Pleistocene Flirting Versus Modern Dating

Suppose that the level of fascination, happiness, and good humor that our ancestors felt in another individual's company was a cue that they used to assess the individual's mind and character. If an individual made you laugh, sparked your interest, told good stories, and made you feel well cared for, then you might have been more disposed to mate. Your pleasure in his or her presence would have been a pretty good indicator of his or her intelligence, kindness, creativity, and humor. Now...

The Scheherazade Strategy

Because verbal courtship is mutual, we might expect men to feel equally frustrated by women lapsing into habitual silence as a relationship ages. This seems less often lamented, either because men develop less hunger for conversation, or because women maintain their verbal courtship effort at a higher pitch for longer. Earlier we saw that male mate choice grows stronger later in courtship, as men may be tempted to abandon a woman after she has become pregnant, and search for a new woman. In the...

Sexual Fidelity and Romantic Love

Sleep around with too many people, and your lover will probably leave you. Sexual choice is not just the power to initiate relationships, but the power to end them. Our capacity for sexual fidelity, imperfect though it may be, is a result of our ancestors favoring the faithful by breaking up with the unfaithful. As David Buss has emphasized, humans have evolved specialized emotions for detecting and punishing infidelity in sexual relationships, distinct from our instincts for detecting cheats...

Breasts

By definition, all female mammals have mammary glands that produce milk for feeding offspring. Any discussion about the evolution of breasts has to take this mammalian heritage as the starting point. Milk-substitute manufacturers have worked very hard for almost a century to convince women that they are not mammals and have no business breast-feeding. Even many science journalists support this view, as when some recent research was reported as showing that breast-feeding raises IQ by five...

The Runaway Brain

Did the runaway sexual selection process play a role in the evolution of the human brain To see how this would work, take the previous example, and in the place of bird, substitute hominid meaning one of our ape-like ancestors that walked erect. For long tail, substitute creative intelligence. If hominid males varied in their creative intelligence, and if that creative intelligence was genetically heritable, two out of three prerequisites for sexual selection would be present. The only other...

Pleistocene Mating

If we could look at the Earth through an extremely powerful telescope a million light-years away, we could see how our ancestors actually formed sexual relationships a million years ago. Until NASA approves that mission, we have to combine evidence from several less direct sources the sexual behavior of other primates, the sexual behavior of modern humans who live as hunter-gatherers, the evidence for sexual selection in the human body and human behavior, and psychological findings on sexual...

Sports as Fitness Indicators

This discussion of bodily condition brings us to our first example of a human mental ability that evolved through sexual selection the capacity for sports. The ability to invent and appreciate new ways of displaying physical fitness is a distinctly human ability. The ritualized behaviors evolved by other animals to intimidate sexual rivals and attract mates almost always include costly, hard-to-fake indicators of physical condition. Male red deer roar at each other as loud as they can, showing...

Sexual Selection in Primates

In most primate species, the distribution of food in the environment determines the distribution of females, and the distribution of females determines the distribution of males. When food is so dispersed that females do best by foraging on their own, males disperse to pair up with the lone females. This gives rise to monogamous couples. It is a fairly rare pattern among primates, limited to gibbons, some lemurs, and some African and South American monkeys. When food comes in patches large...

Theres More to Morality than Kinship and Reciprocity

Kinship and reciprocity are important, and explain a great deal of human behavior that looks initially puzzling from a survival-of-the-fittest viewpoint. Matt Ridley made a good case for their evolutionary social, and economic significance in his book The Origins of Virtue. However, they hardly touch some of the moral virtues we consider most important. Parental solicitude and nepotism are widespread, adaptive, and important, but are not often praised as distinctly moral virtues. Reciprocity is...

Sexual Selection and Venture Capital

Let's go back to the Microsoft example. We saw that large corporations could grow from a couple of entrepreneurs by hiring employees one at a, time. Evolution's threshold problem is more of a finance problem than a personnel problem. How did Microsoft grow large enough to reach the threshold of profitability Like most companies, it survived in the early days through bank loans, venture capital, and stock issues. It didn't grow just from the profits it made. It grew because people were willing...

Supercalifragilisticexpialidocious

Given that the word blue exists, why does the word azure exist They are nearly identical in meaning. It is hard to envision a situation in which natural selection would favor the hominid who could say The sky on the other side of that mountain was azure over one who could say It was blue. Perhaps poetic words like azure were invented for some special ritual or religious function. But why then do we also need cobalt, sapphire, ultramarine, cerulean, and indigo Human vocabulary sizes seem to have...

Bowerbirds

Human ornamentation is distinctive because most of it is made consciously with our hands rather than grown unconsciously on our bodies. However, this does not mean that its original adaptive function was different. One of the very few other animals that spend significant time and energy constructing purely aesthetic displays beyond their own bodies are the male bowerbirds of Australia and New Guinea. Their displays are obvious products of female sexual choice. Each of the 18 existing species...

Matching Pennies

John von Neumann had an astonishingly creative mind, even compared with other Hungarian mathematicians. By the age of 30 in 1933, he had developed the modern definition of ordinal numbers, specified an axiomatic foundation of set theory, and written a standard textbook on quantum physics. When he worked on the Manhattan Project, he had a key insight about how to make the atomic bomb work, and he also originated a fundamental concept of computer science, the Von Neumann architecture. But these...

The Clitoris and the Orgasm

In most species in which males have a penis, females have a homologous organ called the clitoris. Homologous means that both organs grow from the same kinds of cells in the fetus. Anatomically, the human clitoris has the same three-part columnar structure as the penis a glans, a shaft, and bifurcating roots. The main differences are that the penis is much larger overall, its shaft protrudes much more from the pelvis, it keeps blood from flowing back out when aroused, and it has a tube down the...

Indicators for Qualities Other than Fitness

When trying to attract a sexual partner, heritable fitness is not the only thing worth advertising. When males and females cooperate to rear offspring, they should care about more than each other's good genes. They should seek mates in good health because they are more likely to survive as partners and parents. They should seek mates capable of efficient cooperation and coordination, so they make an effective team. Since health and future cooperation cannot be assessed directly, they must be...

Age and Fertility

The most important quality that indicators advertise other than heritable fitness is age. Obviously, age is not directly heritable. A 40 -year-old woman will give birth to a nine-month-old, just as a 20-year-old woman will. However, age has a dramatic effect on fertility, especially in women. Individuals before puberty are infertile. Female adolescents are significantly less fertile than 20- year-olds. Female fertility declines gradually during the thirties, and declines steeply after age 40....

From Fitness Matching to Fitness Indicators

The fitness-spreading effect is interesting, but it doesn't take us very far in understanding the evolution of the human mind. To do that, we have to ask how fitness matching affects the fitness indicators themselves. What follows is admittedly a subtle and speculative argument, but one I think is critical to understanding how sexual selection shaped the human mind. In the above description of fitness matching, it was assumed that individuals could perceive each other's fitness with perfect...