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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. |