Some Genetic Aspects of Sex

FPROM the genetic point of view it is advantageous to begin by considering sex in the broader sense of sexuality. It is not generally realized that genetics has finally solved the age-old problem of the reason for the existence (i.e., the function) of sexuality and sex, and that only geneticists can properly answer the question, "Is sex necessary ?" There is no basic biological reason why reproduction, variation and evolution can not go o01 indefinitely without sexuality or sex; therefore, sex is not, in an absolute sense, a necessity, it is a "luxury." It is, however, highly desirable and useful, and so it becomes necessary in a relativistic sense, when our competitorspecies also are endowed with sex, for sexless beings, although often at a temporary advantage, can not keep up the pace set by sexual beings in the evolutionary race and, wheii readjustments are called for, they must eventually lose out. Thus sexual beings form most of the central and the continuing portions of the evolutionary tree from which ever and again new sexless end-twigs sprout off. Whatever the secondary needs of present-day somatoplasm may be, there is no fundamental protoplasmic need for rejuvenation of the germ plasm through sexual union, no reason to believe that "protoplasmic stimulation" is per se produced by mingling of unlike germ plasms, nor any evidence that variation of the hereditary particles is induced by "panmixia." A more reasonable claim might be made out for the new genetic concept of "heterosis" as furnishing the function of sexuality and