This was startling for a simple reason: the Mal’ta boy was found in Siberia.

Native Americans — the Indigenous peoples of North and South America — were in the Americas.

The two populations were separated by a continent and an ocean.

And yet the genome of a child who had died in Siberia 24,000 years ago carried a genetic signal that appeared, in detectable and meaningful form, in the genomes of Indigenous people living in the Western Hemisphere.

The explanation, as researchers worked through its implications over the years following the initial 2013 publication, involved a revision of what scientists had understood about the founding of the Americas.