Archaeological support for the three-stage expansion of modern humans across northeastern Eurasia and into the Americas.
BACKGROUND
Understanding the dynamics of the human range expansion across northeastern Eurasia during the late Pleistocene is central to establishing empirical temporal constraints on the colonization of the Americas. Opinions vary widely on how and when the Americas were colonized, with advocates supporting either a pre- or post- last glacial maximum (LGM) colonization, via either a land bridge across Beringia, a sea-faring Pacific Rim coastal route, a trans-Arctic route, or a trans-Atlantic oceanic route. Here we analyze a large sample of radiocarbon dates from the northeast Eurasian Upper Paleolithic to identify the origin of this expansion, and estimate the velocity of colonization wave as it moved across northern Eurasia and into the Americas.


RESULTS
We use diffusion models to quantify these dynamics. Our results show the expansion originated in the Altai region of southern Siberia approximately 46kBP , and from there expanded across northern Eurasia at an average velocity of 0.16 km per year. However, the movement of the colonizing wave was not continuous but underwent three distinct phases: 1) an initial expansion from 47-32k calBP; 2) a hiatus from approximately 32-16k calBP, and 3) a second expansion after the LGM approximately 16k calBP. These results provide archaeological support for the recently proposed three-stage model of the colonization of the Americas. Our results falsify the hypothesis of a pre-LGM terrestrial colonization of the Americas and we discuss the importance of these empirical results in the light of alternative models.


CONCLUSIONS
Our results demonstrate that the radiocarbon record of Upper Paleolithic northeastern Eurasia supports a post-LGM terrestrial colonization of the Americas falsifying the proposed pre-LGM terrestrial colonization of the Americas. We show that this expansion was not a simple process, but proceeded in three phases, consistent with genetic data, largely in response to the variable climatic conditions of late Pleistocene northeast Eurasia. Further, the constraints imposed by the spatiotemporal gradient in the empirical radiocarbon record across this entire region suggests that North America cannot have been colonized much before the existing Clovis radiocarbon record suggests.
Hamilton
Marcus J
MJ
Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America. marcusj@unm.edu
Buchanan
Briggs
B
D000569:Americas; D000704:Analysis of Variance; D001106:Archaeology; D001208:Asia; D004058:Diffusion; D004641:Emigration and Immigration / Q000706:statistics & numerical data*; D005060:Europe; D006801:Humans; D008962:Models, Theoretical; D055110:Radiometric Dating; D012044:Regression Analysis; D013997:Time Factors
Ann Hum Genet. 2005 Jan;69(Pt 1):67-89
15638829
PLoS Biol. 2005 Jun;3(6):e193
15898833
J Hum Evol. 2004 Jul-Aug;47(1-2):3-17
15288521
J Hum Evol. 2008 Nov;55(5):772-81
18922563
Proc Natl Acad Sci U S A. 2009 Jul 28;106(30):12261-6
19620737
J Hum Evol. 2000 Jun;38(6):803-25
10835263
Trends Ecol Evol. 2007 Apr;22(4):180-4
17157408
Am J Phys Anthropol. 2007 Apr;132(4):605-21
17243155
PLoS One. 2008 Feb 13;3(2):e1596
18270583
Am J Hum Genet. 2008 Jul;83(1):142-6; author reply 146-7
18606310
PLoS Biol. 2005 Dec;3(12):e410
16292981
Curr Biol. 2010 Feb 23;20(4):R202-7
20178768
J Hum Evol. 2009 Jul;57(1):91-5
19539978
Science. 1990 Aug 24;249(4971):937-8
17773106
Science. 2007 Feb 23;315(5815):1122-6
17322060
Proc Natl Acad Sci U S A. 1997 Mar 4;94(5):1866-71
9050871
Nature. 2006 Feb 23;439(7079):931-5
16495989
Hum Biol. 2009 Apr;81(2-3):121-40
19943740
Proc Natl Acad Sci U S A. 2007 Oct 2;104(40):15625-30
17898176
Science. 2004 Jan 2;303(5654):52-6
14704419
Trends Ecol Evol. 2009 Sep;24(9):515-21
19682765
Science. 2008 Mar 14;319(5869):1497-502
18339930
Trends Genet. 2006 Feb;22(2):79-83
16356585
PLoS One. 2007 Sep 05;2(9):e829
17786201
PLoS One. 2008 Sep 17;3(9):e3157
18797501
PLoS One. 2009;4(1):e4210
19148289
Nature. 2000 Dec 7;408(6813):708-13
11130070
Am J Phys Anthropol. 1996 Sep;101(1):1-9
8876810
PLoS One. 2008 Sep 17;3(9):e3199
18797500
Nature. 2006 May 11;441(7090):207-9
16688174
Nature. 2001 Sep 6;413(6851):64-7
11544525