In a study such as this one, one must argue that on purely scientific grounds organisms of different sexes and ages respond differently to social stimuli. . . . Among the primates this is well established."" And ""We cannot forget the relevance of genetic transmission of behavioral characteristics."" All of which is to say that women's biological destiny--the three K's--always reasserts itself, and the authors have computer statistics from 34,040 kibbutz members to prove it. ""We have divided people into the simple, widely evident classification of boys and girls, men and women, to see what we can see."" Some of the subjects may have felt uneasy, but they enabled Tiger and Shepher and their research assistants to conclude that, despite sexual freedom, kibbutz women have increasingly taken less responsibility for kibbutz-wide policies and management, and instead focused on family life. This occurred because of ""our mammalian and primate origins and the long, formative hunting-gathering period in our evolutionary past."" The authors deny that they espouse either ""race science"" or the 19th century notion of ""arrested development of the female,"" accusations with which Tiger is familiar since his Men in Groups (1969). They also have little notion of loving, permanent relationships, but prefer to cast women as eternal mothers. The actual causes of these women's ""return to the hearth"" are worth speculating upon--but the book substitutes its own premise for empirical analysis.