section_path: Genetics
section_name: Genetics
paragraph_text: Genetics
  
  The haplogroup most commonly associated with Indigenous Amerindian genetics is Y-chromosome haplogroup Q1a3a. Researchers have found genetic evidence that the Q1a3a haplogroup has been in South America since at least 18,000 BCE. Y-chromosome DNA, like mtDNA, differs from other nuclear chromosomes in that the majority of the Y-chromosome is unique and does not recombine during meiosis. This has the effect that the historical pattern of mutations can easily be studied. The pattern indicates Indigenous peoples of the Americas experienced two very distinctive genetic episodes: first with the initial peopling of the Americas and second with European colonization of the Americas. The former is the determinant factor for the number of gene lineages and founding haplotypes present in today's Indigenous populations.
  
  Human settlement of the Americas occurred in stages from the Bering Sea coastline, with an initial 20,000-year layover on Beringia for the founding population. The microsatellite diversity and distributions of the Y lineage specific to South America indicate that certain Amerindian populations have been isolated since the initial colonization of the region. The Na-Dené, Inuit, and Indigenous Alaskan populations exhibit haplogroup Q-M242 (Y-DNA) mutations, however, and are distinct from other Indigenous peoples with various mtDNA mutations. This suggests that the earliest migrants into the northern extremes of North America and Greenland derived from later populations.