It Might Be Time to Harvest Sloth Hair for New Medicine

With the exception of the house cat and maybe the honey badger, is there any animal that has risen in acclaim via the internet more than the humble sloth? And why not, right? They seem to have beatific smiles on their faces, as if they know something the rest of us don’t. Rolling stones might no moss, but the world’s slowest mammal sure does, to the point where a sloth can look downright moldy.

The long, thick, coarse outer-hairs of a sloth have long transverse cracks where algae gather and flourish. The algae are species specific and passed down from mother sloth to their absurdly cute offspring, and forms a symbiotic relationship with the mammal—the algae give the sloth camouflage and nutrients in exchange for water and a place to grow. It has also been suggested that the algae encourage the growth of bacteria that is helpful to the sloth, in addition to the cyanobacteria, roundworms, and moth larvae that live in the tiny ecosystem that sprouts while sloths hang from trees.

Researchers who took a long hard look at what’s populating sloths in Panama have discovered that, among the flora and fauna of sloth hair, there are fungi growing that are resistant to the parasites that cause malaria, human breast cancer cell lines, and a range of pathogenic bacteria. Their results have been published in the journal PLOS One.

A team from Panama and the United States took single samples of coarse outer hair from the lower backs of nine sloths living in Soberanía National Park, near the Panama Canal, in February 2011. The hairs were cut up and put into cultures, where the fungi could grow for a few weeks and then be closely examined.

The results were 84 different fungal isolates, some of which, the researchers believe, had never been seen before. Using ethyl acetate to make extracts from the fungi, the researchers found two extracts that inhibited the growth of one of the parasites that causes malaria in humans, eight that inhibit the trypanosoma that causes Chagas disease, and 15 that were highly active against the MCF-7 breast cancer cell line.

The researchers haven’t yet looked at whether these fungi have any influence on the health of the sloths, but they do express belief that future medicine for us humans will come from bioactive microbes, a massive field of research that we’re only beginning to understand. “Conservative estimates suggest that the total number of fungal species in existence exceeds 5 million, yet fewer than 100,000 fungal species have been described,” the paper states.

They ended up poking around on sloth backs because, “abundant evidence points to novel environments as promising sources of as yet undescribed microorganisms,” which definitely seems to be the case with this environment. This research, which indicates that sloths may be growing future anti-malarial, anti-bacterial and anti-cancer drugs right on their backs is one of the more bizarre and exciting chapters in the ever-expanding annals of lore on one nature’s most bizarre and sedentary creatures.