The new genomic analysis was made possible by the excavation and recovery of ancient human remains -- some date to 11,000 years ago -- featuring well-preserved DNA. Photo by André Strauss/UNM
Nov. 15 (UPI) -- Ever since the earliest humans left Africa, the human story has been one of movement.
"Humans are global travelers, we've left home and moved onward for as long as humans have been on the planet," Keith Prufer, professor of anthropology at the University of New Mexico, told UPI.
Now, scientists have a better understanding of how humans moved into South America. New genomic research has revealed two previously unknown human migrations from North to South America, which means South America was peopled by at least four distinct migrations.
"The first one links the oldest individuals from Chile, Brazil and Belize dated between 11,000 and 9,000 years to the oldest individual from [United States], associated to the so-called Clovis culture once largely widespread in North America," Cosimo Posth, researcher at the Max Planck Institute for the Science of Human History, told UPI.
The genomic survey, unprecedented in size and scope, was made possible by ancient DNA collected from 49 individuals in North and South America. One of those individuals is Anzick-1, a Paleo-Indian male infant first recovered from a Montana farm in 1968. Anzick-1 represents the only human remains linked with the Clovis culture.
By comparing the DNA of Anzick-1 with ancient individuals from South America, researchers identified a link between North America's widespread Clovis culture and an early waves of human migration into South America.
The results of the genetic analysis were published in the journal Cell.
"It was previously not known that the Clovis culture extended into South America, and it is incredible that these people were able to migrate all the way throughout North, Central, and South America," Nathan Nakatsuka, a doctoral student at Harvard University, told UPI.
The Clovis migration was followed by three separate influxes of people into various parts of South America.
"Another migration led to the replacement of the Anzick ancestry in most South Americans. A third migration was detected in Southern Peru and northern Chile from 4,200 years ago," Nakatsuka said. "Lastly, there was the Population-Y ancestry related to Papuans and aboriginal Australians that was previously found in some modern Amazonian groups."
All four migrations can be traced to ancestors who crossed the Bering Strait Land Bridge from Asia to the Americas sometime before 15,000 years ago.
Despite these notable migration patterns, the genetic data suggests a remarkable degree of continuity among South American populations.
"Our findings provide greater clarity on the remarkable extent of the relative population continuity in many areas of South America where people up to 9,000 years ago are more closely related to indigenous people currently living in nearby regions relative to those in other regions," Nakatsuka said.
The genetic roots of many indigenous groups can be traced back to the group of migrators that replaced the Clovis culture. But why were Clovis culture groups unable to leave a longterm imprint on the modern genome?
The new research suggests Clovis people were innovative and adaptive. While Clovis people moved through Central America and into South America, bringing along their gene pool, they failed to leave behind the same archaeological signature as their relatives in North America. Researchers surmise the groups adopted new technologies.
"The early Clovis culture migrators likely took their tools with them as they traveled, but as they moved through and into new environments, they would have to adapt those tools and develop new technologies to suit their new environment," Prufer said.
This adaptability wasn't enough to ensure longterm success. Some 9,000 years ago, only a couple thousand years after they arrived, these early Clovis culture groups were replaced by a second group of migrators.
"We have no idea why one of those branches disappeared while the other left in multiple South American regions a genetic impact until today," Posth said.
Like most genomic research, each revelation yields a more complex story of human history. Scientists still need more genetic data to answer new questions about how new groups of migrators interacted with those that came before.
With more digging and cooperation with native peoples in North and South America, researchers hope to answer those questions and inspire new ones.
"We're optimistic that we have identified good locations to look for ancient DNA and will continue build on the story of human migration with new genetic data," Prufer said.