From Scientific American:
For a long time, scientists certainly expected the anatomical differences among animals to be reflected in clear differences among the contents of their genomes. When we compare mammalian genomes such as those of the mouse, rat, dog, human and chimpanzee, however, we see that their respective gene catalogues are remarkably similar. The approximate number of genes in each animal’s genome (about 20,000 or so) and the relative positions of many genes have been fairly well maintained over 100 million years of evolution. That is not to say there are no differences in gene number and location. But at first glance, nothing in these gene inventories shouts out “mouse” or “dog” or “human.” When comparing mouse and human genome, for example, biologists are able to identify a mouse counterpart for at least 99 percent of all our genes.
In other words, we humans do not, as some once assumed, have more genes than our pets, pests, livestock or even a puffer fish. Disappointing, perhaps, but we’ll have to get over it. If humans want to understand what distinguishes animals, including ourselves, from one another, we have to look beyond genes.
More here.
