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Jovialis
18-10-18, 18:43
Ancient populations in the Andes of Peru adapted to their high-altitude environment and the introduction of agriculture in ways distinct from other global populations that faced similar circumstances, according to findings presented at the American Society of Human Genetics (ASHG) 2018 Annual Meeting in San Diego, Calif.

John Lindo, PhD, JD, assistant professor of anthropology at Emory University, and a group of international collaborators headed by Anna Di Rienzo, PhD, at the University of Chicago and Mark Aldenderfer, PhD, at the University of California, Merced, set out to use newly available samples of 7,000-year-old DNA from seven whole genomes to study how ancient people in the Andes adapted to their environment. They compared these genomes with 64 modern-day genomes from both highland Andean populations and lowland populations in Chile, in order to identify the genetic adaptations that took place before the arrival of Europeans in the 1500s.

"Contact with Europeans had a devastating impact on South American populations, such as the introduction of disease, war, and social disruption," explained Dr. Lindo. "By focusing on the period before that, we were able to distinguish environmental adaptations from adaptations that stemmed from historical events."

They found that Andean populations' genomes adapted to the introduction of agriculture and resulting increase in starch consumption differently from other populations. For example, the genomes of European farming populations show an increased number of copies of the gene coding for amylase, an enzyme in saliva that helps break down starch. While Andeans also followed a high-starch diet after they started to farm, their genomes did not have additional copies of the amylase gene, prompting questions about how they may have adapted to this change.

Similarly, Tibetan genomes, which have been studied extensively for their adaptations to high altitude, show many genetic changes related to the hypoxia response -- how the body responds to low levels of oxygen. The Andean genomes did not show such changes, suggesting that this group adapted to high altitude in another way.

The researchers also found that after contact with Europeans, highland Andeans experienced an effective population reduction of 27 percent, far below the estimated 96 percent experienced by lowland populations. Previous archaeological findings showed some uncertainty to this point, and the genetic results suggested that by living in a harsher environment, highland populations may have been somewhat buffered from the reach and resulting effects of European contact. The findings also showed some selection for immune-related genes after the arrival of Europeans, suggesting that Andeans who survived were better able to respond to newly introduced diseases like smallpox.

Building on these findings, Dr. Lindo and his colleagues are currently exploring a new set of ancient DNA samples from the Incan capital Cusco, as well as a nearby lowland group. They are also interested in gene flow and genetic exchange resulting from the wide-ranging trade routes of ancient Andeans.
"Our findings thus far are a great start to an interesting body of research," said Dr. Lindo. "We would like to see future studies involving larger numbers of genomes in order to achieve a better resolution of genetic adaptations throughout history," he said.

https://www.sciencedaily.com/releases/2018/10/181017211657.htm

Ygorcs
19-10-18, 00:14
Similarly, Tibetan genomes, which have been studied extensively for their adaptations to high altitude, show many genetic changes related to the hypoxia response -- how the body responds to low levels of oxygen. The Andean genomes did not show such changes, suggesting that this group adapted to high altitude in another way.

I wonder if early and widespread consumption of coca leaves (used as chewing gum or even tea) was in some way a smart discovery by the Andean peoples to help them get adapted to their high altitude environment even in the absence of the genetic advantages provided by random mutations that had the chance to expand in other places, like Tibet. Coca (the plant, not the drug, please! lol) is known to ease the ills caused by the effects of low oxygen in high altitudes and to placate even the pain of hunger.

Ygorcs
19-10-18, 00:22
The researchers also found that after contact with Europeans, highland Andeans experienced an effective population reduction of 27 percent, far below the estimated 96 percent experienced by lowland populations. Previous archaeological findings showed some uncertainty to this point, and the genetic results suggested that by living in a harsher environment, highland populations may have been somewhat buffered from the reach and resulting effects of European contact. The findings also showed some selection for immune-related genes after the arrival of Europeans, suggesting that Andeans who survived were better able to respond to newly introduced diseases like smallpox.


Wow, really?! I don't know the methodological soundness and scientific reliability of using these genetic data to estimate the reduction in population size, but I find a decrease of only 27% very hard to accept in light of what the historic documents say and the archaeological evidences attest (high concentration of settlements and very intensive use of land for agriculture and pasture in the Andes). Most of the Andes is nowadays only relatively populated whereas it was far more populated than the rest of South America in Pre-Columbian times. Okay, it certainly received far fewer immigrants than other regions of the continent, but I'd expect it to be more populated if the reduction from its pre-Columbina population level had been as low as 27%, while that of the lowlands as high as 96%.

Jovialis
19-10-18, 15:10
I wonder if early and widespread consumption of coca leaves (used as chewing gum or even tea) was in some way a smart discovery by the Andean peoples to help them get adapted to their high altitude environment even in the absence of the genetic advantages provided by random mutations that had the chance to expand in other places, like Tibet. Coca (the plant, not the drug, please! lol) is known to ease the ills caused by the effects of low oxygen in high altitudes and to placate even the pain of hunger.

I've heard the same thing in regards to those effects as well.

berun
19-10-18, 17:10
the plant grows in the Amazon bassin, I don't know if it must be chewed fresh to get the boosting effects, but even with a large scale trade it would arrive dry in the Andean plateaus.

Ygorcs
21-10-18, 09:41
the plant grows in the Amazon bassin, I don't know if it must be chewed fresh to get the boosting effects, but even with a large scale trade it would arrive dry in the Andean plateaus.

I think its use and planting must've spread from a pretty early period. There is evidence of coca leaves and chewing in 3,000-year-old mummies and in even older archaeological remains, and not just in the Amazon Basin, but actually even more along the mostly pretty arid Peruvian coast and the Eastern Andes. And by the time of the Inca Empire it was very prized and consumed in all of the mountainous Andes.