New dates for Monte Verde pushes back arrival of first humans in South America

Chilean site was first occupied at least 18,500 years ago

Monte Verde in southern Chile is a peat bog in the terraces of Chinchihuapi Creek in the Maullín river basin, midway between the Pacific coast and the Andean mountains. There is well-preserved evidence of human occupation including wooden tent remains, foundations and floors of huts, hearths, wooden lances, mortars, and large numbers of stone tools. The site was apparently occupied all year round. A wide range of coastal and mountain habitats were exploited including marshes, wetlands, forests, estuaries, and rocky and sandy shorelines.

Evidence of habitation was not thought to pre-date the 14,600 year horizon identified at the site MV-II, although there was evidence of an earlier cultural horizon (MV-I). The MV-II dates in themselves made Monte Verde attractive to opponents of the long-running ‘Clovis First’ orthodoxy, which holds that the culture originally identified at Clovis, New Mexico represents the earliest human settlement of the New World. The Clovis culture is noted for its distinctive leaf-shaped spear points, which were first found in the 1930s. Clovis sites dating from 13,250 years ago are widespread across the United States and Central America to as far south as Panama. Assuming that the first Americans reached the New World via the Beringia land bridge that linked Alaska with Siberia during the last Ice Age, a human presence in South America 14,600 years ago is problematic to Clovis First.

However, even earlier dates have now been obtained for Monte Verde. Archaeologists carried out spatially-intermittent excavations and core drillings across an area lying between MV-II and the two sites of CH-I and CH-II, located on the south side of the creek, 500 m upstream of MV-II. These revealed stone tools, faunal remains, and evidence of fires widespread across the study area albeit vertically and horizontally discontinuous. These appear to represent ephemeral seasonal activities carried out over a long period of time between shallow channels of a now-buried braided system of streams that fed into the river. Radiocarbon and Optically Stimulated Luminescence dating has yielded a range of dates from 18,500 to 14,500 years ago, with implications that humans reached the New World much earlier than previously believed.

Reference:
Dillehay, T. et al., New Archaeological Evidence for an Early Human Presence at Monte Verde, Chile. PLoS One 10 (11) (2015).

 

 

Prehistory of New World Arctic investigated in major new genetic study

Paleo-Eskimos were independent of Inuit and Native American expansions

In the 1980s, the American linguist Joseph Greenberg proposed that Native American languages could be classified within three families: Eskimo-Aleut, Na Dene and Amerind. He further suggested that each family corresponded to a separate migration into the New World from Siberia and concluded, therefore, that the New World had been peopled by three migrations. Greenberg’s views remained controversial for many years as most mitochondrial and Y-chromosomal genetic studies indicated that there had been no more than two migrations. In 2012, however, he was apparently vindicated when David Reich and his colleagues presented a high resolution study of 52 Native American and 17 Siberian groups genotyped at 364,470 single nucleotide polymorphisms. The results indicated that there had indeed been three migrations broadly corresponding to the three language families: specifically (i) First Americans, (ii) Eskimo-Aleuts and, (iii) Saqqaq and Na Dene speakers.

These results are built on by a major new study conducted by an international team numbering over fifty researchers led by geneticist Maanasa Raghavan from the University of Copenhagen. The study focussed on mitochondrial and genome-wide sequences obtained from ancient bone, hair and teeth samples of Arctic Siberia, Alaska, Canada, and Greenland, and high-coverage genomes of two present-day Greenlandic Inuit, two Siberian Nivkhs, one Aleutian Islander, and two Athabascan Native Americans.

From this data, researchers hoped to resolve issues regarding the complex archaeological record of the Early Paleo-Eskimos (Pre-Dorset/Saqqaq), the Late Paleo-Eskimos (Early Dorset, Middle Dorset, and Late Dorset), and the Thule cultures. They were able to show that the Paleo-Eskimos reached the New World in a single migration from Siberia around 3000 BC and displayed genetic continuity for more 4,000 years. About 700 years ago they were replaced by the Thule people, who were the ancestors of the present day Inuit.

While supporting Reich et al overall, the results indicated that the Saqqaq tradition and Na Dene speakers were not part of the same migratory wave: accordingly the Paleo-Eskimos must have arrived in a separate migration to the three waves identified by Reich et al, implying that the New World was populated by four migrations in all.

References:
1.  Reich, D. et al., Reconstructing Native American population history. Nature 488, 370–374 (2012).
2.  Greenberg, J., Turner, C. & Zegura, S., The Settlement of the Americas: A Comparison of the Linguistic, Dental, and Genetic Evidence. Current Anthropology 27 (5), 477-497 (1986).
3.  Raghavan, M. et al., The genetic prehistory of the New World Arctic. Science 345 (620), 1020,1255832 (2014).