How Sex Works:

Why We Look, Smell, Taste, Feel, and Act the Way We Do
Dr. Sharon Moalem

Book Review by Rob Hardy

Sex fascinates us; it makes or breaks marriages, ruins political careers, and is the backbone of the internet entertainment industry.  And yet it is something hidden, as if we were ashamed at its fascination.  In my work, I always ask people who come to see me what they do for fun.  Of thousands of replies to this question over the years, I have had exactly one person list sex.  Surely there are a lot more people than that who find sex something to do for fun.  And besides being fun, sex is interesting.  It is one of those universal activities that you can never learn everything about or participate in all its variants.  There are many enthusiastic guides about how to have sex (the best of them is The Guide to Getting It On!), but if you are more interested in why we have sex and why people do the sexual things they do (including yourself), you are bound to gain insight from How Sex Works: Why We Look, Smell, Taste, Feel, and Act the Way We Do (Harper) by Dr. Sharon Moalem.  The author is a neurogeneticist, evolutionary biologist, and physiologist, but he is used to writing for a popular audience, and this book gives lots of facts, from trivial to essential, about a topic that is always interesting.  If you had a good sex ed. class (bet you didn’t), many of the subjects in Moalem’s book may be familiar, but there is new research in many aspects of sex and new ways of understanding its evolutionary importance, and Moalem has incorporated much of it in a readable and amusing fashion.

First things first: Setting aside coitus, why do we kiss?  This is a question that has made people wonder for centuries.  Kissing has nothing to do directly with reproduction, and plenty of sexual animals don’t do any mouth melding.  Not even all humans do it; the Inuit and Maori don’t practice “the rubbing of the noses” as Darwin simplistically referred to the practice, but they do sniff and nuzzle rather than joining lips.  Kissing feels good, and it’s fun, two aspects that provide a partial explanation for almost all the activities described in this book.  A couple’s first kiss is important; in fact, in a recent study, “Sex Differences in Romantic Kissing Among College Students: An Evolutionary Perspective,” most of the respondents said that they had had the experience of being attracted to someone but losing interest after the first kiss.  The kiss represents information exchange - you take in and give off olfactory, tactile, and behavioral information when you kiss someone, the sorts of nonverbal signals that our animal predecessors sent each other.  In a riff that Moalem repeats throughout, the signals just may tap into our unconscious drive to find someone whose genes are just different enough from our own.

That’s probably connected to why we (and so many other creatures) have sex in the first place.  Sex is pretty costly, and that isn’t just because of the price of dinner and a movie.  It takes energy, and putting two half-cells together to make a new starter cell for a new individual is enormously complicated and can go wrong in countless ways.  On the plus side, it jumbles the genes every generation, which not only makes it hard for parasites and viruses to ride along, but also allows variation in every new individual, enabling evolution to make its changes.  Jumbling the genes may be something we are programmed to do.  Part of our immune system is known as HLA, and a robust HLA means good immunity.  A more robust HLA is something you are granted from birth if your parents had dissimilar HLA genes for the jumble.  It would thus make sense for people to be sexually attracted to people with dissimilar genes, but lacking DNA detectors, how could they arrange this?  They could do it by scent.  Everyone knows that scent is important to sex and is the foundation of a billion dollar perfume and cologne industry, but the experimenters testing mere human scent had to make sure subjects used no such artificial smells.  In one experiment, no-artificial-scent men slept in tee shirts two nights in a row, and then the tee shirts were presented to women to smell and rate for attractiveness.  Women found more attractive the scent from the tee shirts of men whose immune systems had just the right degree of difference from their own.  Moalem reviews visual cues of attractiveness, especially symmetry, while allowing that much of this science is tentative and just beginning.  There are also physiological studies: the more attracted a woman was to her partner, the easier and more intense were her orgasms; good orgasms produce more of the hormone oxytocin, which is thought to increase bonding.  It’s a nice positive feedback system, and indicates how essential good sex is to a good relationship.

It would be a sorry sex book that didn’t have pages on penis size.  Guys, it’s time to relax: although only 55% of you are happy with the size of your penis, 85% of women were quite satisfied with their partner’s penis size (and though Moalem doesn’t say so, some of the remaining 15% must have had dissatisfaction with too big, not too small).  But size does matter: condoms have to fit, especially non-latex condoms, which don’t have the stretch of the typical rubber.  Moalem describes working for an agency in Thailand where western visitors to brothels reported that condoms were breaking.  The problem was that local Thai condoms were smaller than those fit for men from the West.  So measuring erect penis size is important, but it is hard to do scientifically: “Scientists have been measuring penises for more than sixty years, but there’s still no consensus on what to measure, where to measure, or who should measure.”  If men measure their own penises, surprise!  The results are skewed to the larger.  Despite folklore, there is no correlation, Moalem reveals, between shoe size and penis size (and, one assumes, to nose size, either).  Of course Moalem goes into the complicated electrical and hydraulic systems that produce the anatomical miracle of erection.  Some animals have a bone to give them erections, but although for our own we rely on blood pressures, there can be such a thing as penile fracture.  It happens if the guy is too eager and rams the thing in for a hard initial stroke, but misses and hits, say, the woman’s pubic bone.  Who says a sex textbook isn’t practical?  “If it ever happens to you, put your penis on ice (a bag of frozen vegetables will do) and get yourself to the emergency room and ask for a good urologist pronto.”

There are controversies even in science about the dimly-lit biology of coitus.  Moalem agrees (despite some studies to the contrary) that there is a physiological G spot.  The ancient Greeks and plenty of other observers have been telling us there is such a thing as female ejaculation, and Moalem cites modern experts who say it isn’t just a myth, though perhaps not every woman can do it and no woman should feel she is missing something without it.  Focusing in one chapter on homosexuality, he points out that it seems to be programmed into the behavior of literally hundreds of species, part of a bonding mechanism between social animals.  There is research that in at least some cases in humans, there is a gene that directs women to like men, and thus have more children; the same gene in men can cause them to like men.  It’s not all that simple; there are studies to show that a baby’s fetal environment might play a role, and then of course there’s all that post-birth nurture stuff.  Moalem is interested in how technology is helping us overcome medical problems of sexuality, but also mentions “teledildonics” which is sexual remote interaction through the internet.  There is little moralizing here.  Connected to his review of male circumcision (which might have originated as a health practice but certainly took on a life as its own, including wrongly being thought to reduce masturbation), Moalem is strongly condemnatory of female circumcision.  That’s not the typical tone of his book, though, which in many chapters is a jaunty review of the most modern research on an old, old topic.  Improved understanding can’t hurt; one in five American high school girls, for instance, has no idea how HIV is transmitted.  Moalem says that sex is one of evolution’s greatest gifts; but so, too, is our intelligence to understand things scientifically.  His book is an invitation to apply that intelligence in order to understand sex better, and what is strongly linked, to enjoy it more.

Rob Hardy
July 2010

How Sex Works
(Harper, April 2009; ISBN-10: 0061479659)
Available at: Amazon | Barnes & Noble

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© 2010 Rob Hardy. All rights reserved. Content may not be copied or used in whole or part without written permission from the author.

About the Reviewer: 
Rob Hardy is a psychiatrist who lives in Columbus, Mississippi, with his wife, two terriers, five cats, and goldfish.

He reviews nonfiction for The Times of Acadiana, but has been reviewing books as a hobby for years before that.
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