Our Wounds Heal More Slowly than Those of Other Primates

Human wounds take nearly three times longer to heal compared to those of other mammals, including chimpanzees, our closest living relatives. While the exact reason remains unclear, it may relate to an evolutionary adaptation linked to body hair reduction.

Human healing is slower in comparison to other animals. To investigate this, Matsumoto Akira, Oda from the University of Lycys in Japan, along with her colleagues, studied four other primate species: Chlorocebus pygerythrus, Sykes’ monkey (Cercopithecus albogularis), olive baboon (Papio anubis), and chimpanzees (Pantroglodytes).

The researchers anesthetized at least five individuals from each primate species, shaving a small patch of hair to create a 40 mm circular wound.

Photographs and wound measurements taken every few days showed that the healing rate averaged about 0.61 mm per day across all species.

Subsequently, Matsumoto-Oda and her team observed 24 patients at Lukyus University Hospital following skin tumor excisions.

The researchers also conducted studies on mice and rats, finding similar healing rates as those of non-human primates. This suggests that many mammals may have an evolutionary optimal healing rate, according to Matsumoto-Da.

“Crucially, we found that chimpanzees displayed the same wound healing rate as other non-human primates, indicating that the slow healing seen in humans likely evolved after our divergence from a common ancestor with chimpanzees,” she noted.

While the exact cause remains unknown, Matsumoto speculates it may relate to how humans adapted to hot environments. “The slower healing in humans might be connected to evolutionary changes, such as hair loss,” she explains. “Denser hair could correlate with higher stem cell counts, leading to faster healing.”

She also notes that social support — through food sharing, nursing, and medicinal care — may have compensated for the disadvantages of slower healing times.