Scientists have revealed the secret of sloths" slowness

Unique "jumping genes" in sloth DNA help these animals conserve energy at the cellular level, which explains their record-slow metabolism and unhurried lifestyle. This is the conclusion reached by scientists from the Wellcome Sanger Institute, who published the results of their work in the journal BMC Biology.

Sloths have long earned their reputation as the slowest mammals on the planet. Their metabolic rate often falls short of even half of what would be expected for animals of comparable size. It is precisely this trait that enables them to hang motionlessly from tree branches for hours and survive on meager, low-calorie food.

To uncover the nature of this phenomenon, an international team of researchers sequenced the genomes of the two-toed sloth and the southern tamandua — its closest relative. Comparative analysis revealed something remarkable: sloth DNA contains special transposons, so-called "jumping genes" — fragments of genetic code capable of moving around the genome and influencing the activity of other genes.

According to the scientists' estimates, these genetic elements appeared in the common ancestor of modern sloths approximately 30 million years ago. A significant portion of them turned out to be associated with mitochondria — the cellular "power plants" responsible for energy production — as well as with key metabolic processes.

The study authors believe that these changes may have played a decisive role in shaping the sloths' unique energy regime. Over millions of years of evolution, the animals developed distinctive genetic mechanisms that allow the body to function fully even at extremely low metabolic rates.

The researchers emphasize that the discovery could prove significant far beyond the field of zoology. Mitochondrial dysfunction is linked to a wide range of human diseases, including diabetes, neurodegenerative disorders, age-related conditions, and muscle atrophy.

In the authors' view, sloths could serve as a natural model for studying how cells cope with acute energy deficiency. In the long term, the findings could prove useful in research on aging, metabolic diseases, regenerative medicine, and even in preparation for long-duration space missions.