Networks Under Construction

As biologists figure out more about how life is, they can then figure out how it got to be that way. First there were genes. Mendel noticed that somehow the wrinkles on wrinkled peas could be transmitted down through the generations, even if some of those generations had no wrinkles at all. It turned out that the wrinkles were the result of a gene; a different version of the gene produced smooth peas. For much of the twentieth century, evolutionary biologists worked out how changes in genes produced evolutionary change. A mutation that alters one position in a gene (or chops out a whole chunk of it) can alter the protein it encodes. As the proteins on a virus mutate, for example, their shape becomes harder for an immune cell to recognize. But towards the end of the twentieth century, it became clear that the protein-coding sequence is not the ...