This year, humanity landed on its first comet, a child was born to a woman with a transplanted womb, and a fossilized sea shell forced us to reconsider our conceptions of human culture. Those are just a taste of the 20 achievements, innovations, and advances we've selected for our roundup of 2014's biggest…
The ancestors of Native Americans came to the New World by walking over a land bridge across the Bering Strait. But there's a rather glaring 10,000 year gap in the story — one that could be explained by a migratory pause that lasted for millennia.
The land bridge that once connected North America and Asia rose from the seas 80,000 years ago. And at the same time, North America's climate began experiencing violent climate swings, with average temperatures shifting as much as ten degrees every decade.