A Chimp's Gray Hair Doesn't Have Much to Do With Age

The first time Jane Goodall met the ape who would change the world was back in 1960. He was using a grass stalk to pry loose termites from a mound in Tanzania’s Gombe National Park.

Later, the naturalist watched him wield a fishing rod, crafted from a carefully sculpted twig, to gather up his favorite dish. When she befriended the chimpanzee, he opened up the world of Gombe park’s chimpanzees to her — a world that Goodall, in turn, would famously share with the rest of us. He made introductions, kept the peace, and held a hand or two when someone needed comfort.

“At this intimate range, I observed details of their lives never recorded before,” Goodall would later recall in National Geographic. “Most astonishing of all, I saw chimpanzees fashion and use crude implements — the beginnings of tool use.”

In fact, the chimp revealed so many qualities once thought exclusive to humans, she gave him a very human name: David Greybeard.

But there was one quality that David and his kind never shared with their more upright-walking counterparts. That gray-flecked beard may have given him a certain air of refinement and maturity, but it probably had nothing to do with his age. In fact, Goodall surmised that he was in the prime of life.

Unlike in humans, gray hair isn’t much an indicator of an ape’s age. At least those are the findings of a 2020 study in the journal PLOS ONE. The research suggests that unlike humans, chimpanzees don’t lose pigmentation as they age. There’s no dignified transition from pepper to salt and pepper to strictly salt.

Instead, hair goes gray roughly until an ape reaches midlife. Then it holds steady at salt and pepper regardless of age.

“With humans, the pattern is pretty linear, and it's progressive. You gray more as you age. With chimps that's really not the pattern we found at all,” the study’s lead author Elizabeth Tapanes, a Ph.D. candidate at George Washington University, explains in a press release. 

“Chimps reach this point where they're just a little salt and peppery, but they're never fully gray so you can't use it as a marker to age them.”

To determine how aging and graying are connected for chimps, the researchers studied photos of the animals — both in the captivity and the wild. They literally counted gray hairs. Then they compared that gray-hair rating with the individual ape’s age. They didn’t find a correlation. Just a steady growth of gray for the animals’ first few years — and a plateau.

Chimps, it seems, don’t fully commit to salt or pepper.

But researchers aren’t sure yet what function that may serve. In humans, there are all sorts of reasons why hair goes gray, with biological age being foremost among them.

Chimps, on the other hand, don’t offer that marker. Researchers suggest they may hold onto dark hairs to help regulate their body heat — something that may be vital when wearing a fur coat in the jungle. The patterns may also simply help chimps identify one another.

After all, that’s how Jane Goodall identified her first friend at Gombe Park, the wise and mature — but not necessarily old — David Greybeard.