Excavations of South American sites containing traces of ancient human activity have suggested that humans reached the southern region of the continent at least 14,500 years before present (BP)—remarkably quickly after first entering the Americas—and that they soon developed diverse technologies across different sites. But the picture yielded by these archaeological investigations is a patchwork, leaving open key questions, such as whether the first humans migrated south along the Pacific coast or by some other route. The history is further complicated by disputed claims (examples marked by red headers with asterisks) that certain sites reflect a much earlier occupation of the continent beginning more than 20,000 BP.
Site: Rock shelter at 4,480 meters in elevation dated to ~12,400 BP
Contains: Remains of plants and animals consumed as food and other human-made debris; human remains; stone tools
Significance: Oldest known site in high Andes; shows humans had adapted to high altitudes
Site: Remains of a seasonally occupied fishing village dated to ~13,000–11,000 BP
Contains: Seafood remnants; hearths; tools made of obsidian and other types of stone
Significance: Demonstrates that people were using marine food sources and, together with Cuncaicha, that coastal people had contact with the Andean highlands
Site: Settlement dated to ~18,500–15,000 BP
Contains: Remains of plants and animals consumed as food; charcoal; wooden artifacts; stone tools
Significance: Pushed back the date of earliest known human occupation of the Americas by as much as 5,000 years
Lapa do Santo
Site: Cave with signs of human activity dated to as early as ~12,700–11,700 BP
Contains: Remains of 50 people, dating as far back as 10,600–9,700 BP, who were buried at the site; stone tools; rock art; animal remnants
Significance: Yielded ancient DNA for analysis and new insight into early cultures
Arroyo del Vizcaíno*
Site: Assembly of more than 1,000 animal bones dated to ~30,000–27,000 BP
Contains: Bones of giant sloths and other large animals, some with apparent cut marks that may indicate they were butchered by humans; purported stone tools
Criticisms include: The bones could have been carried to the site by flowing water rather than human activity; the scenario the authors propose (including human transport of large, killed animals) is not consistent with the way known hunter-gatherer groups operate.
Toca do Sítio do Meio*
Site: Rock shelter with signs of human occupation dated to ~35,000–28,000 BP
Contains: Charcoal remnants; purported stone tools
Criticisms include: Rocks resembling stone tools could have come about through natural geological processes or been made by monkeys.
Genetic insights about the first South Americans
Two studies published in late 2018, one led by David Reich of Harvard University (results depicted in cool colors) and the other by Eske Willerslev of the University of Copenhagen (results in warm colors), compared ancient and modern genomes from across the Americas to infer that there were multiple waves of migration from the northern continent to the southern one.
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Clarification (September 4): The language in this infographic has been updated to reflect the fact that Cuncaicha is the oldest known site in the high Andes, not the Andean region.
Correction (September 8, 2020): The first map has also been updated to correctly denote Monte Verde's location. The Scientist regrets the error.