I recently ran across a bit of research out of the University of Michigan that I found fascinating. The issue is that it’s a review article of scientific literature rather than an individual study with a specific finding. Not that I have any problems with review articles; they are important pieces of work that bring to light scholarly trends and fit together separate pieces of data. It’s just that their so damned big and comprehensive, which makes it pretty difficult to write a post about a particular finding. So instead, let’s just talk for a second about the overall coolness factor of what the review is about.
Animals medicate themselves.
I don’t know about you, but I had never really thought about this before. But it makes sense. There’s a whole world of pathogens out there that an organism has to protect itself against, and evolving in-body defenses to each and every one of them just isn’t very likely, especially if you can find an outside source for defense. Coevolving with such protections would all but ensure that your species wouldn’t evolve its own immunity.
There are some obvious examples out there, like other primates besides humans seeking out medicinal herbs to treat their diseases. Whether they’re making a conscious, remembered decision or if its pure instinct can probably be debated, but any way you look at it, they’re self-medicating. But outside of these obvious examples, there’s a whole host of awesome symbiosis of plants and animals everywhere in the world.
My favorite example probably comes in the form of honeybees. Because their own immune systems can’t protect them from certain bacteria, they incorporate antimicrobial resins into their nests. Or is it the other way around? Have they not developed certain antibacterial resistance because the resins have always been around to protect their home from infection? Either way, this particular example shows how us humans can go and fuck things up.
Resins aren’t exactly a desirable flavor in honey. It has been a common practice for some time to discourage honeybees from using resin in their nests by selecting for those hives that use less of it. Over time, populations have emerged that don’t have the natural protection from certain bacteria that they need. While that is certainly not the reason for colony collapse disorder and the plummeting honeybee population, I’m sure it doesn’t help, either.
While I’m at it, how about a few more interesting self-medicators? Wood ants also take antimicrobial resins from their trees and incorporate it into their nests. Parasite-infected monarch butterflies protect offspring by laying their eggs on anti-parasitic milkweed. Gypsy moth caterpillars consume foliage high in certain toxic compounds to reduce transmission of deadly viruses. And perhaps weirdest of all, some studies suggest that house sparrows and finches add high-nicotine cigarette butts to their nests to reduce mite infestations.
With how smart birds have been shown to be, I don’t doubt that last one for a second. It’s a pretty cool world out there. As author Mark Hunter, a professor in the department of ecology and evolutionary biology at the University of Michigan, puts it, “When we watch animals foraging for food in nature, we now have to ask, are they visiting the grocery store or are they visiting the pharmacy?” Hunter said. “We can learn a lot about how to treat parasites and disease by watching other animals.”
He even goes as far as to suggest that if we keep our eyes open, we might learn a thing or two about where to look in nature for our own next big medical breakthrough. After all, most of our “synthetic” medications are derived from plants and animals found around the world after pinpointing the chemicals responsible for their natural medicinal properties.
Maybe I should take to coating my kitchen cabinets with tree resin?
The paper, “Self-Medication in Animals,” was published in Science by Hunter, Jacobus de Roode of Emory University, and Thierry Lefevre of the Institut de Recherche pour le Developpement in France.