The question of when the first snakes were separated from their families — lizards — worried scientists for centuries. The first of its kind study, analyzed the genes of all living families of lizards, found that there were snakes on land, not in the ocean. Nicolas Vidal and Blair Hedges of Pennsylvania State University tested the two theories of the origin of snakes.
They collected the largest database of genetic data for snakes and lizards (including the genomes of 64 species representing all 19 families living in the world of lizards and 17 of the 25 families of modern snakes). In order to confirm the validity of hypotheses about the origin of sea snakes, the scientists had to prove their kinship with a single species of lizards that lived in the sea at a time when there were snakes — the now extinct giant mosazavrami (for lack of their genomes were used genomes of their closest living relatives — for example, from the island of Komodo monitor lizard).
After analyzing the genetic sequence of each species, the researchers used several statistical methods to determine the degree of kinship of animals. After that, Vidal and Hedges were able to build a family tree showing the degree of relatedness of these species. The results showed that mosazavry (only water lizards) were closest relatives snakes. And since all the other lizards at that time lived on land, the study gave a solid reason to believe that the first snake also appeared on land.
The study allowed us to obtain an answer to another long-standing question — why snakes lost their limbs. The reason may be their way of life on land, when they need it from time to time to dig into the soft earth. And with legs can be a serious impediment.
Battery News, 09/02/2004 10:25