Our wounds heal slower than cuts and scratches of other primates

Human wounds take almost three times as long to heal as damage from other mammals, included chimpanzees, which are among our closest living relatives. It is not clear why, but it can be an evolutionary adaptation associated with the loss of most of our body hair.

People have snail healing compared to other animals. To see how slow this is, Akiko Matsumoto Oda at the University of the Ryukyus in Japan and her colleagues turnedChlorocebus Pygerhythrus), Sykes’ monkeys (Cercopithecus albogularis), Olive bavians (Papio Anubis) and chimpanzees (Pan Troglodytes).

The researchers, who were stunned at least five of each kind of prime, shaved a small stain of their hair and created a circular wound 40 millimeters across as they treated with an antibiotic ointment and covered with gauze in a day to protect infection.

Photographs and measurements of the wounds taken every few days revealed that they all healed at approx. 0.61 millimeters per Day.

Next, Matsumoto-Oda and her colleagues looked at 24 patients at the University of the Ryukyus Hospital after removing skin tumors, finding that these wounds healed at a speed of only 0.25 millimeters a day.

The researchers also conducted studies of mice and rats and found virtually the same healing speed as in the non-human primates. This suggests that there may be an evolutionary optimal healing speed for most mammals, but not humans, says Matsumoto Oda.

“The most important thing is that we found that chimpanzees showed the same wound-healing speed as other non-human primates, which means that the slowed wound healers seen in human likes probably evolved after the divergence of our common tribal father with chimpanzees,” says Matsumoto-Oda.

Why this happened is not known, but she says it may be attached to how early people adapted to heat around. “The slower wound healing speed of humans may be linked to evolutionary changes, such as reduction in body hair,” says Matsumoto-Oda. “A higher hard density leads to an increase in stem cell numbers, resulting in faster healing.”

Social support, in the form of food sharing, nursing and medicine, may have compensated for the disadvantages of slow healing, she says.