Just where, when and how the first Homo sapiens sapiens appear in the New World is a matter of some dispute. as to where, most will also agree that the Bering Strait is the most plausible route, though some maintain that a trans Pacific route via Oceana is at least a possibility.
Focusing on the Bering Strait route, there are two possibilities for how -- the manner of arrival:
As to when the time of the first arrival via the Bering Strait route, it is obvious that Homo sapiens sapiens must have been present in northeastern Siberia before crossing the Bering Strait. On the basis of widely accepted views about the diffusion of Homo sapiens sapiens there is no evidence of upper paleolithic presence in northeastern Siberia before 35 Kybp (at the very earliest). This evidence is provided by the Dyukati tradition.
However, the archaeology of this area is not well known and there is good reason to doubt that the Dyukhtai were in fact the same people that first traversed the Bering Strait route. Their stone tool technology characterized by "microblades" is unlike that of the earliest known people in the New World. Thus, the possibility remains that some other, as yet unknown and possibly earlier, inhabitants of northeastern Siberia were the source of the first immigrants to the New World. However, on the basis of currently accepted views of diffusion of Homo sapiens sapiens it is difficult to imagine that they arrived in this area much earlier than 35 Kybp. Presence of Homo sapiens sapiens along either to the plausible routes to northeastern Siberia just does not occur much before this time.
Recent archaeological work ( King and Slobodin '96) in Siberia has revealed fluted projectile points similar to, and roughly contemporaneous with, those of the Paleoindian period in North America. Also of importance to dating the arrival of humans in the New World is the disccovery of evidence for human presence in Siberia as early as 2.6 Kybp ( Waters et al. '97).
Under the hypothesis that the first humans crossed the Bering Strait by boat, they could have crossed at any time after their arrival in northeastern Siberia. Thus, assuming this mode of travel, any evidence of earlier Homo sapiens sapiens presence in northeastern Siberia would make an earlier arrival in the New World more plausible.
Under the hypothesis that the first humans walked across a land bridge, the possible time of arrival is more constrained. There are only two periods during the last 100,000 years when it would have been possible to walk across the Bering Strait -- the early Weichsel-Wisconsin glacial (80-45 Kybp) and the full Weichsel-Wisconsin glacial (25-14 Kybp). On the basis of currently accepted views of the diffusion of Homo sapiens sapiens out of Africa, the first period does not appear to be a real possibility. At this time, Homo sapiens sapiens were just beginning to appear in Europe possibly traversing a "land bridge" across the Bosphorus created by the same early Weichsel-Wisconsin glacial that produced the "land bridge" across the Bering Strait. Thus, if the first immigrants to the New World walked across the Bering Strait, the must have done it during the 25-14 Kybp period and they could not have arrived before the emergence of the "land bridge" at 25 Kybp.
