Did males get bigger or females smaller?

Don’t just say he’s bigger. When it comes to bird species with jumbo-size males, we may have to rethink evolutionary history and say that in some cases the female’s smaller, according to Chicago researchers.

Biologists have long assumed that these male-female size differences arose from pressures on males to bulk up for macho competitions or greater appeal to females, explains Jordan

Karubian of the University of Chicago.