One of the largest studies of populations traditionally ignored by genetics provides this Thursday new details on the longest human migration: from Asia to the southern end of America. There, in Tierra del Fuego, Chile, the Kawésqar continue to live, descendants of the humans who have traveled the further from the original continent of all humans, Africa. The new study warns that the four large native groups in South America have suffered a population decline of up to 80% in the last 10,000 years.
The new data is the result of the Genome Asia 100K consortium, led by the Nanyang Technological University, in Singapore, and overturned to sequence up to 100,000 groups of groups that are not represented in the great studies of this type. Researchers have read the full genome of more than 1,500 people from 139 ethnic groups in Asia and America. The results are published today in Sciencereferent of the best world science.
Researchers have failed to identify the Asian group from which all Native Americans descend. This is because once the first humans reached northern America, there were migrations from American Indians back to Siberia by the Bering Strait, who crossed again with the Inuit and other natives of this region, drunk the original genetic profile. These crosses covered millennia, for 5,000 years, until just 700 years ago, the work reveals. In any case, the analysis shows that the Inuits and other current peoples living in the Eastern East of Russia remain the most related to all American natives. The separation between these two lineages happened between 27,000 and 19,000 years ago.
The study shows that the populations of North and South America separated between 17,500 and 14,600 years ago. Shortly after, between 14,000 and 10,000 years ago, the four large native lineages of South America emerged: the Andean who occupied the high areas along the mountain range, which settled in the dry plains of the Chaco – parties of Brazil, Argentina, Bolivia and Paraguay – the Amazonians who inhabited the jungles, and the Patagonians, which reached the Austral tip of the continent. These groups suffered the consequences of geographical and genetic isolation. The orography itself contributed, because it seems that the Panama isthmus prevented return trips, which would have increased the genetic variety.
The four groups have experienced population declines close to 49% between the Andean and the inhabitants of the Chaco, of 60% among the Amazonians, and of 80% among the Patagonians such as the Kawésqar, who are “on the verge of extinction”, the study warns, next to their language. The genetics of the four groups shows genetic diversity as poor as that of the natives of Andaman, which have lived for centuries in remote islands of the Indian Ocean.
In spite of everything, these peoples managed to survive for 13 millennia, even when the arrival of the European conquerors decimated the populations, especially for imported pathogens. The current descendants of these populations continue to have less genetic variety, including that related to immunity, which makes them more vulnerable to new infectious agents, says Elena Gusareva, the first signer of the study. “Our analysis highlights the profound connection between the environment and the human genome throughout history. As people adapted to diverse environments and, often, extremes – as great altitudes or cold climates – their genomes evolved accordingly. However, with the rapid ongoing climate change, these adaptations could become incompatible with the new conditions, which could potentially generate future health challenges for these Populations, ”reasons in an email.
Genetic variants have also been identified that promote adverse effects of some drugs, as well as beneficial adaptations, such as a better metabolism to survive in icy climates and an adaptation to the scarcity of oxygen possessing the Andean, and that is different than that of the inhabitants of the Himalayan mountain range.
A second study published Thursday in the same magazine analyzes the genome of 2,700 Brazilians and concludes that this is one of the most diverse genetically diverse countries, thanks to its history. After the arrival of Europeans in the 16th century, the country lived one of the greatest known human displacements, with the settlement of about five million European settlers, and at least five million African slaves, in a country where there were already more than 10 million natives who spoke a set of 1,000 native languages. The study verifies that in past centuries the crosses between European men, the settlers, with African or American women, probably subjected, predominated. This pattern has changed, and current couples are much more diverse, although genetic marks of centuries of colonization and slavery are still present.
Almost nine million completely new genetic variants have been discovered for science. Some of them may have important implications for global health, as they are related to greater fertility, metabolism and immune system. In addition, more than 35,000 mutations from African natives and Americans have been detected that may be related to several diseases.
A third study focuses on the extinction of the American megafauna – giant, mastodon, saber teeth …— about 10,000 years ago. This disaster could affect many American native communities that lived from hunting. The wild horses also disappeared at this time, and did not return to America until the Europeans reintroduced them. The work has analyzed almost 70 genomes extracted from wild horse fossils between 50,000 and 13,000 years ago. The results confirm a constant genetic exchange between animals from Eurasia to America and vice versa. There are animal fossils found in Europe that show their kinship with the Americans, including specimens of the Iberian Peninsula. This healthy exchange ended when the Bering Strait Ice Bridge disappeared, and wild horses were extinguished in America. Research, which aims to combine Western science with the knowledge of native communities, has been directed by Ivette Runner horse Collin, researcher at the University of Toulouse (France), and India Oglala Lakota.
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