Americas 'Settled In Three Waves' -- BBC
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.
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