Ancient Viruses Shaped Human Bodies: Study

A groundbreaking study suggests that an ancient virus infection in vertebrates millions of years ago significantly contributed to the development of complex brains and large body sizes in humans. Published in the journal Cell, the research highlights the critical role of myelin, a fatty insulating layer around nerves enhancing the speed of electrical impulses, in this evolutionary advancement.

The study reveals that a gene sequence borrowed from retroviruses, which integrate into their host’s DNA, is crucial for myelin production. This genetic code is found in contemporary mammals, amphibians, and fish, indicating its widespread impact across vertebrates.

Robin Franklin, a senior author and neuroscientist at Altos Labs-Cambridge Institute of Science, expressed to AFP his amazement at how this viral integration facilitated the diverse and large sizes of modern vertebrates, ranging from elephants to condors.

Led by Tanay Ghosh, a computational biologist and geneticist in Franklin’s team, the research delved into genome databases to identify genes likely involved in myelin production. Ghosh focused on the so-called “noncoding regions” of the genome, previously considered nonfunctional “junk,” now recognized for their evolutionary significance.

Ghosh’s investigation uncovered a sequence originating from an endogenous retrovirus named “RetroMyelin,” which has been part of our genetic makeup for a long time. This sequence, found in jawed vertebrates including mammals, birds, reptiles, amphibians, and fish—but absent in invertebrates and jawless vertebrates—emerged around the same time as jaws, about 360 million years ago during the Devonian period, also known as the Age of Fishes.

The study suggests that the evolutionary advantage of quicker nerve impulse transmission, facilitated by myelin, played a crucial role in the survival strategies of both predators and prey. Myelin’s ability to conduct impulses rapidly without increasing nerve cell diameter allows for denser nerve packing and supports longer nerve growth, ultimately contributing to the development of longer limbs and larger body sizes.