Chimpanzees apply insects to their wounds!
When you have a nasty cut, or a graze, you naturally go to treat your wound. Now this might include whacking on some antiseptic or applying an analgesic cream and wrapping it up in a plaster. But one family has recently been found using something of an unconventional approach. Harry Lewis heard all about it from Simone Pika and Lara Southern, who are at the University of Osnabrück...
Lara - In this video, you'll see the mother sit up and reach out to grab a small object from under a leaf, which she then moves to her mouth before moving it to the wounded foot of her son. She repeats these last motions a few times, going from her mouth back to the wound of her son, in essence treating him.
Harry - What is Susie reaching out to grab?
Simone - What we know at the moment is that this is a flying insect. We haven't identified the species yet because if you watch closely at what Susie's doing, she's catching it and putting it into her mouth. There are probably two things she's doing here. First of all, she might be immobilising it, so that the insect is not just flying out of her mouth. But it seems she's also pressing it to press something out of it and then put it into the wound. Sometimes they also take it out of the wound again, put it again in the mouth, squeeze it again, and then reapply it. But this means after an insect application event, there's not much left of these tiny little insects and so far, we haven't been able yet to identify this.
Harry - Okay. And we should probably let everyone in on the secret. Shouldn't we Simone, this is actually a group of chimpanzees, isn't it?
Simone - Oh yeah.
Harry - Oh yeah.
Simone - Yeah. Chimpanzees live in a 'fission-fusion system', meaning they are not always together. We have at the moment, in one of our groups, around 45 individuals with adult males, females, and their offspring. But then during the day, the chimpanzees split up into smaller parties. What you see here is a little party, just Susie with her family, but later in the clip, there's another female and a male joining who want to look at what has happened.
Harry - So we think that it's for a medicinal purpose, but have we seen this elsewhere? Is this completely brand new?
Lara - Actually self-medication is quite widespread across a lot of animal taxa. Even in other subspecies of chimpanzees, they do self-medicate with plants by digesting certain plants and leaves. This is to deal with intestinal parasites, but this is the first time that we've ever seen any kind of topical application of any kind of animal matter to a wound specifically.
Harry - I assume that by putting it to the mouth, either disabling it or squashing it, they're releasing the active ingredient.
Simone - We looked into the literature and actually there's huge literature on substances in insects or the larvae. These substances range from antibacterial, antifungal and antiviral to anti-inflammatory and even just soothing substances. We think that there is really the potential that maybe they go for insects, which have these substances. But to really understand this, we first have to identify the insects and then we have to investigate and analyse the involved substances.
Harry - And I'm assuming as well, Simone, that this isn't something that is just a one off. You've seen this happen more than once. Has it spread outside the troope or is it very much within just this family of chimpanzees?
Simone - During the last 15 months, we’ve recorded 76 different wounds and in 25% of these cases, the chimpanzees caught insects and applied them to the wounds. At the moment we think that this is a phenomenon which the majority of our individuals are using. We saw it in 22 different chimpanzees of our 45 chimpanzees.
Harry - From what we’ve already discussed, I know that you don’t know what the insect is, are there any guesses at this stage?
Simone - We can narrow it down to a flying one. Also, maybe you’ve seen this already. When you have a wound, and there is liquid coming out of it, there are a lot of insects that like to land on the wound. If we speculate a little bit about how such a behavior was invented, it could just be possible that it was one of these flies landing on the wound and wanting to get something from the wound. Then the chimpanzee tried to chase it away but smashed it, it landed in the wound and then there was a direct effect that soothed his pain. That could be a possible scenario but we don’t know. Maybe it’s something different and I hope we find out soon.