Evolution and Human Sexual Behavior

Evolution and Human Sexual Behavior (pdf) by PETER B. GRAY & JUSTIN R. GARCIA

 Evolution and Human Sexual Behavior (pdf) by PETER B. GRAY & JUSTIN R. GARCIA

While Darwins journals and books inform us of his ideas, his experiments, and his theories, they are largely silent on the most intimate of details. We do know that he was concerned over potentially negative effects of fathering children with his wife and cousin, Emma; the epigraph above reflects this concern, though Darwin’s worries were later assuaged through research conducted by his son George. We do know that his marriage was a fruitful union, for he and Emma had ten children. We also know that, despite any fears of inbreeding, he felt a deep love for his wife and enjoyed a long, committed, marriage to her.

For may we not infer as probably . . . that marriage between near relations is likewise in some way injurious,—that some unknown great good is derived from-the union of individuals which have been kept distinct for many generations?


—Charles Darwin, On the Various Contrivances by Which British and Foreign Orchids are Fertilized by Insects, and on the

Good Effects of Intercrossing

We can make some level-headed guesses about the sexual world Darwin inhabited based on the time and place in which he lived. Rather than attempt to personalize, in a sordid and uneasy way, what actually happened in Charles and Emma Darwin’s bedroom, let us instead imagine a typical couple of the late nineteenth-century English gentry. Doing so will help illustrate how any given individual’s sexual behavior bears the sexual marks of his or her evolutionary ancestors in addition to the cultural environment in which he or she was raised.

Such a generalized person probably had wondered about sex during his or her upbringing, engaged in curious sex play with childhood acquaintances, masturbated during pubertal years, and likely married a long-term partner. Such a person probably had intercourse on a bed, engaged in sex during night hours, presumably in the most typical of sexual positions (the missionary position), and at some point produced offspring. This person likely attempted to shield the children from direct view (and earshot) of parental sex; engaged in less sex during times in which a woman was on her period or late in pregnancy, or in the spell after having given birth to one of her offspring; and this person probably experienced a decline in intercourse frequency with advancing age. These are characteristics of behavior that applied to men and women of the time; with the exception of having sex on a bed, these are also, as we will see, quite typical patterns among people the world over. Yet we will also see variation on these themes (for example, variable liberty granted for masturbation, and variation in potential marital partners).

None of this sexual patterning may strike you as unusual. Now step out of your bipedal shoes and suppose you were a chimpanzee in an African rainforest. From a chimpanzee’s-eye view, what would you think of these kinds of human sexual practices? You might have a host of questions. Why have clothes that require removal? Why have sex on a bed? Why have sex away from one’s offspring and other adults? As a chimpanzee, you know that sex is easier without clothing that interferes with the act; clothing also impinges on one’s ability to readily view the signals that facilitate a sexual encounter, such as a female’s sexual swelling or a male’s erect penis. Sex also works just fine without any special linen surfaces or candlelight—really, any spot will do. There is nothing wrong with sex outdoors, on the ground, and under sunlight. You would also know that sometimes it is preferable to sequester yourself and a partner during sex (away from a dominant male, perhaps, who might be irked if he caught the two of you), but that most times sex in view of fellow chimpanzees is fine. Well, maybe not if you are a mother whose nearby offspring resent your displaced passions and attempt to separate you from your mate (now that is parent-offspring conflict!). You would also puzzle over the missionary position. As a chimpanzee, most of your sexual behavior entails males mating with females from behind. Yet those strange humans rarely resort to that position.

Our imaginary-chimpanzee thought experiment reminds us that we take many details of human sexual behavior for granted. We may not realize that some of these features of our sexuality beg for explanation. We also may not realize how an evolutionary perspective can help contextualize and explain the specifics of our sexual lives. Our aim in this book is to present a concise, accessible, current, and integrative account of human sexual behavior. We seek to cover a wide human sexual terrain, synthesized within an overarching evolutionary perspective. We seek to combine substance with an enjoyable narrative. We hope the readers who come along on our tour will include academics, students, and the curious coffee-shop customer (several sat near Peter in a Las Vegas Starbucks as he wrote many of the words in this book; we wonder how many may have speculated on what he was actually writing about). And we hope that Darwin himself would have enjoyed this evolutionary perspective on human sexual behavior if he were alive today….



  •  The Evolution of Sex, Sex Differences, and Human Sexuality
  •  The Garden of Variety: Cross-Cultural Variation in Human Sexuality
  •  Love and Maybe Marriage: Patterns of Pair-Bonding and Romantic Love
  •  Raising Human Sexuality: Processes of Sex Differentiation and Sociosexual Expression
  • Playing at Sex: Learning, Practicing, and Developing Sociosexual Behavior in Context
  • Welcome to the Party: Puberty and Adolescent Sexual Development
  •  Kinsey Takes Anatomy Class: Human Reproductive Anatomy and Physiology within  Evolutionary Perspective
  • Turning the Key: Human Sexual Response and Orgasm
  •  The Evolution of Baby Making: Mechanisms of Fertility, Infertility, and Variation in Fertility Outcomes
  •  Born to Be Less Wild: Peripartum Shifts in Human Sexuality I I The Sands of Time: Aging and Sexuality
  •  Sexual Revolutions: Contemporary Human Sexual Practices


Language: English
Format: PDF
Pages: 377
Size: 3.57 Mb
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