The findings suggest that what a female pays attention to when she sizes up a potential mate isn’t what some researchers had thought.

All those dramatic eyespots? Meh. But the width of his feather train? She’s definitely checking that out. And when he turns around and shakes his tail feathers? That’s totally hot.

The peacock’s tail gave Darwin fits. At first, it seemed to fly in the face of his theory of natural selection. How could evolution possibly favor such cumbersome and conspicuous accoutrement? The very sight of those feathers, Darwin famously wrote to a colleague, made him sick. He soon realized, however, that the feathers might serve another purpose: enhancing the male’s reproductive success even as they made him more visible and vulnerable to predators. The concept of sexual selection was born, and the peacock’s tail remains a textbook example of it to this day.

But exactly what it is about the male’s display that females find attractive is far less clear.