WASHINGTON — A little strategically placed makeup quickly turns the wimpiest of male barn swallows into chick magnets, amping up their testosterone and even trimming their weight, new research shows.
It’s a “clothes make the man” lesson that — with some caveats — also applies to human males, researchers say.
Using a $5.99 marker, scientists darkened the rust-colored breast feathers of male New Jersey barn swallows, turning lighter birds to the level of those naturally darkest.
They had already found, in a test three years ago, that the marked-up males were more attractive to females and mated more often.
This time they found out that the more attractive appearance, at least in the bird world, triggered changes to the animals’ body chemistry, increasing testosterone.
“It’s the ‘clothes make the man’ ” idea, lead author Rebecca Safran said. “It’s like you walk down the street and you’re driving a Rolls-Royce and people notice. And your physiology accommodates this.”
The birds’ weight loss is more easily explained, Safran said: The more macho swallows could be spending more time mating than eating.
