Ancient viruses responsible for our big brains

Ancient viruses that infected vertebrates hundreds of millions of years ago played a pivotal role in the evolution of our advanced brains and large bodies, a study said Thursday.

The research, published in the journal Cell, examined the origins of myelin, an insulating layer of fatty tissue that forms around nerves and allows electrical impulses to travel faster.

According to the authors, a gene sequence acquired from retroviruses -- viruses that invade their host's DNA -- is crucial for myelin production, and that code is now found in modern mammals, amphibians and fish.

"The thing I find the most remarkable is that all of the diversity of modern vertebrates that we know of, and the size they've achieved: elephants, giraffes, anacondas, bullfrogs, condors wouldn't have happened," senior author and neuroscientist Robin Franklin of Altos Labs-Cambridge Institute of Science told AFP.

Brad Zuchero, a neuroscientist at Stanford University not affiliated with the research, said it "fill(s) in a major piece of the puzzle about how myelin came to be during evolution," calling the paper "exciting and insightful."