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No Private Parts? Chimpanzees Groom Each Other Without Shame

Anywhere and everywhere, chimps help clean each other’s bodies.

Key points

  • Humans consider some body parts “private,” even when they need help with them.
  • Chimps aren’t self-conscious about others touching their face or genitals.
  • Chimps’ unabashed exploration of each other’s bodies provides social and health-related benefits.

The mango fly lays her eggs in your damp clothing. When they touch your skin they burrow in, and gestate into worms below the surface, swelling into infected lumps. Unchecked, they’ll grow for 2-3 weeks, bursting out when they’re ready.

Of course, don’t leave them unchecked. We seal off the breathing hole on Day 3 with clear nail polish then, armed with needles and tweezers, pull them out the next day. For those we can’t reach in the privacy of our own tents, we enlist each other. The back of my shoulder bears the scar from R’s generous handiwork, and B’s bicep bears the scar from mine.

Ticks and ants, we remove from our own bodies, too. We inspect rashes from caterpillar and nettle, punctures from thorn and thistle, stings from bees, all of which hurt and might become infected. We probe them gingerly, douse them in soap, peroxide, and zinc, cover them with small bandages.

A big concern is that the mango fly egg will lodge itself somewhere that you can’t reach yourself but that you don’t want anyone else to reach either. The chance is slim, because those private areas are small, but the fear is real. Chimps have no “private.”

ThomasDeco/Shutterstock
Source: ThomasDeco/Shutterstock

Chimpanzees Without Shame

I recently watched the chimpanzees Wes and Richmond, friends for over 25 years, groom each other’s testicles for a half hour. Not casually, but rather with great concentration, peering close and using all hands available. Richmond lay on his back at one point with his thighs wide to give Wes better access. Then Wes, who is 10 years younger, held Richmond’s chin between thumb and pointer and delicately cleaned Richmond’s eyes with the fingers of his other hand, their faces inches apart as they gazed at each other.

I watched Jolie groom her teenage son’s testicles for a while, and he then groomed her thigh. Jolie’s young daughter draped one of her arms over a branch, so that she wouldn’t have to support her own weight while Jolie cleaned her armpit, and then patiently endured Jolie’s hand clamped over her face and chin while she got her ear canals cleaned. Ten-year-old Salonen carefully searched between his mother Sarah’s legs with his fingers. He really pulled apart crevices, both anal and vaginal, and poked around in there, while Sarah lazily shredded a blade of grass.

Why and Where Chimps Groom

Chimpanzees spend an enormous amount of their time grooming each other. The health-related focus seems to be finding and removing insects and parasites, or scabs. But it serves vital social functions, and varies depending on status—high-ranking chimps are on the receiving end more often, and males who groom females more get more mating access. Grooming is fascinating for many reasons, and great research has been done on it (this and this, for example). But their total lack of body consciousness during grooming is interesting in itself.

The most careful grooming seems to be of the face, ears, and genitals, the very parts we humans are most sensitive about other people touching. Maybe these are the most hairless, so most prone to bugs and ticks, or just the most visible (for the same reason), or the most sensitive, so even tiny things are bothersome. They don’t often do inside each other’s mouths, a location both sensitive and hairless, but likely much less bug-ridden.

Wound care, while commonly done for chimps' own wounds, is curiously uncommon for others’ wounds. Grooming is not the same as cleaning. Dirt is often left alone, as is benign debris (leaves, burrs, etc). It’s not at all clear to a human observer what exactly they’re accomplishing in most cases, the offending tick or dead skin flake being invisible to watchers, though not a shared aesthetic, in any case.

Anything Goes

Chimp grooming is a symphony that can be heard even when we can’t see them, in deep vegetation. Lip smacking, raspberries, teeth clacking, a puh-puh-puh made by popping the lips apart. A sudden delighted mouth sound and a quick scoot forward when they’ve found something of interest makes us human witnesses chuckle to ourselves. No playing it cool, no matter how old the chimps are—finding a tiny speck is just so satisfying, for reasons mysteriously different than ours. Any visible body area, from leg to labia, is fair game. If a chimp is audibly gassy while another grooms them with their mouth, that’s OK too.

High-ranking males can expect substantial anti-parasite benefits by being groomed often and thoroughly—this may help offset the damaging effects of high testosterone on their immune systems. But middle- and low-ranking chimps get groomed too, and groom enthusiastically those both below and above them in the hierarchy, for many hours of the day. Close inspection of a passing friend’s anus, or inside the nose of someone else’s child, is done as casually as sipping water from a puddle.

Touch, Unselfconsciously

I recently winced while a woman at the beach carefully peeled skin off her boyfriend’s sunburnt back. I saw a father kissing the bottom of his infant’s foot, and realized again how much we love touch with those very, very few we share it with.

Clothes (thankfully) make most of our bodies private to the public, and thousands of little plastic tools help us groom ourselves. But for those without clothes or tools handy—sunbathers, babies, massage enthusiasts, and chimpanzees—what joy and relief it can be to touch so unselfconsciously.

References

Muehlenbien, M. & Watts, D. (2010). The costs of dominance: testosterone, cortisol

and intestinal parasites in wild male chimpanzees. BioPsychoSocial Medicine, 4(21).

Clark, I., Sandel, A., Reddy, R., & Langergraber, K. (2021). A preliminary analysis of wound care and other-regarding behavior in wild chimpanzees at Ngogo, Kibale National Park, Uganda. Primates, 62, 697-702.

McGrew, W. & Tutin, C. (1978). Evidence for a social custom in wild chimpanzees. Man, 13(2), 234-251.

Nishida, T., Mitani, J., & Watts, D. (2004). Variable grooming behaviours in wild chimpanzees. Folia Primatologica, 75(1), 31-36.

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