Tracing humanity’s longest walk to the southern most tip of South America

Amazing stuff!

"During the late Pleistocene epoch, ancient humans expanded out of Africa, eventually spreading all over the world. Those who reached the southernmost tip of South America completed the longest migration of all—although when exactly they arrived has long been the subject of debate.

Now, using DNA sequence data from 1537 individuals representing 139 ethnic groups, scientists have unlocked some of the mysteries of this historic journey . The new study, led by researchers from the GenomeAsia 100k project, reveals that early Asians traveled more than 20,000 kilometers from North Asia to South America—a trek that would have taken multiple generations. After arriving at the northwestern tip of South America about 14,000 years ago, these early migrants split into four distinct groups: One remained in the Amazon basin, another moved eastward to the dry Chaco region, a third went south to Patagonia, and the fourth to the valleys of the Andes mountains.

The long, arduous migration caused genetic diversity to dwindle. Once the South American groups split up and became geographically isolated, this diversity decreased even more—leading to a marked reduction in variation in human leukocyte antigen (HLA) genes, which play a key role in the immune system. The loss of diversity in these genes could explain why some Indigenous communities were so susceptible to diseases later introduced by European colonists, the researchers say. ..."

From the editor's summary and abstract:

"Editor’s summary

From our origins in Africa, humans have migrated and settled across the world. Perhaps none of these migrations has been the subject of as much debate as the expansion into and throughout the Americas. Gusareva et al. used 1537 whole-genome sequenced samples from 139 populations in South America and Northeast Eurasia to shed light on the population history of Native Americans. Collected as a part of the GenomeAsia 100K consortium, analysis of these data showed that there are four main ancestral lineages that contributed to modern South Americans. These lineages diverged from each other between 10,000 and 14,000 years ago, and this analysis reveals more details of the population history dynamics in these groups. ...

Abstract

Genome sequencing of 1537 individuals from 139 ethnic groups reveals the genetic characteristics of understudied populations in North Asia and South America. Our analysis demonstrates that West Siberian ancestry, represented by the Kets and Nenets, contributed to the genetic ancestry of most Siberian populations. West Beringians, including the Koryaks, Inuit, and Luoravetlans, exhibit genetic adaptation to Arctic climate, including medically relevant variants.

In South America, early migrants split into four groups—Amazonians, Andeans, Chaco Amerindians, and Patagonians—~13,900 years ago.

Their longest migration led to population decline, whereas settlement in South America’s diverse environments caused instant spatial isolation, reducing genetic and immunogenic diversity. These findings highlight how population history and environmental pressures shaped the genetic architecture of human populations across North Asia and South America."

ScienceAdviser

Asians made humanity’s longest prehistoric migration and shaped the genetic landscape in the Americas, finds NTU Singapore-led study

Longest early human migration was from Asia, finds NTU-led study published in Science (original news release, YouTube video)

 

From North Asia to South America: Tracing the longest human migration through genomic sequencing (open access)

Fig. 1. Population structure and admixture.