Modern humans are thought to have walked out of Africa around 60,000 years ago, and they kept going until they reached every habitable part of the planet. Researchers have now revealed more about the longest migration in human history. Reporting in Science, a new study has indicated that early Asians embarked on the longest prehistory migration of humans in history. This trek was over 20,000 kilometers long (12,427 miles), and took multiple generations of people traveling over thousands of years, as they moved from North Asia to the southernmost part of South America, on foot. Ice bridges are thought to have made this route possible.
This study involved a genetic analysis of over 1,537 individuals who are meant to represent 139 diverse ethnic groups. Patterns of ancestry were analyzed, such as sequences that were shared among individuals, or variations that arose and accumulated over time. These differences and similarities showed how various groups moved, adapted, and split apart as they encountered new environments during their journey from Africa, to North Asia, and finally to Tierra del Fuego in what is now Argentina.
The study found that people got to the northwestern tip of South America about 14,000 years ago. They split into groups after that: some stayed in the Amazon; others moved into an area known as Dry Chaco and some continued onto the ice fields of Southern Patagonia or the peaks and valleys of the Andes.
The work suggested that as people migrated, they also encountered many environmental challenges, which they sometimes overcame.
“Those migrants carried only a subset of the gene pool in their ancestral populations through their long journey. Thus, the reduced genetic diversity also caused a reduced diversity in immune-related genes, which can limit a population’s flexibility to fight various infectious diseases,” noted corresponding study author Kim Hie Lim, an Associate Professor at Nanyang Technological University of Singapore (NTU), among other appointments.
“This could explain why some Indigenous communities were more susceptible to illnesses or diseases introduced by later immigrants, such as European colonists. Understanding how past dynamics have shaped the genetic structure of today’s current population can yield deeper insights into human genetic resilience.”
Academic institutions from around the world were part of this project, which was supported by the GenomeAsia100K consortium, a nonprofit effort to analyze Asian genomes to advance precision medicine and biomedical research.
“Our study shows that a greater diversity of human genomes is found in Asian populations, not European ones, as has long been assumed due to sampling bias in large-scale genome sequencing projects," added penultimate study author Stephan Schuster, an NTU Professor, among other appointments.
Sources: Nanyang Technological University of Singapore (NTU), Science
