Cave discoveries suggest humans reached Americas much earlier than thought

https://www.nature.com/articles/d41586-020-02190-y

by pseudolus • 6 years ago

106 38 6 years ago

walrus012• 6 years ago

An interesting question related to this is the exact time period of the "last glacial maximum", at which point in time northern latitude glaciers were at their maximum extent, and sea levels were considerably lower. Related to the Bering strait land bridge.

https://en.wikipedia.org/wiki/Last_Glacial_Period

https://en.wikipedia.org/wiki/Last_Glacial_Maximum

If the claim of 30,000 years is true (vs 11,000 years) this would mean people crossed the Bering strait at a time when the terrain was different, or possibly even when it was submerged.

https://en.wikipedia.org/wiki/Beringia

brohee3• 6 years ago

Hoping along the Commander Islands, Near Islands then Aleutian Islands chain from Kamchatka was likely possible with primitive tech. And those places must have been hunting paradises to neolithic people so reasons to settle them.

walrus012• 6 years ago

One of the interesting things I learned in my cursory and brief research of this. Proponents of the theory of migration 10,000 to 12,000 point out that at the glacial maximum, the strait is theorized to have been a grassland. Part of their theory is that people could not have crossed beforehand because of the absence of animals to hunt and eat along the way.

I'm not sure how much I believe that the presence of grasslands would be an absolute requirement. In an island hopping theory, killing and eating seals and other beach dwelling large mammals seems equally plausible.

ncmncm4• 6 years ago

Humans made it to Australia without any Land Bridge. Island hopping is completely plausible: once you have crossed one waterway, the next is easier.

We know that populations of humans subsisted on coastal shellfish 50kya. There is no reason to assume they stayed at one place on a coast that had shellfish everywhere along it.

Of course all those shell middens are now 30-50m below sea level.

If there is an Atlantis, that is, too, for identically the same reason, although the timing would differ. It would be hard to credit an Atlantis originating before, say, 12,000 years ago--sometime in the Younger Dryas cold spell--although up to 20,000 years ago is conceivable.

mehrdadn• 6 years ago

Question: how do experts tell something like this might be a tool? As a layman it looks like a rock to me:

https://media.nature.com/lw800/magazine-assets/d41586-020-02...

oxfordmale• 6 years ago

These kind of tools have multiple fracture all running in the same direction. This means they are not a by product of accidentally tumbling against other rocks. Something has banged that rock over and over in the same position.

DanBC• 6 years ago

I think they look for "Conchoidal fractures", and then where they find the thing.

https://www.sandatlas.org/conchoidal-fracture/

082349872349872• 6 years ago

I haven't tried knapping yet myself, but it apparently takes planning several flakes in advance, because one needs to leave well-positioned striking platforms for each flake.

Single-click shopping sounds much less mentally taxing than stone age technology.

https://peterborougharchaeology.org/archaeology-skills-techn...

http://www.pugetsoundknappers.com/how_to/how_to_instruction/...

AlotOfReading• 6 years ago

Not always, but it's one of the common indicators. The general process for survey identification goes like this: you walk around looking at the ground and notice the unnatural ones. This is a purely intuitive sense, so you pick one up and look closer to see that yep straight edges, conchoidal fractures, common material, found in a bed with other clear lithics, etc. Bag and tag.

singularity2001• 6 years ago

“If an artefact is a stone tool, you see numerous chips removed from the edge,” says Rademaker. He sees no clear evidence of this in the images in the paper — a point echoed by archaeologist Ben Potter at Liaocheng University in China.

mcswell3• 6 years ago

See my comment above (made before I read yours :-() asking whether cutting tools would ever have been made out of limestone.

simonh4• 6 years ago

The examples in that article are pretty poor, possibly selected because someone is shown handling them. Here’s a more comprehensive selection of tools from the same site.

http://www.sci-news.com/archaeology/stone-tools-chiquihuite-...

sradman6• 6 years ago

From the linked Wikipedia article on Beringia [1]:

Today, the average water depth of the Bering Strait is 40–50 m (130–160 ft), therefore the land bridge opened when the sea level dropped more than 50 m (160 ft) below the current level. A reconstruction of the sea-level history of the region indicated that a seaway existed from c. 135,000 – c. 70,000 BP, a land bridge from c. 70,000 – c. 60,000 BP, intermittent connection from c. 60,000 – c. 30,000 BP, a land bridge from c. 30,000 – c. 11,000 BP, followed by a Holocene sea-level rise that reopened the strait.

30-25 kya fits the data OK and there may have been open north-south corridors at that time. The question is how solid the Mexican evidence is.

[1] https://en.m.wikipedia.org/wiki/Beringia#Geography

simonh4• 6 years ago

It seems like there are other bits of evidence of pre-clovis human habitation, but taken individually they could be dismissed as due to some sort of misidentification, contamination of the site, etc. One the other hand this site seems to have very extensive evidence of long term habitation, backed up by several independent but mutually consistent dating methods. Add back in all those 'one off' finds as well and the clovis first theory starts to really break down.

34679• 6 years ago

I've been fascinated by this one since visiting the Natural History Museum in San Diego:

"A 130,000-year-old archaeological site in southern California, USA"

https://www.nature.com/articles/nature22065

api• 6 years ago

Look at Göbekli Tepe as well. The general trend seems to be pushing human history back, which makes sense as the human species has existed in its near modern form for quite a bit longer than the history we know. There is no reason to believe these ancient humans lacked critical cognitive faculties that we have.

From what I've read of the debate on humans in North and South America, it seems that both sides are ignoring the possibility of multiple colonizations and that earlier colonizations may have either failed entirely or resulted in only very small populations in limited areas.

If genetic evidence suggests that Native Americans are descendants of a stock that migrated here around 10K years ago, maybe they were just a later migration that really "took" and expanded across the whole land mass (until Europeans).

Or maybe the newcomers or their diseases exterminated the existing indigenous peoples? Maybe the story of the last colonization of these lands has occurred multiple times? If so, we're really screwed when the extraterrestrials arrive.

mcswell3• 6 years ago

The picture in the article is of an alleged limestone tool; it looks like the tool was shaped like a scraper or cutter of some sort, and is fairly small. But afaik, no one ever made scrapers or cutters out of limestone; that rock is far too soft. They were preferentially made of flint, but in regions where there wasn't flint, obsidian or quartz could substitute for smaller tools, and hard metamorphic or igneous rocks for larger tools (axes).

But surely an archeologist would not make such a mistake. So is my assumption about the uselessness of limestone for cutting tools wrong?

simonh4• 6 years ago

Googling for limestone stone tools came up with plenty of hits, like this one.

https://indianexpress.com/article/technology/science/mysteri...

This article shows a much more comprehensive collection of tools from Chiquihuite.

http://www.sci-news.com/archaeology/stone-tools-chiquihuite-...

mcswell3• 6 years ago

Thanks, but I'm still skeptical.

The first article, in an Indian news site (and reproduced in several similar sites) is about some stones that a group of amateur archeologists found. It doesn't appear to have been published in any professional journal, and the comments make it clear that these are unlike anything seen elsewhere, and their purpose is unknown. My guess: they're not tools, they're random rocks.

The other article, as you point out, shows a greater variety of the alleged tools from Chiquihuite. I'm no archaeologist, but to me they look like rocks that were carefully chosen out of a bunch of randomly shaped rocks. The picture of the cave entrance show that it is full of breakdown (caver for "rocks that fell off the ceiling of the cave"), and I wouldn't be surprised to discover things that look sort of like blades or points in such a pile of rocks.

So I'm afraid I'm still skeptical.

Cave discoveries suggest humans reached Americas much earlier than thought

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