Coastal environments during the Last Glacial Maximum were complex.
Estimates of the final re-submergence of the Beringian land bridge based purely on present bathymetry of the Bering Strait and eustatic sea level curve place the event around 11,000 years BP (Figure 1).
Ongoing research reconstructing Beringian paleogeography during deglaciation could change that estimate and possible earlier submergence could further constrain models of human migration into North America.
The continents of North and South America were settled by Indigenous peoples from Asia between 10 and 20 thousand years ago after they crossed a land bridge that formed between northeastern Siberia and western Alaska due to the lowering of sea level during the last ice age.
Available scientific evidence indicates that modern humans emerged from Africa over 100,000 years ago, yet did not arrive in the Americas until less than 20,000 years ago.
However, archaeosites that date closer to the Last Glacial Maximum on either the Siberian or the Alaskan side of Beringia are lacking.
Recent studies of Amerindian genetics have used high resolution analytical techniques applied to DNA samples from modern Native Americans and Asian populations regarded as their source populations to reconstruct the development of human Y-chromosome DNA haplogroups (y DNA haplogroups) and human mitochondrial DNA haplogroups (mt DNA haplogroups) characteristic of Native American populations.Alpine glaciers in the coastal ranges and the Alaskan Peninsula isolated the interior of Beringia from the Pacific coast.Coastal alpine glaciers and lobes of Cordilleran ice coalesced into piedmont glaciers that covered large stretches of the coastline as far south as Vancouver Island and formed an ice lobe across the Straits of Juan de Fuca by 15,000 Prior to the Last Glacial Maximum, climates in eastern Siberia fluctuated between conditions approximating present day conditions and colder periods.The uncertainty is fed by a lack of archaeological evidence along migration routes that date to the periods when those migrations are proposed to have occurred; uncertainties in the dating and interpretation of the oldest proposed archaeosites in the Americas; and uncertainties of assumptions underlying chronological and source models of migration derived from studies of modern Native American genetics.are the archaeosites in the Americas with the oldest dates that have gained broad acceptance.Stones described as probable tools, hammerstones and anvils, have been found in southern California, at the Cerutti Mastodon site, that are associated with a mastodon skeleton which appeared to have been processed by humans.