European Stars And Stripes (Newspaper) - April 22, 1986, Darmstadt, Hesse                                Page 16 the stars and stripes tuesday april 22, 1986 searching for the benefits of sex by the new York times t he subject of sexual reproduction an exasperate Dcharles Darwin concluded More than a Century ago is As yet hidden in  it still is. But the origins of sex have become the subject of a spirited debate among biologists who Are pondering theories that Range from the prostate to the bizarre. None of these new theories is flattering to males of any species. At Best males Are portrayed As useful sources of genetic variety. One theory justifies males As storehouses of redundant information that females can draw on if necessary to repair damaged genes. Another describes sex As a sort of disease with males Mere agents of contagion. Sexual reproduction the Exchange of genes from two parents to produce offspring is ubiquitous in nature. It is practice by nearly All animals and plants and in a crude Way even by viruses. Yet according to the current understanding of How evolution works non sexual methods of reproduction should reign instead. Despite decades of research biologists Are still unable to explain Why sex is so common or indeed Why such an ungainly method of procreation Ever evolved. The relevance of sexual reproduction is a major unresolved mystery asserts George c. Williams an evolutionary biologist at the state University of new York at Stony Brook. Experts in evolution and genetics find the pervasiveness of sex to be simply improbable. What s most obvious about sex is How costly it is observed Richard e. Michod of the University of Arizona who is co editing a Book on its origins. Look at the Energy the time the body structures that Are devoted to finding a mate and bearing a  evolution rewards those individuals who Are most successful at passing on their genes to surviving generations. Yet through sexual procreation which involves mixing her genes with those from a male a female is diluting her evolutionary endowment by half. By this reasoning then a female who could reproduce asexually should have an enormous evolutionary advantage. Over the sons scientists say natural selection should have favored parthenogenesis procreation without males who would seem to be nothing More than evolutionary parasites. Since most species retain sexual reproduction despite its seeming inefficiency Williams said it follows that it must provide advantages great enough to be Worth the enormous  these enormous benefits of sex if they exist remain out of grasp. The search for such powerful evolutionary advantages has yet to produce really convincing results Williams concluded. It is not enough the scientists observe to say that sexual urges in animals Are Strong or that sex feels  evolution also produced sex in plants and microorganisms which presumably have no feelings. And in any Case the question is Why creatures with sexual instincts have triumphed in natural selection. A photo recombinant Dan molecule stretches from lower left to upper right magnified 30,000 times by Electron Microscope. What no one disputes is that sex is pervasive and persistent. It All started some three billion years ago among photocells in the primordial soup some scientists believe. As evidence they note that even the simplest known forms today such As influenza viruses that Are nothing More than packets of genetic material sometimes engage in a simple form of genetic recombination involving two or More viruses. In the Fossil record billion year old spores provide the earliest evidence of meiosis the Complex form of sexual reproduction now practice by most plants and animals. Virtually All animals reproduce sexually most of them exclusively so although some lizards fish insects and lower orders switch from sexual to asexual modes or in rare cases reproduce Only asexually. The nearest asexual relatives to humans Are certain lizards the populations of which Are entirely female. In the Plant world sexual reproduction is also predominant although most plants can also propagate themselves vegetatively via roots or shoots. Perhaps 10 percent of flowering plants can produce seeds either sexually or asexually but exclusively non sexual procreation is rare. Scientific debate about the evolution of sex has heated up since the 1960s, when advances in the understanding of evolution demolished the previously accepted explanation. Since the late 19th Century most biologists had believed that sexual species had an advantage because they produced new genetic combinations More often speeding up the appearance of advantageous mutants. Scientists assumed that sexual species thus gained an evolutionary Edge Over species that lacked this Means of genetic mixing. But theoretical work in the 1960s showed that natural selection usually works at the level of the individual not the species. A trait must promote the survival of the offspring of individuals or their close relatives if it is to become embedded in the population. Today according to Michod three main explanations for the existence of sex Are under discussion. The mainstream View conveyed in most biology textbooks stresses the evolutionary gains that individuals derive from having genetically varied offspring. Versions of this first approach see genetic variety As beneficial for different reasons. It could increase the chances that at least some offspring will be Well suited for survival in changing or unpredictable environments. Or varied Young May be the Best Able to exploit Many different niches in a Complex ecosystem. A recent version argues that genetic change is necessary if organisms Are to stay ahead in the never ending race to maintain resistance against dangerous parasites and diseases which tend to evolve quickly. These variation based theories appear quite plausible but even their proponents agree that they have not been satisfactorily confirmed in experiments and Field observations. None seem to have the sweeping explanatory Power that the ubiquity of sex demands the scientists lament. The second approach developed by four University of Arizona scientists also regards sex As having adaptive value but  a different reason its role in repairing damaged genes and thus assuring consistency rather than diversity in offspring. From the beginnings of life these scientists observe solar radiation natural chemicals and other agents would have damaged genes in photocells or other primitive organisms. Only those that could gain a second undamaged copy of the same Gene achieved by fusing with a second organism would successfully reproduce. The More Complex forms of sex that later emerged which involve production of complementary male and female reproductive cells such As a sperm and an egg perform the same damage repair service and also mask the effects of deleterious mutations. Males Are a Way of providing redundant information according to Michod. When females Are damaged they can use information from males to repair their bad  sex is Basic to life because accurate replication of cells is Basic to life said Michod. Damages Are unavoidable and you need repair  a third approach developed mainly by two Canadian scientists Michael r. Rose and Donal a. Hickey departs radically from the prevailing Wisdom because it denies that sex necessarily carries any evolutionary Benefit. Instead it portrays sex As a mechanism for the contagious spread of parasitic bits of Dan. Scientists have discovered that some sequences of Dan similar to viruses spread through populations of cells and higher organisms. Studies of bacteria have shown that some such parasitic sequences actively seek out and penetrate new cells. According to the theory the genetic Exchange that is sex might have first developed As a Means by which parasitic Dan insured their spread. Once this mechanism got rolling said Rose of Dalhousie University there would have been selection pressures on the organisms and the parasites to make sex Cost free or perhaps  if sex does have adaptive benefits he said these Only came into play after the process began. Sex might reasonably be seen As a form of disease that animals and plants have Learned to adapt to Rose said