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MAN AND HIS GENES* F. M. BURNETi To anyone except a recluse, the infinite diversity of human beings is both obvious and delightful. In ordinary casual conversation there is probably more talk about other people's behavior and personality than on any other topic. As a professional biologist who in recent years has become more and more involved with genetic facets of medicine and human biology, I thought that the best subject I could offer for a series of talks on human problems was to discuss some of die implications which, modern genetics would suggest, arise from that diversity. Much of what I have to say will be concerned with differences in the individual and social behavior of men and women, but I want to start with some genetic qualities of men that are more amenable to precise scientific study. In a short talk I shall have to assume a minimal knowledge ofbiology, and I shall say no more about genetics than to stress that its major concern is with thedifferences between individuals and how such differences pass from one generation to another There are several levels at which differences can be demonstrated. First, the biochemical level. There are now many ways of isolating and characterizing chemical components of the body in very great detail. To take a well-known example: each of us belongs to one or other of four blood groups—O, A, B, or AB—and there are precise rules by which those qualities are transmitted. Ifboth parents are O, all the children will be O's, while an AB and an O will have children equal numbers ofwhich are A and B but there will be no O's and no AB's. There are hundreds of similar examples in which a particular protein, ususally an enzyme, may occur in dozens of slightly different but easily detected chemical patterns . In all cases these are regularly inherited in what we call Mendelian fashion. Such chemical differences are well understood as resulting from mutational change in the structural genes which control their synthesis. Sometimes, but by no means always, one of these chemical patterns will¦"Substance of an address given at Trinity College, University of Melbourne, June 26, 1977. tDepartment of Microbiology, University of Melbourne, Parkville, Victoria 3052, Australia .© 1978 by The University of Chicago. 0031-5982/78/2 104-0020J01.00 Perspectives in Biology and Medicine · Summer 1978 \ 505 be so far from the normal one that it cannot function properly, and a child born with that pattern will be obviously ill and perhaps die in a few weeks or months after birth. The second level is the anatomical one. With the rarest exception, everyone can recognize with complete certainty any one of a dozen or two close friends or relatives from any of the 4 billion other people on the earth. Even more definitely, no human being will ever be mistaken for a chimpanzee, or vice versa. There are infinite variations in the shape ofthe face among individuals, and many others less easily recognized in all other parts of the body. A good zoologist will of course find differences in every bone and every organ between man and chimpanzee. Curiously enough, however, there is quite extraordinarily little difference in the biochemical makeup of the two species. Minor anatomical differences seem to be related to a different type of gene—not a structural gene which simply lays down the chemical structure ofthe body's proteins, but a regulatory or control gene which can be thought of as being mostly concerned with ordering, a group of structural genes to become active and synthesize protein and then at the appropriate time turn them off and call up another group. Much ofthe growing edge of genetics is concerned with this regulatory DNA—all genes are made of that miraculous substance—and most of the changes that are important in evolution arise as a result ofmutation affecting the structure of regulatory DNA. The third level is the genetic control ofthe complex functional systems of the body—the interactions of the hormones, the cardiovascular system , or the controls that maintain the quality of the blood, for example. At the present time, my...

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Additional Information

ISSN
1529-8795
Print ISSN
0031-5982
Pages
pp. 505-514
Launched on MUSE
2015-01-07
Open Access
No
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