24 ka Americans?

About 24 ka ago, when much of North America was buried under the ice of the Last Glacial Maximum, a few hunters took shelter in a small cave above the Bluefish River in what is now northwestern Yukon. The hunters had killed a Yukon horse and were butchering it using super-sharp stone shards called microblades. As they sliced out the horse’s meaty tongue, the microblades left distinctive cuts in its jaw bone. Millennia later, archaeologist and doctoral candidate Lauriane Bourgeon spotted those marks through her microscope at the University of Montreal and added the fragment of ancient jaw bone to her small selection of samples for radiocarbon dating.

2017-04-26: 130 ka Americans? Those are fighting words, 6x-10x earlier than generally believed. Needs a LOT more evidence.

An unidentified Homo species used stone tools to crack apart mastodon bones, teeth and tusks approximately 130 ka ago at a site near what’s now San Diego.

2021-11-13: There’s plenty of evidence that North America was settled early, but not successfully:

The problem with the idea of an early, pre-Amerindian settlement of the Americas is that ( by hypothesis, and some evidence ) it succeeded, but ( from known evidence) it just barely succeeded, at best. Think like an epidemiologist – once humans managed to past the ice, they must have had a growth factor greater than 1.0 per generation – but it seems that it can’t have been a lot larger than that, because if they had averaged, say, 3 surviving kids per generation ( r = 1.5) , their population would have exploded, filling up all the habitable territories south of the glaciers in less than 2 ka. Maybe they didn’t have atlatls. The Amerindians certainly did. Maybe they arrived as fishermen and didn’t have many hunting skills. Those could have been developed, but not instantaneously. An analogy: early Amerindians visited some West Coast islands and must have had boats. But after they crossed the continent and reached the Gulf of Mexico, they had lost that technology and took several 1000 years to re-develop it and settle the Caribbean. Along this line, coastal fishing settlements back near the Glacial Maximum would all be under water today. Maybe they fought among themselves to an unusual degree. I don’t really believe in this, am just throwing out notions. Maybe their technology and skills set only worked in a limited set of situations, so that they could only successfully colonize certain niches. Neanderthals, for example, don’t seem to have flourished in plains, but instead in hilly country. On the other hand, we don’t tend to think of modern human having such limitations. One can imagine some kind of infectious disease that made large areas uninhabitable. With the low human population density, most likely a zoonosis, perhaps carried by some component of the megafauna – which would also explain why it disappeared.

2022-02-08: A more detailed look at the 24 ka hypothesis

I present this history of the last 36 ka of migration from the perspective of a scientist who places genetic evidence in the forefront of the investigation and then tests the models it produces with archaeological, linguistic, and environmental evidence. Around 36 ka BP, a small group of people living in East Asia began to break off from the larger ancestral populations in the region. 25 ka BP, the smaller group in East Asia itself split into 2. 1 gave rise to a group referred to by geneticists as the ancient Paleo-Siberians, who stayed in Northeast Asia. The other became ancestral to Indigenous peoples in the Americas.

24 ka BP, both groups independently began interacting with an entirely different group of people: the ancient Northern Siberians. Some archaeologists and geneticists argue that this meeting of the 2 grandparent populations of Native Americans—the group in East Asia and the ancient community in Northern Siberia—occurred because people moved north, not south, in response to the last glacial maximum (LGM), a period in which much of northern North America was covered by massive glaciers. Thus, many geneticists look north, to Beringia, for the location of the refugia that may have allowed the ancestors of Native Americans to survive the ice age.

2022-08-14: 37 ka evidence

About 37ka BP, a mother mammoth and her calf met their end at the hands of human beings.

Bones from the butchering site record how humans shaped pieces of their long bones into disposable blades to break down their carcasses, and rendered their fat over a fire. But a key detail sets this site apart from others from this era. It’s in New Mexico – a place where most archaeological evidence does not place humans until 10s of 1000s of years later. Based on genetic evidence from Indigenous populations in South and Central America and artifacts from other archaeological sites, some scientists have proposed that North America had at least 2 founding populations: the Clovis and a pre-Clovis society with a different genetic lineage.