Chimpanzee Sanctuary Northwest

Hope. Love. Home. Sanctuary for primates.

self-medication

Dr. Missy’s Miracle Spring Grass

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The chimps are constantly snacking on grass this time of year. Despite having access to two acres of the stuff, the best grass seems to grow just outside the greenhouse, which means that the humans have to do all the work and the chimps don’t have to get up and walk anywhere.

Convenient, isn’t it?

Missy requested a couple of bunches this afternoon and proceeded to make a nest on the greenhouse platform. This is quite common – when the chimps receive something they know they will enjoy, like when Jamie gets a new book or pair of boots, they often choose to make a nest before settling down with their new treat.

Sometimes the chimps shove handfuls of grass into their mouths all at once, while other times they take a more delicate approach, carefully separating each blade from the stem and eating them one by one.

Using their lips and tongue, they fold the blade up like an accordion and swallow it with minimal chewing.

As we’ve mentioned before on this blog, this is very similar to the way some chimps in the wild ingest certain plants for medicinal purposes.

We do routine checks for parasites so it’s unlikely that they are self-medicating the way wild chimps do. But who knows? Maybe its preventive medicine. Or maybe it’s just a snack. Whatever the reason, the prescription is always the same: More of that grass, please.

Wild food…and medicine?

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The chimps spend a lot of time looking for food on their own this time of year.

Annie:

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They love to eat grass, dandelion leaves, prickly lettuce, mustard, and many other wild plants, as well as the bamboo and fir trees that we have planted.

Negra:

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Sometimes they sit down and eat them outdoors; other times they collect them and return to the greenhouse.

Missy:

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Every once and a while they find something new that we haven’t seen them eat before, or that we didn’t even know was growing on the hill. And when they do, it sends us racing to the computer in a panic to figure out what they’re eating and to make sure it’s safe!

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This morning, while the other chimps were munching on grass, Jody seems to have found herself some wild rose – a new one to us. She’s by far the most adventurous eater of the group and she will go to great lengths to eat small amounts of certain plants.

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Wild chimps are known to self-medicate, a behavior known as zoopharmacognosy. Some swallow Aspilia leaves whole to treat parasites, others eat clay to ease an upset stomach. This type of behavior is most likely culturally acquired, and chimp culture is not something the Seven ever got to experience in the lab. And of course there is almost no overlap between the plants found across equatorial Africa and the plants found on Young’s Hill, so it’s doubtful that they have any type of innate knowledge of which particular plants to eat. But sometimes I’m struck not just by the type of plants they’re eating, but by the way in which they eat them. If you’re hungry and you want to eat grass, you might as well just stuff your face, as Burrito so happily demonstrates here:

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But we occasionally see the chimps carefully swallowing a single blade of grass at a time, even carrying that single blade from the top of the hill back to the greenhouse. And sometimes, instead of chewing the grass first, they fold it up like an accordion and swallow it whole, like wild chimps do with Aspilia.

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Is it possible for captive chimps to learn a basic form of self-medication on their own? The Seven are routinely screened for parasites, so it’s highly unlikely that they are knowingly treating a parasitic infection as their wild counterparts do. But as is the case with so much that fascinates us about chimps, where intelligence, instinct, curiosity, and culture are inextricably interwoven into complex patterns of behavior, it certainly leaves you wondering…