“Sloths are inherently limited by their slow metabolism and unique inability to regulate body temperature effectively, unlike most mammals,” Cliffe explained in an accompanying statement. “Our ...

Ancient sloths lived in trees, on mountains, in deserts, boreal forests and open savannahs. These differences in habitat are primarily what drove the wide difference in size between sloth species.

While humans wouldn’t be very happy to find that organisms were growing on their skin, particularly fungi, algae, and insects, it works out pretty well for sloths. Sloths may be hosting entire ...