The basic process for developing fingers and toes in land animals may have existed for more than 500 million years in shark genes, according to a new study. Researchers identified genetic activity in spotted catsharks embryos that signal the creation of digits.
The discovery pushes back the date of the evolutionary "fin to limb" advance by some 135 million years. When a gene—essentially a set of instructions—is translated into a trait, such as red hair or an arm, it is said to be expressed. Scientists have long believed that the gene for digit development was first expressed some 365 million years ago in the earliest tetrapodsthe first vertebrates to walk on land.
Kemo D. (a.k.a. no.7) www.beyondgenes.com