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Sunday, November 17, 2013

Book Review - Evolution and Human Sexual Behavior

This book was awesome. Answered some questions that I have been wondering for a long, long time. Also easy to read and easy to understand. Quick--doesn't suffer from the "too much info" problem so many books do. There was a ton of stuff that was same-old info I have heard before. But there was also a ton of fabulous new things I didn't know--here are my favorites:

-If you give a female lemur hormonal contraception she will no longer be attractive to lemur males.

-There is substantial evidence that humans, by nature, are monogamous with some polygamy. There are many factors that lead the authors to this conclusion, one is the size difference between men and women: the more polygamous a species, the greater the size difference between the male and female. The more monogamous, the closer in size the male and female are. Another factor is sperm count. Humans have relatively low sperm count which means a guys sperm probably wont have to be competing with another guys sperm to fertilize the egg.

-Many mammals commit infanticide if they don't think it is a good time to raise a child, humans included. The main reason human women commit infanticide is uncertain paternal investment i.e. they know they can't raise the baby alone. Other big reasons are low infant quality (birth defects) and twins (where a female cannot afford to care for both).

-Almost all humans will engage in same-sex sexual activity if that is the only sex that is available to them. Heterosexual guys in prison will have sex with men. Heterosexual concubines living in a large harem will have sex with women. There were many other examples but I can't remember them off the top of my head.

-Female hunter-gatherers are ready to be married when they are around 18. They are proficient enough at gathering and are capable of raising offspring. Male hunter-gatherers are ready to be marred around 25 to 30. Building strength and learning to hunt so you can provide for a family takes a longer. What ends up happening is that young female hunter-gatherers get their sexual needs met in marriage. The male hunter-gatherers have sexual needs but no one to have sex with since the girls their age have married older guys who can provide them with meat. Different societies had different solutions to this problem that, over the years, became culturally ingrained. In quite a few societies older men (possibly because their wives were breast feeding and uninterested in sex) would have sex with the younger men. In other societies post-menopausal women would have sex with the younger men. Over time these practices become highly ritualized with lots of rules and customs to follow. I FINALLY UNDERSTAND ANCIENT GREECE!!!!!! Another way the older males of a society dealt with the 15-25 year olds who kept trying to seduce their wives was to ship them off to war.

-Ancient pottery shows pictures of women holding babies while having sex

-In hunter-gatherer societies, children practice having sex with one another, so do young (infertile) teenagers. This is an expected part of development and preparation for adult life. All monkeys do this as well. Chimpanzees require sexual learning as part of childhood or they wont be able to mate properly when they are grown.

-In almost all societies the sexual practices of children mimic those of the adults--our society is quite strange that we expect our children not to have any sexuality whatsoever.

-Orangutans are known to grab at and and attempt to sexually molest human researchers.

-Nursing offspring (humans and monkeys) will try to prevent their mom from mating--it is crucial for their survival. Since humans used to nurse for 4+ years it makes sense for human children to protest when they see their mother engaging in mating activity (like kissing their dad). Makes so much more sense than Freud's theory.

-Incest taboos began so that societies had access to the resources of others. These taboos exist in most societies. But science shows that incest among first cousins will only increase mortality of offspring by 4%.

-The youth culture we see now would not exist if women still got married and had families soon after they got their periods.

-The Lepcha of India expect girls to have sex by the time they are 11 or 12. It is thought that this is what makes puberty start.

-Human males have small sperm reservoirs, suggesting that human males were designed to ejaculate a couple times a week rather than daily.

-When Asians first saw Europeans kissing they thought it was disgusting.

-There is a notable lack of loud coital vocalizations in the cross-cultural record. It is a fact though that female vocalizations of pleasure will make a male come faster.

-Women's vaginas will "lube up" for sex whether the woman is into it or not. The vagina must do this to protect itself from tearing and other damage.

-Evolutionarily the authors disagree with the idea of sexual dysfunction. They "disagree with the very notion of classifying variation as dysfunction." The average postpartum women will be severely "sexually dysfunctional" by the current definition. The authors disagree with defining what is normal as dysfunctional.

-Hunter-gatherer women will not get their periods for almost 2 years after the birth of a baby. (Depends on how many calories are available to them though)

-The only reason human live past 50 (past making sure their offspring survive) is to help care for their grandchildren. Diminished interest and ability to have sex is adaptive. Older folks are supposed to use their energy to care for their grandkids, not mating. The presence of a grandparent helping to care for the kids is positively associated with survival of children. *Hunter-Gatherer Childhoods addresses this much better than this book (in more depth and this book claims it is only grandmothers while HG Childhoods shows that is not the whole story).

-In some societies it is even taboo for a married couple to continue having sex after all their children are married. Their priorities should be elsewhere.

-The word testimony refers to the practice of holding a man's testicle in your hand while making an oath.

-Today about 1/3 of Americans are single. Just 100 years ago it was aberrant to be single and single people were treated as inferiors.


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