Cows and Hippopotami Share Ancestors with Whales
 - Common sequences in gene were found -

(translation from "Nihon Keizai Shimbun", 14/Aug/1997)


A research team comprised of researchers from the Tokyo Institute of Technology, etc., concluded from analysis of animal genes a surprising result that cows, hippopotami and whales evolved from a common ancestor. According to the traditional classification, both cows and hippopotami belonged to artiodactyla, but the team proposed a new classification showing that these animals are closer to whales than to pigs and camels. The result was presented in the August 14th issue of British science magazine Nature.

Members of the research team were: professor Norihiro Okada (Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology), researchers from National Institute of Animal Industry (the Ministry of Agriculture, Forestry, and Fisheries), National Research Institute of the Far Seas Fisheries (the Fisheries Agency), and Institute of Cetacean Research.

The DNA of genes is comprised of two parts, those which produce protein, and those which produce nothing and are thus useless. The useless part of DNA contains a special sequence called retroposon. Since retroposon is inherited over generations, the study of the existence of retroposons indicates whether animals evolved from a common ancestor.

In their study, the genes of about twenty animals were analyzed and retroposons common to cows, hippopotami and whales were found. Professor Okada says "Whales and hippopotami look quite different, but they have the same abilities to communicate by sound in the water." In the past, methods such as statistical analysis of the type of all the genes were used to find the ancestors of animals, but it was quite difficult to judge which animals branched in the evolutional process. 



                   +---- Pigs ----- Hippopotami     
                   |                                
                   |                                
                +------- Camels                     
                |  |                                
                |  |                               
          ------+  +---- Cows                      
                |                                   
                |                                  
                +------- Whales                     





                +------- Pigs
                |
                |
                +------- Camels
                |
                |
          ------+  +---- Hippopotami
                |  |
                |  |
                +--+---- Cows
                   |
                   |
                   +---- Whales


Fig. Old classification (above) and new classification (below)

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