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Chimpanzees in trees do it It is remarkable that thinking individuals have been slow to analyse an activity as central and profound as sexual intercourse. The subject has long been proscribed by theologians and until lately even neglected by biologists. Things are changing. For animal behaviourists the impact of the past few years has resembled that of the Copernican age for astronomers. A meeting held in Caprarola, Italy, last month went a stage further, taking as its subject the evolution and meaning of human sexual intercourse. Successful mating and reproductive strategies are the motive power of evolution. The bonobo or pygmy chimpanzee (Pan paniscus), unlike the more familiar subspecies Pan troglodytes, has intercourse thoughout much of the ovarian cycle, the clitoris is large, females enjoy orgasm and often solicit sex in the missionary position, and homosexual and masturbatory behviours occur. Richard Wranghan (Harvard) also commented that bonobos are less aggressive than P troglodytes and seem to use sex to reduce tension in the troop-for example, when they fmd a fruit-laden is recognised among some tree. Infanticide primates-a new male may kill the children of his predecessor, as happens in gorillas (Sarah BlatterHdry, Davis, California). Thus one interpretation of female sexual receptivity in bonobos is that it is a strategy to deceive males into accepting the paternity of any baby born into the troop; Ppaniscus makes love not war.1 Molecular biology has revealed that we are more closely related to chimpanzees than they are to gorillas. Bonobos are especially like human beings in engaging in many acts of infertile intercourse. They have been observed to have over 3000 acts of intercourse before the first birth and perhaps 2400 in the rest of their fertile life; women in a preliterate society (characterised by relatively few births and long intervals of breast feeding) may have 2000 to 3000 acts of intercourse in a lifetime, of which perhaps only 200 will be potentially fertile. Biologically and statistically, the key phrase of the 1968 Papal encyclical Humanae vitae-"Every so
act must be open to the transmission of life"-is simply not true. Where was the mistake made? Several clerics explored the evolution of Catholic teaching on intercourse. It transpires that Augustine, a saint who had a lustful youth, contributed most to the thinking of the early fathers of the church on human sexuality. He read Latin but not Greek and, as a result, misinterpreted the Adam and Eve story, believing that original sin was transmitted by sexual intercourse, like some latter-day virus. In addition, rather like the US Food and Drug Administration’s initial refusal to approve it to in because rise tumours DepoProvera gives beagle dogs, Augustine and the writers who followed him almost certainly looked at the wrong species; procreation and sex are indeed inextricably linked in cows and cats although not in apes or human beings. Moreover, until recently, key aspects of reproduction remained hidden. The Church, for example, has condemned rubber condoms which, while interrupting natural processes, also have the potential of saving lives, but does not even comment on rubber nipples for feeding bottles that expose babies to a discernible risk of death. Why should the Billings’ method be more natural than the pill, which, by partly restoring lifelong rhythms of reproduction also reduces the risk of ovarian and uterine cancer later in life? The disconnection between intercourse and ovulation in women is one key to the love between parents and a foundation of the human family from a biological perspective; in some ways identifying ovulation turns a woman back into a monkey. Biologically, the two sexes are in competition and Jack Caldwell (Canberra, Australia) suggested that male control of women and regulation of sex arises most in settled agricultural societies. Once men own the land, the desire to secure paternal rights can make women into chattels. Feminists at the meeting interpreted the Vatican teaching on contraception as a crude extension of male power, while others sought consensus. Vatican II unambiguously endorsed the loving aspects of sex and even Pope John Paul II has written "to say that intercourse is permissible and justified only on condition that the parents hope to have a child as a result would be an exaggeratedly strict ethical position". Dr Francesco De Lorengo, the Italian Minister of Health, emphasised the imperative, in an overcrowded problem-ridden world, to review the Catholic interpretation of intercourse; Cardinal F. Angelini (Vatican) invited theologians and scientists to continue to study the meaning and purpose of human sexual intercourse. If the Guinness Book of Records had a section on medical conferences, the Caprarola gathering would have to go in the "firsts" section; surely now this sexual equivalent of a four-minute mile will be broken again and again.
1. Kano T. The last ape: pygmy chimpanzee behavior and ecology. Stanford, California: Stanford University Press, 1992.