Shark DNA for fingers? Is this true?

Question

http://news.yahoo.com/s/livescience/20070817/sc_livescience/howsharkshidetheirfingers

Is this story a hoax or for real? Are there other similar instances of genetic patterns that have existed unused for millions of years that are now a critical component of our DNA?

Answer 1

If the University of Florida is willing to acknowledge it, it's very likely authentic. And it shouldn't be surprising. Parts of DNA perform the function of activation. It's like turning on a switch. If the gene responsible for activation of a function is turned off, that function will not be present in the organism. The state of that switch can be passed on for generations. Later, if that gene is again turned on, the function reappears. If it's inactive, some of the mechanisms for preserving its integrity have no effect, such as natural selection. Over many generations, it is likely to deteriorate, but it's not likely to disappear.

Fingers on a shark would be a detriment, not an asset. They wouldn't be very useful, and they would increase the resistance to movement through the water.

From the design perspective, it's economy of design. DNA is extremely reliable and cheap. If you're building a primate that doesn't need a tail, just take the DNA of a primate with a tail and deactivate the genetic structure for the tail. That's much simpler than removing it entirely.

Answer 2

There are a variety of genes that determine what each segment of the early body will become. These genes tell us which segments will have ribs and which will have appendages such as gills, fins, or limbs. The homeobox genes are associated with the segmented anatomy.

There is a gene that results in small eyes in the mouse if one copy is damaged and no eyes if both copies are damaged. There are drosophila (fruit flies) with a mutation in a similar gene. If you put the working mouse gene in the eyeless fruit fly, the next generation has eyes. If you take the working fruit fly gene and put it into eyeless frogs, the next generation has eyes.

Answer 3

I think it probably indicates that genes that control development are very old and highly retained. It is interesting that a shark is close enough that it still likely has the same parts that became fingers in the bony fishes. There must be some very high evolutionary pressure to maintain those genes and parts since we split from sharks, what, 300 and some odd million years ago?

Answer 4

Seems like many snakes have a hip bone. Kinda looks like a small pelvis. Also the human appendix is kinda like an organ rabbits use to digest grass. In the case of the appendix it's the same thing only in reverse.