This week we report on the genome sequence of a boy from 12,600 years ago whose family were ancestral to all Native American groups, from both North and South America. The find offers an unparalleled opportunity to understand how the Americas were first colonised (see “Ancestry of first Americans revealed by a boy’s genome“).
Archaeologists have accumulated a great deal of information about the early settlement of the Americas. Here we examine the most important archaeological sites, beginning with the first discoveries.
The story begins at this site near Clovis, New Mexico. Here in 1932, archaeologists found masses of animal bones mixed with long, slender stone spear points.
By the 1960s, plenty of Clovis points had been discovered, but there were no remains of the people who made them. That changed in 1968. At the Anzick site in Montana, construction work revealed what is still the only known Clovis burial: a three-year-old child who died about 12,600 years ago.
For decades, archaeologists believed that the Clovis people were the first Americans, arriving via an ancient land bridge between Siberia and Alaska and then making their way south. But the story never quite fit. Even as the first Clovis tools were being found at Blackwater Draw, other archaeologists were discovering evidence of ancient human activity in Chile at about the same time as the Clovis culture.
With Monte Verde, discovered in the 1970s, Chilean archaeology went one better. The site dates back at least 14,200 years, long before any Clovis site. This led many archaeologists to conclude that the Clovis were not the first Americans, and that there was a pre-Clovis culture.
However, the new genetic evidence reinforces the importance of the Clovis people. Sites like Monte Verde do suggest that people left eastern Russia to colonise the Americas long before the Clovis, at least 14,200 years ago. But the genetics tells us that the Clovis were close relatives of these American pioneers, perhaps having split from the first migrants early on (see “Ancestry of first Americans revealed by a boy’s genome“).
The mystery of the first Americans has thrown up a few red herrings.
In the 1970s, a trawler working Oyster Cove in Chesapeake Bay on America’s east coast dredged up ancient stone tools and mammal fossils. The tools, and others like them found onshore, are superficially similar to those made by humans living in western Europe. This led to the theory that the first Americans came from Spain, not Siberia. The idea is dismissed by most researchers.
Then in 2003, 40,000-year-old human footprints found in volcanic ash near Puebla in Mexico suggested that the New World was colonised far earlier than anyone thought. But later work showed that the ash solidified 1.3 million years ago, long before our species even evolved. Everyone now agrees that the footprints were not really footprints.
Kennewick Man is a 9500-year-old human skeleton found in 1996 in Kennewick, Washington. The skeleton has arguably done little so far to change our picture of New World colonisation. But it is a crucial part of the story because its discovery was a flashpoint in the ongoing clash between Native American tribes in the US and the scientists studying their origins.
There was a nine-year-long legal battle to decide whether the remains could be studied at all, or whether cultural ties meant that they should be passed to Native Americans for reburial. In 2004 a federal appeals court granted researchers permission to continue their work. Relationships between scientists and Native American tribes have never really recovered.
In the last decade, signs of pre-Clovis activity have turned up in the US. They were the final nail in the coffin for the idea that the Clovis people were the first Americans. Among the most convincing pre-Clovis sites is Buttermilk Creek in central Texas. Crude tools found here between 2006 and 2009 are at least 15,500 years old – even older than Monte Verde.
Between 2008 and 2011, a hoard of 12,000-year-old stone tools turned up on Santa Rosa, one of the Channel Islands of California. Unexpectedly, they were nothing like the distinctive Clovis points that date to this time elsewhere in the US. The Clovis people were apparently not the only group living in North America 12,000 years ago. The immediate question was, how were the two groups related?
An answer was not long in coming. Around this time, 52 native groups living in North, Central and Southern America donated their DNA to geneticist David Reich of Harvard Medical School in Boston, to help answer questions about New World colonisation. No US Native Americans donated their DNA because of their ongoing mistrust of the scientists.
But even without the US input, in 2012 Reich was able to establish that the first Americans came across from Siberia in three related waves. One rapidly spread south down the west coast into Central and Southern America, while the two later waves remained in the north.
A 14,300-year-old latrine found in the Paisley Caves of Oregon may have been left by humans belonging to the first wave. Its discovery cast more doubt on the idea that the Clovis people were the first Americans, because stone tools found near the ancient human faeces were quite different from Clovis points.
The theory goes that the Paisley tools, and those on Santa Rosa, belonged to human groups that clung to the coast and rapidly spread southwards, consistent with the genetic data. But the tools are so distinct from Clovis points that it is unclear how, or even if, the Clovis people fit into this first wave of New World colonisation.
Today’s findings take the story of the First Americans almost full circle, and help tie down the Clovis people’s place in prehistory. At just 12,600 years old, the Anzick child’s remains are younger than the Paisley Caves faeces or sites like Monte Verde. But genetically he is clearly a member of the first wave of colonisation that Reich identified in 2012 from modern genes.
We now know for sure that the Clovis people were not the first Americans. But the Anzick child confirms they were closely related to them (see “Ancestry of first Americans revealed by a boy’s genome“).
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