Humans Still Evolving Right: Genes Reflect Diet and Altitude
Human evolution is still visible in traits linked to diet, altitude and sunlight, research shows. Examples include lactose tolerance, starch digestion among Indigenous Andean people and blood adaptations in high-altitude communities, while scientists also point to changes in skin pigmentation and other features.
Human evolution is still shaping bodies around the world, with signs in traits linked to diet, altitude and sunlight. Research points to lactose tolerance, starch digestion among Indigenous Andean people and blood traits in high-altitude communities as examples of natural selection.
Some of the clearest changes concern what people can digest. In parts of the world, gene variants that allow adults to consume dairy spread after people began keeping cattle and other grazing animals and drinking their milk.
Today, about 30 to 35 percent of adults worldwide can tolerate lactose, according to the research described by evolutionary scientists.
In the Andes, the potato appears to have influenced another digestive adaptation. The Quechua people of highland Indigenous Andean ancestry were among the first groups to domesticate the crop.
Earlier this year, researchers found that this population appears better equipped to digest starch than almost any other group. Evolutionary anthropologist Omer Gokcumen of the University at Buffalo said, “Biologists have long suspected that different groups of humans have evolved genetic adaptations in response to their diets.”
“But there are very few cases where the evidence is this strong,” Gokcumen said.
Researchers linked the adaptation to higher copy numbers of a gene variant. Beginning around 10,000 years ago, people with roughly 10 copies or more had a 1.24 percent survival or reproductive advantage per generation.
“Those with lower copy numbers were eliminated from the population over time, perhaps because they had less number of offspring, and the ones with the higher copy numbers remained,” Gokcumen said.
High-altitude living has also shaped human physiology. Communities on the Tibetan plateau have lived at altitude for more than 10,000 years, and research has identified traits that help blood deliver oxygen.
In 2024, anthropologist Cynthia Beall of Case Western Reserve University and her team reported evidence of those adaptations in Tibetan communities. “This is a case of ongoing natural selection,” Beall said.
A study of 417 Nepalese women who had lived their entire lives above 3,500 meters found that those with the highest rate of live births had red blood cells with unusually high oxygen saturation.
“We knew that higher oxygen saturation of hemoglobin was beneficial; now we understand that the higher the saturation, the more beneficial,” Beall said. “The number of live births quantifies the benefits.”
Skin pigmentation offers another visible example of adaptation. Darker skin among early humans in Africa is widely understood to have helped protect against DNA damage from strong ultraviolet radiation, while selective pressures farther from the equator appear to favor lighter skin.
