Despite having nearly identical DNA sequences, chimps and early humans underwent critical shifts in how DNA is packaged inside their fat cells, Swain-Lenz and her Duke colleagues have found.
As a result, the researchers say, this decreased the human body’s ability to turn “bad” calorie-storing fat into the “good” calorie-burning kind.
While other primates have less than 9% body fat, a healthy range for humans is anywhere from 14% to 31%.
To understand how humans became the fat primate, a team led by Swain-Lenz and Duke biologist Greg Wray compared fat samples from humans, chimps and a more distantly-related monkey species, rhesus macaques.
One of the reasons we’re so fat, the research suggests, is because the regions of the genome that help turn white fat to brown were essentially locked up -- tucked away and closed for business -- in humans but not in chimps.
“We’ve lost some of the ability to shunt fat cells toward beige or brown fat, and we’re stuck down the white fat pathway,” Swain-Lenz said.
Because of brown fat’s calorie-burning abilities, numerous researchers are trying to figure out if boosting our body’s ability to convert white fat to beige or brown fat could make it easier to slim down.