How is man responsible for there being lesser snakes today
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A green snake
Green snakes have no limbs at all and now scientists know why. SIRIPONG JITCHUM/ISTOCKPHOTO
Tiny DNA tweaks made snakes legless
By Elizabeth PennisiOct. 20, 2016 , 3:30 PM
Sometimes, a genetic tweak can make a really big difference in an animal’s appearance. That’s what likely happened when the predecessors of modern snakes lost their legs, a process that started some 150 million years ago, two separate groups of scientists have discovered. Although the teams took very different approaches to solve the mystery of how those limbs vanished, both came up with similar results: Mutations in DNA located near a gene key to limb formation keep that gene from ever turning on, they report today.
The new studies have impressed other scientists in the field. In both cases, "there is a correlation between the molecular findings on the one hand and the evolutionary trend of limb reduction and loss on the other," says Michael Richardson, a developmental biologist at Leiden University in the Netherlands. The findings show “there can be pretty minor changes in the genome that can account for very big specific changes,” adds James Hanken, an evolutionary developmental biologist at Harvard University.
Though they are reptiles, almost all snakes are completely missing the limbs typical of most land vertebrates. They didn’t start out that way: More than 100 million years ago, snakes had visible legs. And even today pythons and boas have tiny leg bones inside their bodies, suggesting they have vestiges of the molecular pathway for building these appendagesyaa