that will help them breed better in their offspring.

In reality, natural and sexual selection usually occur simultaneously, but peacocks prove that sexual selection can be strong enough to outweigh normal state selection. Thus, the peacock paradox is not a paradox at all. The idea that females choose their mates was initially quite controversial, as it gives animal females a level of power and independence that human females did not really have at the time. In nature, males usually compete with other males for access to mates, leaving females more likely to make the choice. However, there are exceptions where these roles are reversed.

For example, female hyenas are larger and more dominant than males, and females compete with each other to mate. And when multiple queens hatch in a nest, the first one to emerge will kill any sister queens before they can do the same. And then there's this species of fly where the females are elaborately decorated and dance to lure males. And what about us? Well, these ideas of sexual selection can sometimes be applied to humans, but with a bit of caution. On the one hand, we are animals, animals for sure.

We are what we are thanks to natural selection and sexual selection. I mean dancing, flowers, and muscular men on the New Jersey shore. Darwin would be very happy about that. On the other hand, we also have the ability to make decisions based on culture and other preferences.

So I wouldn't say that everything people do on dates or in couples is attributable to evolution. Darwin’s confusion ultimately showed us that evolution runs on two engines: survival and reproduction.