Dave Hone

So one of them is sex, but one of them is social.

It can, but then you get things like the other one I go for is black swans, these beautiful Australian birds.

They have these really weird curly feathers on their wings.

And males and females both have them.

And males prefer females with curlier feathers and females prefer males with curlier feathers.

There's an obvious sexual link.

But then females fight too.

Females fight over the best nesting spots.

And the females with the curliest feathers tend to win those fights.

How does that make sense?

This gets into classic sexual selection theory.

It's what's called an honest signal.

You couldn't have those curly feathers if you weren't able to support them.

Oh, yeah.

Because they're their primary feathers on the wings.

And what it actually does is it makes it harder to fly.

So you're basically going, look how tough I am.

I've grown this big and I can fly and carry on with my giant curly feathers.

because I'm really tough and I'm in good shape.

And it's the same with the lion.