Ancient Ancestors of Deadly Snakes Swam to Australia, Study Finds

The ancestors of some of Australia's most deadly snakes may have arrived on the continent by swimming there, a study has said.

The paper, published in the journal Genes, examined the origins of two highly venomous Australian snakes—the tiger snake and eastern brown snake—that belong to the elapid family of front-fanged snakes.

Australia is home to a large variety of animals that are not found in any other parts of the world, with many native species arising after the landmass broke off from Antarctica and became isolated tens of millions of years ago.

The paper showed that this geographical isolation might not have prevented the arrival of species like snakes or their ancestors to the continent, however.

The researchers, from Australia and the U.K., compared the genomes of the Australian elapids with several sea and amphibious snakes found in Asia, whose evolutionary paths branched off around 30 million years ago.

By studying the genomes of these snakes, the authors found that their ancestors gained certain mutating genes known as "jumping" genes not found in their land-based cousins.

The findings provided the first evidence that land-based Australian elapids like the tiger and eastern brown snakes came from marine or amphibious animals. The method in studying "jumping" genes was also the first time such genes had been used to confirm the evolutionary course of a species, researchers said.

"[The] marine environment transferred the new genetic material into the snakes and offers new support to the argument that the first Australian elapids swam to our shores," study author David Adelson, of the University of Adelaide's School of Biological Sciences, said in a statement. "They must have previously acquired the new genetic material during an ancestral period when they were adapted to marine life."

Eastern brown snakes and tiger snakes are among the most venomous snakes in the world.

Eastern brown snakes are considered the most-deadly snake in Australia. Twenty three of the 35 deaths attributed to snakes in the country between 2000 and 2016 were caused by brown snakes, one study published in the journal Toxicon found, with cardiac arrests often occurring after the victims were bitten.

The scientists behind the latest paper said their work unambiguously determined the genetic differences between land snakes sea snakes and amphibious snakes. "This is the first time that jumping genes have been used to confirm the evolutionary history of any animal species, and this research definitively proved that the common ancestor of all Australian elapids adapted to a marine environment," Adelson said.

Stock image of an eastern brown snake
Stock image of an eastern brown snake. The animals were responsible for twenty three of 35 deaths attributed to snake bites in Australia between 2000 and 2016. gorgar64/Getty Images