A Quechua man overlooks the Andes Mountains.
Galen Rowell / Getty Images
By Freda Kreier
Human evolution is at work in the Andes Mountains. The Quechua, an indigenous people of Peru who have lived at an altitude of more than 2,500 meters for the past 11,000 years, have developed genetic adaptations to survive their harsh environment. A new study finds that these extreme conditions can change chemical modifications that control the activity of that DNA. These “epigenetic” changes are the first evidence that growing up in the mountains can change not only genes, but how the body uses them.
Scientists have long wondered if environmental stresses, such as low oxygen levels, can affect gene activity in highland residents, says Case Western Reserve University anthropologist Cynthia Beall, who studies high-altitude adaptations in Tibet. This “groundbreaking” study shows that not only is it possible, says Bell, who was not involved in the study, but it likely also involves epigenetic changes.
Your environment can cause chemical modifications to your DNA that turn genes on or off, or decrease or increase the activity of certain genes. The strategy allows people to adapt to their environment much faster than pure genetics allows. Still, it’s unclear what role epigenetics plays in helping people adapt to life at a high altitude.
So in the new study, a team of international researchers from Peru, Germany and the United States looked at an epigenetic process called methylation, in which cells add chemical tags called methyl groups to DNA. The team studied three groups: Quechua who were born and raised above 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 sea level before they were born.
The data revealed significant differences in methylation patterns between the groups, the team reported last month Genomic Biology and Evolution. Genes involved in making red blood cells and building endurance muscle were more methylated in Quechua who 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 modifications were likely cemented into Quechua’s DNA because they were exposed to low-oxygen conditions before birth and during childhood.
But other methylated regions, including about one gene involved in sugar breakdown, were exclusive to the high-altitude group born and raised, the team found. This suggests that such changes only occur when Quechua is constantly exposed to high altitude.
The scientists were unable to determine whether any of the epigenetic modifications they saw altered the activity of the genes. But they did find that many of the changes were irreversible, meaning that the methylation of DNA in Quechua moved those to lower altitudes while adults continued to pretend they were at a high altitude.
“I’m excited that we’ve found anything at all,” said lead author Ainash Childebayeva, a postdoctoral researcher at the Max Planck Institute for the Science of Human History. The findings, she says, provide more evidence for the idea that humans can evolve into challenging conditions much faster than previously thought.
Childebayeva hopes her work will inspire others to investigate these questions in people in the highlands around the world. At least a scientist is considering it. The study, Beall says, “makes me want to talk to the person doing my DNA analysis and see if we should look at methylation.”