A dour view of human nature has been dominant,"" writes Hunt (The Universe Within, 1981, etc.), "". . .since the time of the Greeks."" But growing scientific evidence, sifted with, care by the author in this well-researched study, reveals that humanity is as kind as it is cruel. Hunt's litmus test for human selflessness is altruism, ""Behavior carried out to benefit another at some sacrifice to oneself, and without, or not primarily because of, the expectation of rewards from external sources""--behavior that, as he emphasizes, contradicts the vision of humanity as survival-driven beast that has dominated most scientific thinking for a century. After establishing through anecdotal histories--of heroes who gave their lives for others, volunteers working suicide hot-lines, people who hid Jews during WW II--that altruism does exist, Hunt explores, citing scores of case studies, the altruism research that's burgeoned in the post-Skinnerian years since 1970. Under the receptive mantle of the relatively new disciplines of sociobiology and cognitive psychology, dozens of often morally committed scientists, he details, have investigated the whys and hows of altruism: for example, the Univ. of Kansas' Daniel Batson, whose complex social-interaction experiments have pointed to ""empathy""--as opposed to societal pressure, for instance--as a likely basis for altruism. In conclusion, Hunt finds altruism to be a trait potential or actual in nearly all, one influenced by heredity but also by environment--and so he concludes with a look at pedagogical and legal means--e.g., ""character education"" courses--to create an altruistic society. Solid, personable popular science with a particular appeal for those who see the proverbial glass as half-full.