Study reveals how snakes lost their legs

Before snakes slithered on the ground, they used to roam the Earth on legs about 150 million years ago.

But how did they lose their legs?

Scientists from the University of Florida discovered that the genetic process for leg development has "simply switched off" in these reptiles, NPR reports.

The DNA to develop limbs, called the "Sonic hedgehog genome", was discovered in python embryos less than 24 hours old, but shortly fizzled out.

Co-author of the study, Martin Cohn, told NPR that the reason for this genome to switch off is because it does not have 'enhancers' , or DNA sequences, to properly create limbs in a snake embryo.

Several of these enhancers in the Sonic hedgehog genome were deleted at some point during the snake's evolution and caused a mutation, according to Cohn.

But further in the study, Cohn discovered that another gene which makes fingers and toes was active in a python embryo---only that the embryos made a "pre-cartilaginous model of all skeletal elements of the limb," Cohn said to NPD.

"It was absolutely mind-blowing because this was like development of a cryptic leg skeleton in an embryo," Cohn said to NPR.

This finding could be the answer to how snakes evolved to lose their legs.

"There are a number of fossil snakes with legs. Paleontologists have argued that some of these ancient snakes retained the legs of their ancestors, whereas others species evolved after legs were lost, and, thus, they may have reacquired legs." Cohn said to NPR.

Read full story at npr.org 

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