Table 1.

Native Americans descend from at least three streams of Asian gene flow

Population groupings tested	P-value for this many Asian streams being enough to explain the data			Minimum number of streams of Asian gene flow needed to explain the data
	1	2	3
E. Greenland Inuit / W. Greenland Inuit / First American	<10−9	0.64	1	2
E. Greenland Inuit / Aleutian / First American	<10−9	0.57	1	2
W. Greenland Inuit / Aleutian / First American	<10−9	0.41	1	2
Chipewyan / E. Greenland Inuit / First American	<10−9	0.02	1	3
Chipewyan / W. Greenland Inuit / First American	<10−9	0.006	1	3
Chipewyan / Aleutian / First American	<10−9	0.03	1	3
Saqqaq / E. Greenland Inuit / First American	<10−9	6×10−6	1	3
Saqqaq / W. Greenland Inuit / First American	<10−9	2×10−6	1	3
Saqqaq / Aleutian / First American	<10−9	0.17	1	2
Saqqaq / Chipewyan / First American	<10−9	0.29	1	2
Saqqaq / Eskimo-Aleut / Chipewyan / First American	<10−9	8×10−6	0.27	3

Notes: We use the method described in Note S6 to test formally whether specified groupings of Native American populations are consistent with descending from 1, 2, or 3 streams of gene flow from Asia. We use “First American” to refer to a pool of 43 populations from Meso-America southward, and “Eskimo-Aleut” to refer to a pool of East and West Greenland Inuit and Aleuts. We test either 3 or 4 population groupings (when there are 3 groupings, the maximum number of streams we can reject is 2, and so the P-value for 3 streams is always 1). At least two streams of Asian gene flow are required to explain all rows (P<10⁻⁹). The Chipewyan, Eskimo-Aleut and First Americans can only be jointly explained by at least three streams. Analysis of the Saqqaq Paleo-Eskimo (using ~6-fold fewer SNPs than for the other analyses) show that the Asian ancestry in this individual has a component that is different from that in First Americans and Greenland Inuit, but indistinguishable from the Chipewyan.