Speculations on the origins of human sexuality ch

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Speculations on the origins of human sexuality ch

  1. 1. SPECULATIONS ON THE ORIGINS OF HUMAN SEXUAL BEHAVIOR<br />Leanna Wolfe, Ph.D.<br />Institute for Advanced Study of Human Sexuality<br />February 9, 2011<br />
  2. 2. When the gods gave people sex, they gave us a wonderful thing. Sex is food: just as people cannot survive without eating, hunger for sex can cause people to die<br />Nisa<br /> The Story of Kung Woman<br />
  3. 3. What’s Unique About Humans?<br />Hidden Ovulation<br />Extended Childhoods<br />Human Infants are the least mature apes at birth<br />Year Round Female Receptivity <br />Irrelevant of ovulation<br />Bonding<br />Serial Pair bonding<br />Polygamy/Monogamy<br />Based on economic, social and cultural factors<br />
  4. 4. Just So Stories…<br />Adam and Eve<br />Mitochondrial Eve<br />Early Emergence of Male Provisioning Female and her Infants<br />Owen Lovejoy<br />Hidden Ovulation emerged to enable Pair Bonding<br />Helen Fisher<br />
  5. 5. Mitochondrial Eve<br />Newsweek’s most popular cover ever<br />The discovery of a relatively recent emergence of Homo sapiens (less than 200,000 years ago) was lost at the thought of there having been a Real Eve…<br />
  6. 6. Extended Childhoods<br /><ul><li>Babies Less Mature at</li></ul> Birth<br /><ul><li> Mothers Require more</li></ul> Provisioning<br /><ul><li> Cultural Learning</li></ul> Important for Survival<br />Advent of the Nuclear Family???<br />Dikika Child<br />3.3 mya<br />
  7. 7. Human-Ape Origins<br />
  8. 8. Distribution of Apes<br />
  9. 9. The Sex Contract<br />Owen Lovejoy, Male Paleoanthropologist<br />A Maasai Tribe Shares Meat<br />Immature young caused females and males to form long term pair bonds in order to facilitate care for the young<br />Ethnographic data from foraging societies establishes that a woman’s offspring will be well-fed simply if she is part of a tribe in which there is at least one good hunter.<br />
  10. 10. A Sex for Meat Exchange?<br />Certainly, but no evidence that it took the form of monogamous pair bonds<br />Successful male hunters might have exchanged their bounties with multiple females, ultimately accessing sexual variety<br />Females in the quest for as much meat as possible might have gladly exchanged sex with multiple male hunters<br />
  11. 11. Bonobo Estrus Displays<br />Bonobo Estrus Display Attracts Attention!<br />Bonobo Full Estrus Display<br />
  12. 12. Human Ovulation Displays…<br />Ovulation Test Kit<br />Measures rise of Luteinizing Hormone, signally impending ovulation<br />Female Showing Lots of Skin<br />(possibly ovulating)<br />
  13. 13. Explanations for Hidden Ovulation <br />Helen Fisher<br />Anthropologist<br />Sarah BlafferHrdy<br />Anthropologist<br /><ul><li>Mate Guarding
  14. 14. Pairbonding
  15. 15. Love
  16. 16. Confuse Males
  17. 17. Prevent Infanticide
  18. 18. Female Independence</li></li></ul><li>Sexual DimorphismAs an Indicator of Polygyny<br />Differences in size between male and female were more pronounced amongst the Australopithecine than modern day humans.<br />
  19. 19. Testicle SizeAs an Indicator of Non-monogamy<br />With their relatively large testicles male chimpanzees are well-equipped for intrauterine sperm wars <br />Humans also have relatively large testicles…<br />
  20. 20. Y-Chromosome Distribution<br /><ul><li>Less diversity than X-chromosomes
  21. 21. Reveals widespread long-lasting polygyny among human populations</li></li></ul><li>Sperm Competition<br />An indicator of polyandrous mating patterns<br />Biologists Robin Baker and Mark Bellis observed that females that engaged in extra-pair copulations retained more of their lover’s ejaculate (70%) following orgasm than their spouse/home partner’s (40%). Thus sperm competition could easily foster high levels of genetic diversity.<br />
  22. 22. Sperm Competition<br />Three unique kinds of sperm (blocker, fighter and egg penetrator) were distributed differently depending on the context of lovemaking.<br />Only Egg Penetrator Sperm could cause a pregnancy<br />Sperm from different males might compete<br />
  23. 23. Reproductive Strategies<br />Male (re: MPI)<br />Cad (low investment)<br />Lad/Pair Bonded Mate (high investment)<br />Female (discerning Mate Value)<br />Monogamous Mate<br />Sexy Son Hypothesis<br />Partible Paternity<br />Extended Family/Tribe/Village/Community<br />
  24. 24. Sexy Son Hypothesis<br />Females seek testosteronated hunks near ovulation while long term bonding is sought with fatherly resource providers.<br />David Buss,<br />Evolutionary Psychologist<br />
  25. 25. Humans are by Nature Hypersexual and Promiscuous<br />S.E. Ex – Socio <br />Erotic Exchange<br />Primeval societies engaged in communal parenting, group sex and were oblivious to paternity<br />Christopher Ryan<br />Research Psychologist<br />
  26. 26. How Males Care About Paternity<br />Dogon Menstrual Huts<br />Contemporary DNA Testing<br />Chastity Belts<br />Female Genital Mutilations (FGM)<br />Post Nuptial Virginity Tests<br />
  27. 27. Why Males Care…<br /><ul><li> Fear of Being Cuckolded into Investing in Someone Else’s Genes
  28. 28. Assured that Just Their Genes Go Into the Future
  29. 29. Pass on Wealth/Resources/Legacy to Heirs</li></ul>When Males Don’t Care<br /><ul><li> When They Are Bonobos
  30. 30. When the State/Community/Village is Responsible for Resources
  31. 31. Exchanging Service/Resources for Sexual Access</li></li></ul><li>Is Chimp Social Sexuality Natural?<br /><ul><li>Visible Estrus
  32. 32. Multi-Male</li></ul> Multi-Female<br /> Troops<br /><ul><li>Social Sexual</li></ul> Hierarchies<br /><ul><li>Mother-Infant </li></ul> Bonds<br />
  33. 33. Is Bonobo Social Sexuality Natural?<br /><ul><li>Females Rule the</li></ul> Business<br /><ul><li>Paternity </li></ul> Irrelevant<br /><ul><li> Homosexuality
  34. 34. GG Rubbing
  35. 35. Penis Fencing
  36. 36. Pedophilia
  37. 37. Disputes Resolved</li></ul> with Sex <br /><ul><li>Group Sexual</li></ul> Bonding<br />
  38. 38. Serial Monogamy: Is it Natural?<br />Lust<br />testosterone<br />Attraction <br />Dopamine<br />Norepinephrine<br />Attachment<br />Oxytocin<br />Vasopressin<br />Detachment<br />
  39. 39. Is Partible Paternity Natural?<br /><ul><li>Multiple Fathers
  40. 40. Cooperative Parenting
  41. 41. Group Sex Rituals
  42. 42. Communal Resources</li></ul>Ache (Amazon) Children Sharing Food<br /><ul><li>Fetal Growth Requires</li></ul> Regular Inseminations<br /><ul><li>Multiple Fathers’ </li></ul> Characteristics Inherited<br />Ache Children with one of their Fathers<br />
  43. 43. Is it All in the Eye of the Beholder?<br />

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