Modern Genetics Confirm Ancient Relationship between Fins and Hands

http://www.sciencedaily.com/releases/2014/12/141222165441.htm


This article describes how scientists have finally made a conclusive link between the fins of aquatic animals and the human counterpart (comprising of wrists/fingers or ankles/toes) called the autopod. In the past, scientists had studied teleost fish in comparison with human bone structures, which comprise most of the world's commercial fish. However, they were barking up the wrong tree, so to speak. They never found a signatory connection between the two, and a lack of expression of necessary limb-forming genes called Hox genes confirmed this. The Hox genes function using genetic switches that can turn them on and off. While scientists found these genes in teleosts, they did nothing went turned on. The reason behind teleost fish not activating the necessary genes was due to an ancestral split millions of years ago, where speciation made them a separate group from more bony fishes that maintained a similar structure to the autopod. Scientists then studied a fish called the spotted gar, a North American fish with more bony structures than the teleosts. Scientists found that when the gar's Hox genes were activated, autopod-like structures were formed as compared to transgenic rats. This breakthrough showed a direct genetic/evolutionary connection between aquatic life bone structures and human/mammal bone structures, thus strengthening existing ideas about the origin of mammal/human life.

This relates to our current topic of evolution because it shows how homologous structures evolved, and what possible common ancestry might occur between fish and humans. It also relates to genetics in that scientists used methods of genetic fingerprinting to discover this connection (PCR and Gels were most likely used).