Fascinating finding. "Human and cuttlefish limbs develop under the direction of the same genes"
. To find out more on how our limbs develop and our genetic connections to other animals, definitely read (or watch the documentary) Our Inner Fish
by Neil Shubin.
The cuttlefish and its relatives, squid and octopuses, often strike human observers as floating aliens wreathed in sucker-covered limbs — boneless, squirming appendages that would seem to have nothing in common with our own arms and legs.
But hidden under the superficial differences, a new study shows, are some profound similarities: Human and cuttlefish limbs develop under the direction of the same genes. The new study, published on Tuesday in the journal eLife, lends weight to the theory that many animal appendages, from insect wings to fish fins, share a long evolutionary history.
It’s possible that the common ancestor of cuttlefish, flies and humans had limbs of some sort. Perhaps the animal used these genes to map the coordinates in other three-dimensional body parts, even one located entirely inside the body.
In later generations, animal lineages evolved profound differences. When it comes to limbs, flies and other insects are as different from cephalopods as they are from us. They have hard exoskeletons, with muscles pulling on them from the inside.
But every time a new kind of limb evolved, it seems, animals did not need a new way to tell cells where they were located inside it. Evolution reused the same genetic program over and over again.
“We’re looking at something ancient,” Dr. Cohn said.