"If the route between the two major North American ice sheets didn’t fully open until about 13,000 years ago, how did early Homo sapiens travel from Alaska down into the Americas and even to the tip ...

The setup is simple. One partner points out a bird to the other — or in a common variation, recounts a fake bird encounter from earlier in the day — and awaits a response. A partner who responds with ...

Chimpanzees use a variation of the "scientific method" — discarding prior beliefs if convincing new evidence comes along to change their minds, research shows.