Ancient footprints discovered in Kenya belong to two different species of human relatives who walked on the same ground at the same time, a study found. The prints are thought to belong to the species ...

Researchers have uncovered an unusual survival strategy in Iberian harvester ants that turns basic biology on its head: The queens can produce eggs that develop into two different ant species. A team ...

There are no wild ligers. Indeed, hybrids were once thought to be rare in nature—and of little consequence in an evolutionary sense. But now we know they can play an important role in speciation—the ...

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their ...