Americas ‘settled in three waves’
The biggest survey of Native American DNA has concluded that the New World was settled in three major waves.
But the majority of today’s indigenous Americans descend from a single group of migrants that crossed from Asia to Alaska 15,000 years ago or more.
Previous genetic data have lent support to the idea that America was colonised by a single migrant wave.
An international team of researchers have published their findings in the journal Nature.
“For years it has been contentious whether the settlement of the Americas occurred by means of a single or multiple migrations from Siberia,” said co-author Prof Andres Ruiz-Linares from University College London (UCL).
“But our research settles this debate: Native Americans do not stem from a single migration. Our study also begins to cast light on patterns of human dispersal within the Americas.”
The team analysed data from 52 Native American and 17 Siberian groups, studying more than 300,000 variations in their DNA known as Single Nucleotide Polymorphisms, or SNPs.
This allowed them to examine patterns of genetic similarities and differences between the population groups …
The team also found that once in the Americas, people expanded southward along a route that hugged the coast, with populations splitting off along the way.
After their divergence, there was little gene flow among Native American groups, especially in South America.
Two glaring exceptions to this simple dispersal were also discovered. First, Central American Chibchan-speakers have ancestry from both North and South America, reflecting a migration back from South America to Central America.
Second, the Naukan and coastal Chukchi from north-eastern Siberia carry distinctive “First American” DNA. Thus, Eskimo-Aleut speakers migrated back to Asia, bringing Native American genes.
The team’s analysis was complicated by the influx into the hemisphere of European and African immigrants since 1492 and the 500 years of genetic mixing that followed …
Read Whole: BBC News
