Book Review

Shellberg, Tom (2012) Choosy Women and Cheating Men: Evolution and Human Behavior. Denver, CO: Outskirts Press. ISBN: 978-1-4327-8272-6. 204 pages. US $ 12,95.

Johan M.G. van der Dennen (University of Groningen, the Netherlands)

This charming book(let) resulted from an Evolution and Human Behavior course that its, now retired, author, Tom Shellberg, taught at the Biology Department of the Henry Ford Community College, Dearborn, Michigan. It is intended as an introduction to evolutionary psychology for the lay reader. “This book is more generally about how evolution has shaped our biological predispositions and inclinations and instincts which evolved many thousands of generations ago, many of which we have shared with our animal relatives for millions of years” (p. 3). And the author succeeds in his task, teaching students to ask ‘why’ (ultimate) questions about life, very well. These are some of these ‘why’ questions explored in this book:
● Why do men and virtually all male animals have such a “wandering eye” interest in the possibility of sex with new sexual partners?
● Why do humans in all cultures show the same basic male-female differences as occur in other animals?
● Why do we have so much non-procreative sex, and what are the natural evolved purposes of sex?
● Why do we play as do other mammals? Why don’t most animals play? Why do youngsters play the most and why do we tend to get neophobic as we get older?
● Why such interest in team sports especially by men, why are we patriotic, and why are we so easily inclined to go to war?
● Why do we give tall men so many advantages, and why do we lower our heads and bodies when we feel deferential or when we are appeasing?
● Why do we instinctively like sweets and salt and fat, but not bitter or rotting foods? Why do we think some people are beautiful, and why do we think certain body features are sexy?
● Why are we usually more altruistic to our relatives and why can altruism often be better described as selfishness?
● Why are most people religious?
● Why do we age and therefore die?

All these ultimate questions have been raised and more or less satisfactorily answered by evolutionary psychology, sociobiology, (human) ethology, behavioral genetics, and related disciplines, and now sympathetically and effectively, and sometimes humorously, popularized (in the most positive sense) by Shellberg. The adage of this project clearly is: “Nothing in biology makes sense except in the light of evolution” (Dobzhansly).

Chapter 1: Biology and human behavior
In “The Dark Ages of Behavior Study”, the author wonders why biological or evolutionarily-informed explanations of human behavior were ignored or denied for so long and why the Standard Social Science Model came to dominate the study of human behavior in anthropology, sociology, psychology, etc. Basic male-female differences in humans are very much the same as they are in our animal relatives, especially in sexual and aggressive behavior. Why did so few social scientists fail to realize the significance of the fact that we are animals after all?

Chapter 2: How to answer “why” questions about life
Shellberg first makes it perfectly clear that ‘why’ questions (about ultimate vs. proximate causation) are not to be confused with teleological or “good-for-the-species” answers. Animals never behave for the good of the species, but even if they did, the benefit to the species would be, at best, the result of these behaviors, not the cause. It was Darwin’s great contribution to science and philosophy that he showed us to answer why questions about life.

Chapter 3: The Coolidge effect and human affairs
Males who are genetically inclined to lose interest after mating and to be much more sexually attracted to new females, leave more offspring, so genes in males for attraction to new females spread rapidly by sexual selection. This so-called Coolidge effect constitutes a basic sex difference.

Chapter 4: Why men pay for dates and women choose their mates (Why men and women are different)
Many behaviors good for the goose have not been good for the gander and vice-versa. Robert Trivers realized that the most essential difference between males and females is the unequal amount of parental investment in offspring. “This is the Rosetta stone, the critical starting point, if one is to understand the different evolutionary paths of male and female behavior” (p. 36). This is why women tend to be choosy (and require potential mates to provide resources for them) and why natural selection has shaped males to be relatively promiscuous and indiscriminate. Ironically, because of female choice, philandering males have been largely designed by coy females. The double standard in sexual matters makes evolutionary sense.

Chapter 5: Instinctive attractions and aversions
Humans have many instinctive attractions to what feels good, and aversions to what feels bad, and the same general rule usually applies: if it feels good it usually is good for survival and reproduction, and if it feels bad it is not. Pleasure and pain feelings are only adaptive for animals capable of memory and learning and modifying their behavior accordingly. We appear to have many innate biases, such as beauty and sex appeal, symmetry and baby-like features, even landscape preferences.

Chapter 6: Concealed estrus, sexy bonobos, porcupine dildos and gay rams (evolution and the purposes of sex)
Humans have far more sex than most animals, and most human sex is non-reproductive. Concealed estrus and continuous sexual interest when pregnancy is impossible evolved in human females because it was very advantageous to those women; it kept their men around for more sex tomorrow. There were important evolutionary advantages for males too. Our close relative, the bonobo, is the only species which has more sex than we do, is the only species in which estrus is concealed, and in which social bonding is the main purpose of sex. Because of all this sex, bonobo interactions are much less aggressive than those of any other primate species. The author does not venture into the ultimate question why anisogamy and sexual dimorphism evolved at all, and why there are (only) two sexes.

Chapter 7: Tall bishops and genuflection genes
Men in positions of public authority and leadership tend to be significantly taller than average. “Our heightist bias is deeply ingrained. It’s ancient and irrational and largely subconscious” (p. 79). This heightist bias is explained by the fact that in species where male individuals physically compete for resources such as food or territory, it is usually an advantage to be bigger, or at least to look bigger, than one’s competitors. This is especially true of polygynous species (most mammals), where males physically compete for females. Appeasement behaviors, respectful deference, crouching, etc., symbolically communicating subordination and lack of threat evolved for the same reasons.

Chapter 8: Why charity begins at home (kin selection)
In this chapter, the author introduces Hamilton’s kin selection or inclusive fitness theory, which focuses on the gene as the unit of natural selection, and which finally made sense of many puzzling facts about animal and human traits, such as alarm calls in many social species, helpers at the nest, male coalitions in lion prides, differential altruism to children versus stepchildren, etc.

Chapter 9: Vampire bats, Mother Teresa, and true love (reciprocal altruism)
Many animals, from vampire bats to chimps share food with non-relatives, as do successful hunters in primitive societies, and many animals groom non-relative to remove parasites. Are these examples of pure unselfish altruism? Usually not, according to sociobiologists and evolutionary psychologists. The individual who is helping a non-relative is actually helping himself. It’s called reciprocal altruism (RA). You scratch my back and I scratch yours. The idea was first formulated by Robert Trivers. For RA to work it is only necessary that the benefits to each party exceed the costs. Themes: soliciting support in fights – punishment of defectors – moral and ethical behavior evolved because they serve to reproduce our genes – self-deception – seemingly altruistic behaviors are often self-serving – our extraordinary capacity for empathy and love may have begun by the bonding of mothers and babies.

Chapter 10: What’s fun and what’s done
Why are mammals (and a few birds) playing and what is play? Most scientists who study animal behavior believe that play is basically practice behavior. Play is an instinctive program for learning. On the other side of the medal, we also instinctively, automatically become bored. Boredom has evolved to keep us learning. Themes: old dogs and new tricks: about curiosity and neophobia.

Chapter 11: Homo vestigius
We have all sorts of useless body parts left over from our past evolution. Biologists call them ‘vestiges’. Like all animals we humans have been extensively prewired by our evolutionary history. No theory of human behavior which ignores our ancient biological behaviors will ever explain much about us. Themes: vestigial behaviors – why do vestiges persist?

Chapter 12: Football, patriotism, women, and war (Evolution and own-groupism)
Perhaps our most harmful vestigial behavior today is our easily-stimulated own-groupist inclination to be hostile to other groups within our species who are different from us. We have a genetic predisposition which inclines us to own-groupism; an instinctive us-versus-them predilection to favor our own group, and to compete aggressively, often with hostility, against other human groups. Team sports cannot be adequately understood without reference to biological behaviors shaped by our evolutionary past. Nor can we understand why we are patriotic, or why we wage war. The flip side of altruistic cooperation with members of one’s own group is antagonism toward other groups. Interestingly, it is coalitions of males (“bands of brothers”) who engage in aggressive team sports and war. Of hundreds of societies studied, there is not one documented case of women forming aggressive coalitions to wage war, and the major reason why men evolved to be more warlike was for reproductive access to women, and women’s favoring warriors as sex partners. Furthermore, patriotic allegiance to one’s group was highly adaptive for millions of years of human evolution.

Chapter 13: Why are people gay?
The evidence is overwhelming that in animals and humans homosexuality is biologically determined during prenatal development, that testosterone level is part of the proximate explanation, that genes are usually involved, and choice has nothing to do with it. Because homosexuals usually show gender-atypical behaviors by the time they are two or three years old, the claim that homosexuality is a choice would require the ridiculous premise that toddlers are choosing to be gay. Shellberg assumes that genes for homosexuality must produce some reproductive advantage for relatives of homosexuals or they would become very rare or extinct.

Chapter 14: Unintelligent design
Intelligent Design is a very dumb idea. We humans and other organisms are loaded with many features which demonstrate very bad, inefficient, and even hazardous design. Imperfect (and not intelligent) design is exactly what you’d expect from the process of natural selection.

Chapter 15: Why are people religious?
The most important proximate reason why people are religious is that children are indoctrinated by adults. Many thinkers believe that our need for meaning is so great that our ancestors, lacking any scientific answers to profound questions about the nature of the world and the meaning of human existence, invented gods, and they naturally imagined those gods to be like very powerful people. Belief in supernatural beings, gods and spirits, provided answers and explanations and made existence orderly and meaningful and appealed to the non-rational, emotional parts of the brain, and thus reduced fearfulness and stress and anxiety, and made people feel they were in control, and thus gave them hope, by praying to the gods and appeasing them. Shellberg cites Nicholas Wade, who provides an additional perspective on why religiosity could have been favored by natural selection. Groups fortified by religious belief would have prevailed over those that lacked it and genes that prompted the mind toward ritual would eventually have become universal. Religion emboldened our ancestors to give their lives in the defense of their group against outsiders.

Chapter 16: Why we age and die (And why we won’t someday)
Senescence is the predictable genetically-programmed deterioration of organisms which usually begins approximately at the time of reproductive maturity. Why? The much-quoted Medawar/Williams theory of antagonistic pleiotropy is rejected by Shellberg because it assumes that what matters is the survival of individuals, whereas individuals are more adequately envisaged as temporary survival machines for genes. He therefore proposes – and this is quite innovative as far as I can tell – that the genes which cause us to deteriorate and therefore die have been favored by natural selection because they cause senescence. If individuals lasted indefinitely they would be competing with older, less fit models and this competition would reduce the survival of the newer more fit models. Thus genes which got the old models off the streets at an optimal time would do better than genes which permitted the older, less fit models to exist indefinitely. Voila – the evolution of senescence. Shellberg sketches a horror science-fiction scenario (in my view) that one day we might live for ever. “We age because of genes which program us to age and therefore die. We can very likely block those genes, so we remain indefinitely with bodies like those of twenty-year olds”.

Chapter 17: Evolution in the third grade
Darwin, Hamilton, Wilson, Dawkins, and many others showed us how to understand the meanings of life. The field of Evolutionary Psychology got its start in the 70’s and has been growing rapidly ever since. Perhaps the most important impact of the modern revolution in evolutionary science has been on the study of human behavior. The British government has recently passed legislation which makes evolution education compulsory as of September 2011 in the primary schools of England – this in sorry contrast to many countries in the modern world, including the USA, where evolution is not even included in high school biology classes.

I would recommend this charming book to my students, were it not for the “Introductory Textbook Paradox”: the awkward fact that students interested in the evolution of human behavior do not, in my experience, need such introductions, I’m afraid, at least in the European countries I am acquainted with. Students would already know, at least in outline, about natural selection, kin selection, sexual selection, reciprocal altruism, sex/gender differences and ultimate versus proximate explanations; about Darwin, Wilson, Trivers, Dawkins, and Hamilton. Nevertheless, in the United States the book may be badly needed.

Finally, it is, in my opinion, a serious omission and a missed opportunity that the book has no references, and not even a “List of Recommended Further Reading”.