What happened
People take two to three times as long to heal from wounds as other mammals, a team of biologists reported yesterday in the journal Proceedings of the Royal Society B. The researchers suggested the slower healing may have been an evolutionary trade-off when we shed fur for sweat glands.
Who said what
Watching wild baboons fight in Kenya, "I was struck by how frequently they sustained injuries," lead study researcher Akiko Matsumoto-Oda of Japan's University of the Ryukyus told The New York Times, "and, even more, by how rapidly they recovered — even from seemingly severe wounds." Her team's research found that chimpanzees, baboons, monkeys, mice and rats all healed at roughly the same rate, more than twice as quickly as humans.
"Most importantly," the fast healing of chimpanzees "implies that the slowed wound-healing seen in humans likely evolved after the divergence from our common ancestor with chimpanzees," Matsumoto-Oda told New Scientist. Hair follicles contain stem cells that can repair torn skin, and unlike most mammals, "human skin has very puny hair follicles" but ample sweat glands, Elaine Fuchs, a stem cell biologist at the Rockefeller University who was not involved in the study, told the Times.
What next?
"We evolved to cool by sweating profusely," allowing physical activity in the heat and cooling our large brains, Harvard evolutionary biologist Daniel Lieberman told the Times. "The evolutionary disadvantage is that wound healing is slowed," Fuchs said, but unlike other mammals, humans "can put on a coat if they need to." | 
