Researchers have uncovered the genetic details that tie together the narrative of how a fin and a hand are related.
Published in the Proceedings of the National Academy of Sciences by Andrew Gehrke, a graduate student at the University of Chicago, this study makes clear the genetic link between the fin and the hand. The reseachers found a common genetic link between an ancient fish which still exists today and mammals with hands, comprised of wrist and digits. They studied the spotted gar, a fish native to North America.
The fossil record makes it clear that fins and hands are closely related. The problem is matching up the small genetic details in order to get a rigorous understanding of the link. This study looks at particular sets of genes in the spotted gar and genes for the development of hands in mice. The spotted gar switch genes for fins inserted into mice functioned almost exactly as the mice’s own genes. A switch gene is a term used to describe how genes are turned off and on during gene expression. The number of genes that a mouse has for hands however, is greater than the number of genes that a spotted gar has for a fin. Researchers are now curious as to whether or not reversing this process would lead to a fish developing hands instead of fins. The result of that process would clear up any uncertainties concerning their findings.
The idea of the fin-hand connection is not new. Fossil records have suggested this connection for quite some time. Gehrke’s research demonstrates the first genetic evidence for this evolutionary transition, which appeared evident on the macroscopic scale but an enigma on the genetic scale.
The problem in the past was researchers were using Teleost fish, a species which did not have enough similarities in their DNA sequences to those in a group of genes such as Hox genes for this link to be viable. When researchers compared the Hox genes of the spotted gar to those of the Teleost fish, the comparison was uncanny. Hox genes are responsible for controlling body planning during embryonic developement.
Studies like this provide evolutionary biologists with a strong foundation in their observations of the fossil record. More research in this branch of biology will help scientists understand more fully the phenomenon of evolution, its history and its mechanisms.
