单选题 .  ①The main exception to primate researchers' general pattern of ignoring interactions between males and infants has been the study of male care among monogamous primates. ②It has been known for over 200 years, ever since a zoologist-illustrator named George Edwards decided to watch the behavior of pet marmosets in a London garden, that among certain species of New World monkeys males contributed direct care for infants that equaled or exceeded that given by females. ③Mothers among marmosets and tamarins typically give birth to twins, as often as twice a year, and to court the female in her staggering reproductive burden the male carries the infant at all times except when the mother is actually suckling it. ④It was assumed by Kleiman that monogamy and male confidence of paternity were essential to the evolution of such care, and at the same time, it was assumed by Symons and others that monogamy among primates must be fairly rare.
    ①Recent findings, however, make it necessary to reverse this picture. ②First of all, monogamy among primates turns out to be rather more frequent than previously believed (either obligate or facultive monogamy can be documented for some 17-20 percent of extant primates) and second, male care turns out to be far more extensive than previously thought and not necessarily confined to monogamous species, according to Hrdy. ③Whereas previously, it was assumed that monogamy and male certainty of paternity facilitated the evolution of male care, it now seems appropriate to consider the alternative possibility, whether the extraordinary capacity of male primates to look out for the fates of infants did not in some way pre-adapt members of this order for the sort of close, long-term relationships between males and females that, under some ecological circumstances, leads to monogamy! ④Either scenario could be true. ⑤The point is that on the basis of present knowledge there is no reason to view male care as a restricted or specialized phenomenon. ⑥In sum, though it remains true that mothers among virtually all primates devote more time and/or energy to rearing infants than do males, males nonetheless play a more varied and critical role in infant survival than is generally realized.37.  The author the passage mentions the work of Hrdy primarily to ______