THIS BOOK HAS TWO AMBITIONS: ONE EXPLICIT， ONE IMPLICIT.<br > The explicit intention is to present a problem that few peo-<br > ple know even exists， and that is the mystery of males， why<br > they re here and what they re for. The dilemma is best stated<br > with an illustration. Grizzly bear females carry， nurse， pro-<br > tect， and train their young. Male grizzlies take no role in any<br > ，of these activities; they make no obvious contribution at all<br > to the energy needs of reproduction. All those burdens， such<br > as having to hunt and forage for a whole family instead of<br > just for one， fall onto the female s shoulders.<br > Given that fact---and this arrangement is very common in<br >nature--what good are males at all? Why did they arise， or<br >evolve， in the first place? There are many species that get<br >along perfectly well without them. Some of these reproduce<br >without using sex (that is， gene-mixing， or fertilization) at<br >all; in others， all the individuals make both sperm and eggs<br >and then reciprocally fertilize each other. Why are these al-<br >ternatives to males not more widely pursued? Why aren t we<br >all bisexual， with one gonad acting as a testes and one as an<br >ovary (only one of each is necessary for either reproductive<br >role anyway)?<br ><br >