What is the new widely accepted theory for how humans first arrived in the Americas, if not for the traditional Bering Land Bridge hypothesis?
ianburrell · 5h ago
The new theory is that they came along the coast. Clovis culture arrived 13-16,000 years ago through corridor in ice sheets. But earlier sites, including these footprints, suggest that people arrived another way. These footprints are 21-23,000 years ago. I don't think there is any evidence how they got there, but the coast is plausible explanation.
tempestn · 5h ago
When you say "the coast", do you mean travelling south down the Pacific coast after crossing the Bering land bridge?
There is also evidence that pacific Islanders made at least two trips to the Americas using rafts.
I believe generic testing shows pacific Islander and early Asian DNA mixing.
Stefan Milo on YouTube has a few videos looking into different theories.
tiahura · 2h ago
The Pacific Islanders didn’t get to Tahiti and Hawaii until 1000AD.
m0llusk · 4h ago
There is genetic evidence linking these very old inhabitants to Pacific Islanders of that time and there were more islands at that time because of lower sea levels.
AlotOfReading · 3h ago
It's really confusing to use the term pacific islanders here. The farthest humans had reached was the Solomon Islands, what we call "near Oceania". The places people think of when they say "Pacific Islands", namely Remote Oceania (Melanesia), Micronesia, and Polynesia were all uninhabited. Those early Papuans weren't especially closely related to the founding populations of the Americas, though they're closer than you might expect from the geographic distance because of the serial founder effect.
advisedwang · 5h ago
My lay understanding is that the theory is that these earlier humans crossed the Bering land bridge but that they didn't proceed through a inland ice-free corridor (as there was none then). They likely traversed the pacific coast, which was not at the same position it is today and so would leave no evidence.
I have also seen discussion of sea arrivals, but they are much more hypothetical.
Also worth noting as the earlier arrival doesn't rule out the later ice-free corridor traversal as having also happens - it just means it wasn't the first people to arrive in the Americas.
MangoToupe · 2h ago
In addition to what other people have indicated, there's a long tale of competing theories. There's very limited evidence of human settlement in the old crow flats as far back as 40kya (which is still 20kya after the settlement of australia), but unfortunately this evidence (butchered animal bones) are circumstantial and the dating is not reliable.
However, i think ~23kya is a pretty safe bet at this point. And there are dozens of sites before 14kya as far south as chile. Clovis first has been largely rejected for about 30 years now but the old narratives keep floating around.
o11c · 5h ago
It's not that different. There's just dispute over when exactly between 30kya and 11kya people first crossed.
fshafique · 2h ago
I like the Battlestar Galactica theory for this - a group of humans and human-Cylon hybrids bred with the early Neanderthals in different regions of the world.
AlotOfReading · 2h ago
To put it bluntly, we don't have a good theories to explain the white sands timeline.
There have been a few major explanations that overlap in parts:
1) The Ice-Free Corridor, which was closed from 26-14ka. This is the old, traditional theory from the 50s-60s. It survived the widespread recognition of pre-clovis cultures with sites like Monte Verde (~13ka) because the dates hadn't been refined to where they are today. It's been considered dead for awhile now though, but potentially up for a resurrection with how far back the white sands dates are.
2) Pacific Coastal Migration Hypothesis. Around 30-25ka, coastal foragers from somewhere between Japan and Kamchatka migrated east along the Alaskan coast, living off a combination of terrestrial and marine resources in the relatively mild climate of the coast. This assumes the existence of ice free coastal refugia where people, animals, and plants were able to live during the last glacial maximum (LGM). So far, we have little to no evidence to suggest that these existed. More work needed to understand fine-scale glaciation of the Alaskan coast during the LGM. Additionally, the Alaskan current is thought to have been extremely strong during this period, potentially impossible to sail against. Again, better climate modeling needed. This is the de-facto explanation because we don't have anything better, but it's not something anyone's happy with.
3) Beringia standstill Hypothesis. Usually seen in combination with one of the previous two, but the idea is that humans inhabited inland Beringia until relatively recently and then proceeded into the subarctic Americas by one of the other routes. This works well with the genetic data, but the IFC hypothesis is basically dead and it excludes the earlier entry. The later date doesn't work with preclovis archaeology. Access to the pacific coastal route seems to be prevented by glaciation along the southern alaskan coast until later than the genetic data would indicate, so this not a well-explored hypothesis. Better climate modeling needed.
4) The kelp highway hypothesis. Basically similar to the coastal migration hypothesis, with less emphasis on terrestrial resource use. It has many of the same problems and you'll sometimes see people group them together with a term like "Pacific Coastal Route". The society this hypothesis requires doesn't look like any culture we've observed anthropologically. It's not especially compatible with available genetic data (though this can be somewhat explained). It's not well supported by archaeological evidence, either. It's not widely discussed on its own.
You can tell those feet had toes that were much longer and stronger than modern toes are. Makes sense since these creatures were closer back to when we were like monkeys climbing thru trees.
speakspokespok · 2h ago
Probably not. :)
However, I do notice the pronounced gaps between the toes. My parents generation grew up in Melanesia starting around the 1950’s and many of them have commented on the distinctly different footprint profiles of the local people who never had worn shoes and the western newcomers. If you’ve never worn shoes your toes are far more splayed. I don’t know about lenght of toe.
So really I don’t think your observation is related to their genetic proximity and more to do with bodily adaptation. Perhaps an anthropological podiatrist can comment.
For context, how old are the oldest Egyptian pyramids?
kcplate · 54m ago
> If you’ve never worn shoes your toes are far more splayed.
After 7 years of remote work and living in a warm climate where I rarely wear shoes, I can confirm that my own toes have splayed out.
quantadev · 1h ago
Women's feet have grown 30% since 1960. Look it up. Doesn't mean the trend will continue, it just means evolution can indeed happen very rapidly under certain circumstances, and for primates to keep long toes for a very long time even after coming down from the trees makes some sense. Probably much more efficient to run thru mud, etc.
AlotOfReading · 16m ago
I don't know why you're on about this, but our foot shape has been essentially static across the entirety of genus Homo. The difference in time between us and them is an imperceptible rounding error compared to the many millions of years since bipedalism evolved. These people looked like us, wore clothes, spoke languages, etc. If you teleported one of their infants forward and raised it, it would be virtually indistinguishable from a modern person until you did genetic testing.
AlotOfReading · 3h ago
These were anatomically modern humans, essentially identical to you or I.
IncreasePosts · 3h ago
Maybe ultra modern humans have toes stunted from non-stop shoe wearing. You definitely splay your toes more if you're accustomed to walking bare foot than you do if you're accustomed to walking in shoes.
quantadev · 59m ago
I'm not talking about splay bro. Length. Size matters. bwahaha.
binary132 · 2h ago
23,000 years is really not a meaningful distance at all in terms of evolutionary timescales.
quantadev · 1h ago
Sure it is. Especially when talking about relative sizes of existing anatomy rather than completely new anatomy.
For example: Women's feet have gotten considerably larger over the past several decades. For example, in the 1960s, the average size was around a 6.5, in the 1970s it was 7.5, and today it's often cited as between 8.5 and 9. That's a whopping 30% (according to Gemini) increase in them whoppers, in my lifetime alone.
I think it's well know also that when there's a certain type of environmental condition that puts different stressors on something evolution can happen only in a few generations. Look it up. There's countless examples of rapid evolution that's well known to happen.
MangoToupe · 2h ago
This comment made me belly laugh. Wtf?
quantadev · 1h ago
Look at the feet of a monkey. They're basically long fingers. That's what I'm getting at.
Edit: ah, the earlier discussion covers this: https://news.ycombinator.com/item?id=44319585
I believe generic testing shows pacific Islander and early Asian DNA mixing.
Stefan Milo on YouTube has a few videos looking into different theories.
I have also seen discussion of sea arrivals, but they are much more hypothetical.
Also worth noting as the earlier arrival doesn't rule out the later ice-free corridor traversal as having also happens - it just means it wasn't the first people to arrive in the Americas.
However, i think ~23kya is a pretty safe bet at this point. And there are dozens of sites before 14kya as far south as chile. Clovis first has been largely rejected for about 30 years now but the old narratives keep floating around.
There have been a few major explanations that overlap in parts:
1) The Ice-Free Corridor, which was closed from 26-14ka. This is the old, traditional theory from the 50s-60s. It survived the widespread recognition of pre-clovis cultures with sites like Monte Verde (~13ka) because the dates hadn't been refined to where they are today. It's been considered dead for awhile now though, but potentially up for a resurrection with how far back the white sands dates are.
2) Pacific Coastal Migration Hypothesis. Around 30-25ka, coastal foragers from somewhere between Japan and Kamchatka migrated east along the Alaskan coast, living off a combination of terrestrial and marine resources in the relatively mild climate of the coast. This assumes the existence of ice free coastal refugia where people, animals, and plants were able to live during the last glacial maximum (LGM). So far, we have little to no evidence to suggest that these existed. More work needed to understand fine-scale glaciation of the Alaskan coast during the LGM. Additionally, the Alaskan current is thought to have been extremely strong during this period, potentially impossible to sail against. Again, better climate modeling needed. This is the de-facto explanation because we don't have anything better, but it's not something anyone's happy with.
3) Beringia standstill Hypothesis. Usually seen in combination with one of the previous two, but the idea is that humans inhabited inland Beringia until relatively recently and then proceeded into the subarctic Americas by one of the other routes. This works well with the genetic data, but the IFC hypothesis is basically dead and it excludes the earlier entry. The later date doesn't work with preclovis archaeology. Access to the pacific coastal route seems to be prevented by glaciation along the southern alaskan coast until later than the genetic data would indicate, so this not a well-explored hypothesis. Better climate modeling needed.
4) The kelp highway hypothesis. Basically similar to the coastal migration hypothesis, with less emphasis on terrestrial resource use. It has many of the same problems and you'll sometimes see people group them together with a term like "Pacific Coastal Route". The society this hypothesis requires doesn't look like any culture we've observed anthropologically. It's not especially compatible with available genetic data (though this can be somewhat explained). It's not well supported by archaeological evidence, either. It's not widely discussed on its own.
However, I do notice the pronounced gaps between the toes. My parents generation grew up in Melanesia starting around the 1950’s and many of them have commented on the distinctly different footprint profiles of the local people who never had worn shoes and the western newcomers. If you’ve never worn shoes your toes are far more splayed. I don’t know about lenght of toe.
So really I don’t think your observation is related to their genetic proximity and more to do with bodily adaptation. Perhaps an anthropological podiatrist can comment.
For context, how old are the oldest Egyptian pyramids?
After 7 years of remote work and living in a warm climate where I rarely wear shoes, I can confirm that my own toes have splayed out.
For example: Women's feet have gotten considerably larger over the past several decades. For example, in the 1960s, the average size was around a 6.5, in the 1970s it was 7.5, and today it's often cited as between 8.5 and 9. That's a whopping 30% (according to Gemini) increase in them whoppers, in my lifetime alone.
I think it's well know also that when there's a certain type of environmental condition that puts different stressors on something evolution can happen only in a few generations. Look it up. There's countless examples of rapid evolution that's well known to happen.