Ancient DNA maps three waves of Indigenous American arrival and a ghost lineage

An international analysis of 128 Indigenous American genomes from across the Americas reveals three migration waves into South America: the earliest over 9,000 years ago, a second lineage around that period, and a previously unrecognized dispersal at least 1,300 years ago linked to Mesoamerica. Researchers also identify a faint Asian “ghost lineage” called Ypykuéra that contributed genes to Indigenous Americans and early Australasians, indicating a more complex peopling of the continents. Indigenous genomes are less diverse than those of other continents but harbor adaptive genes related to immune function, metabolism, and fertility, underscoring environmental pressures and the importance of including Indigenous communities in genomic studies.