Human limbs and shark fins have same genetic source: study

U.S. researchers have discovered a shared gene between sharks and humans that could explain how both arms and fins evolved.

Scientists from the University of Florida observed about a dozen genes in a spotted cat shark's median fin.

The results showed that these genes were the same ones vital to the development of human arms and legs.

To learn more about the origins of limbs in both species, the scientists put molecular markers on different cell types in the shark to determine which gave rise to its median fin.

The study showed that the cells located in the median fin were the ones that also dictated the positioning of its side fins.

Based on these findings, the scientists concluded that the midline - which contains the dorsal, tail, and anal fins of a fish - is where the genetic template for limb positioning originated.

The researchers suggested that the template may have dated back to prehistoric times, about 100 million years before fins developed.

The scientists also claimed that the genetic template could explain human birth defects.

The researchers' study is published in the July 27 issue of Nature.

Photography: World Shark

Source: Discovery Channel Reports, July 27 edition