[jcranmer]

The traditional thesis of the peopling of the Americas is that people arrive in Beringia (not entirely accurate to say they crossed the Bering Strait--there was no Bering Strait, and Beringia was where the Bering Strait is now!), c. 20-odd thousand years ago. About 13,000 years ago, a gap opens between the Rocky Mountains and the Laurentide Ice Sheet, and settlers traveled through this "ice-free corridor" to reach what is now the US, where they flourish as the Clovis culture. This is known as the Clovis-First hypothesis--that Clovis was the first material culture to leave Beringia and people the rest of the Americas.

However, there's a lot of evidence that people had spread out to the rest of the Americas well before Clovis, and it's now known that the "ice-free corridor" opens up too late--it opens up even after we see traces of Clovis-First. By around the 1990s, the anthropological community has accepted that Clovis-First is complete and utter rubbish, although there is still disagreement about the timetable. I'd wager seriously arguing Clovis-First among scientists would get you as much derision as seriously arguing geocentrism among astronomers.

Annoyingly, popular anthropology lags science tremendously. It probably took a decade or two for textbook writers to bother to update their textbooks to consider the rejection of Clovis-First (hell, when I was in school, the textbook didn't even bother to present alternative hypotheses than Clovis-First, although our teachers were knowledgeable enough to tell us in class that, well, textbook's got it wrong there), and then perhaps another decade for schools to get around to new textbooks. It's still the case that virtually every popular treatment of some new press release about dating controversy in some ancient human habitation site (there's one every year or so) starts, as this article does, by talking about how it potentially nails the coffin for Clovis-First. (Wake up science writers! That coffin's been nailed shut for longer than most of your readers have been alive!)

[civilitty]

To add to that great explanation: those ice free corridors were important because during the glaciation there were vast expanses of ice with zero vegetation or animal life, making it impossible for humans to cross without starving to death. Those glaciers essentially looked like the South Pole - nothing but ice for hundreds of miles. How humans managed to get so far and colonize so much of the continent while it was still iced over is one of the great "mysteries" of the new world.

It took plants and animals thousands of years to colonize Berengia before it was possible for humans to cross the expanse on land so the main competing hypothesis states that the people of Oceania - at this point very capable of navigating at sea and exploiting marine resources - were the first ones to make the trip, hugging the coast of Beringia to navigate and wait out storms but eating seafood caught at sea to stay alive.

Unfortunately the sea level at this point in time was at least 150 ft below and while underwater archaeology has had somewhat of a renaissance, there's still very little evidence to support what many (most?) archaeologists expect is true: human arrival in the Americas predates any evidence we've recovered by many thousands of years.

[AlotOfReading]

As someone who actively follows this literature, I've never heard of the oceania "theory" put forward by anyone writing in this century. I can think of some very old books by people like Thor Heyerdahl, but they're obviously not remotely legitimate scholarship. What have you read that says it's a mainstream hypothesis?

It doesn't make much sense either, as all of our South American aDNA (e.g. Los Rieles 10900BP) is highly related to other American populations. We also know that boats and marine resource exploitation were used in Northeast Asia prior to the crossing period, given the whole PSHK complex thing (whether or not they're truly ancestral to the first americans). They would have been much better positioned than the people of Oceania, who had just barely colonized the nearest few islands off Sahul and did not leave behind much to suggest particularly advanced marine exploitation at this point.

[civilitty]

Derp! I may be using a more expansive definition of Oceania due to my native language. I think the correct group would be (South) East Asia

[BMorearty]

Thank you. That is a much more lucid and complete explanation than was given in the article.