A Quechua man looks at the Andes mountains.
Galen Rowell / Getty Images
De Freda Kreier
Human evolution works in the Andes mountains. Quechua, an indigenous people of Peru who have lived at altitudes of over 2,500 meters for at least the last 11,000 years, have evolved genetic adaptations to survive their harsh environment. A new study finds that these extreme conditions can change the chemical changes that control the activity of that DNA. These “epigenetic” changes are the first evidence that growing in the mountains can change not only the genes, but the way the body uses them.
Scientists have long wondered whether environmental stress, such as low oxygen levels, can shape gene activity in people in mountain areas, says anthropologist Cynthia Beall of Case Western Reserve University, who is studying adaptations to high altitudes in Tibet. This “pioneering” research shows that not only is it possible, says Bell, who was not involved in the study, but epigenetic changes are likely involved.
Your environment can cause chemical changes in your DNA that activate or deactivate genes or decrease or increase the activity of certain genes. The strategy allows people to adapt to the environment much faster than pure genetics allows. However, it is not clear what role epigenetics plays in helping people adapt to life at high altitudes.
Thus, in the new study, a team of international researchers from Peru, Germany and the United States analyzed an epigenetic process called methylation, in which cells add chemical labels called methyl groups to DNA. The team studied three groups: Quechua who was born and raised over 3,000 meters, Quechua who were born at high altitudes but moved to sea level when they were young, and Quechua whose families moved to the sea before it is born.
The data revealed significant differences in methylation patterns between groups, the team reported last month in Genome biology and evolution. The genes involved in creating red blood cells and building endurance muscle have been further methylated in Quechua, which were born and spent most of their early life at high altitudes, regardless of whether they moved to lower altitudes later in life. These epigenetic changes were probably cemented into Quechua DNA because they were exposed to low oxygen conditions before birth and during childhood.
But other methylated regions, including around a gene involved in the breakdown of sugar, were exclusively the group born and raised at high altitudes, the team found. This suggests that such changes occur only when Quechua is constantly exposed to high altitudes.
Scientists have failed to determine whether any of the epigenetic changes they have seen have altered gene activity. But they found that many of the changes were irreversible, which means DNA methylation in Quechua that moved to lower altitudes as adults continued to act as if they were at high altitudes.
“I think it’s interesting that I found something,” says lead author Ainash Childebayeva, a postdoctoral researcher at the Max Planck Institute for Human History. The findings, she says, provide more evidence that people can evolve to challenging conditions much faster than previously thought.
Childebayeva hopes her work will inspire others to investigate these questions in mountain people around the world. A scientist, at least, has this in mind. The study, says Beall, “makes me want to talk to the person who does my DNA tests and see if we should look at methylation.”