When did human beings first set foot in the western hemisphere, and how did they arrive? For decades there has been a rough consensus among scientists studying the matter. The ancestors of the “Native Americans” were once immigrants themselves, and the first of them came across a landbridge from Siberia less than 16,000 years ago, as the glaciers of the last great Ice Age began to recede. Now, though, there is clear evidence that the consensus is wrong.
Footprints on the Sands of Time:
A study released last fall looked into the implications of footprints found in New Mexico in 2009, on material that must once have been mud and that soon thereafter hardened into rock.
The oldest of these footprints are 23,000 years old. That means humans were walking there, far south in North America — more than 3,000 miles in a straight line from the Bering Straits — at the height of the last glacial cycle, when much of those 3,000 miles would have been utterly impassable.
The sediments caught with these prints as the ground hardened included grass seeds called ditch grass. That proved critical, because it is through radiocarbon dating of the grass seeds that the footprints have been dated.
Strange New Worlds:
So how long had they — the people who made these footprints — been there? That will have to be thrashed out. It may be a long while before a new consensus forms.