The self-medication of animals isn’t a new phenomenon. We’ve long known, for example, that birds, bees, lizards, frogs, and hedgehogs all do it, using foodstuffs or extracts of plants, say, to kill off parasites, bacteria, or viruses. Although the tale of elephants using certain fruits to get drunk is, sadly, a myth, chimpanzees in Guinea have been spotted “self-medicating” using naturally fermented palm wine.
That doesn’t mean that it’s not fascinating when a new example of self-medication in the wild is spotted, though, with Eulemur rufifrons – Madagascar's red-fronted lemur – being the latest addition to this collection. As reported by a study led by Germany’s Leibniz Institute for Primate Research, they appear to use millipedes to treat or prevent itching and weight loss triggered by pesky gut parasites.
Although it cannot be directly confirmed that this is what the millipedes are chewed on for, there’s some decent observational evidence to suggest that’s the case. Explaining their hypothesis in the journal Primates, the team note that the millipedes aren’t necessarily eaten, just mechanically crushed in order to get to the bodily fluids within.
At this point, the six wild lemurs – both male and female – anointed their near-anal and genital areas, along with their tails, with the squashed millipedes. The researchers suspect that the benzoquinone compounds within the millipedes are designed to deter nematode worms of the family Oxyuridae, which are literally a pain in the ass.
Infestation of these worms, along with the implantation of their eggs, is not an uncommon occurrence in lemurs. As well as robbing them of vital nutrients, they can induce extremely itchy rashes. Indeed, the team spotted several red-hued bald spots on the lemurs, including around their nether-regions, perhaps marking infestation sites.
Benzoquinone compounds are already known to repel mosquitos, and it’s likely that the substance not only deters infection by these nematode parasites, but also prevents the condition. These particular lemurs probably stumbled upon the curative after trying many substances down below, in a trial-and-error approach – although plenty of millipede species are known to contain repellant substances.
Self-anointing is a common behavior in self-medicating animals. The decidedly very clever capuchin monkey – already highly adept at using several stone tools to source food – is known to use mixtures of millipedes, ants, limes, and onions for parasite-repelling reasons. Spider monkeys, on the other hand, appear to self-anoint with certain plant species in order to scent up and woo a mate.
The team’s hypothesis is certainly reasonable, then, but in order to corroborate their ideas, more work is required. At present, it’s unclear if there is any difference between parasite-infested lemurs that self-anoint and eat the millipedes and those that don’t ingest them.
Either way, there’s a good chance that these lemurs are entry-level pharmacologists.