The Mating Mind
The Mating Mind

The Mating Mind

Theories based on the survival of the fittest can nibble away at the edges of human nature, but they do not take us to the heart of the mind. (Location 149)

Evolutionary biology works by one cardinal rule: to understand an adaptation, one has to understand its evolved function. The analysis of adaptations is more than a collection of just-so stories, because according to evolutionary theory there are only two fundamental kinds of functions that explain adaptations. (Location 170)

to appreciate that selection for survival and selection for attracting sexual partners are distinct processes that tend to produce quite different kinds of biological traits. (Location 190)

Natural selection takes place as a result of challenges set by an animal’s physical habitat and biological niche. (Location 194)

The evolutionary pressures that result from mate choice can therefore be much more consistent, accurate, efficient, and creative than natural selection pressures. (Location 203)

For example, some of us fall in love with people for their quick wits and generous spirits, and we wonder how these traits could have evolved. (Location 209)

If animals cannot see the shapes of one another’s heart ventricles, then heart ventricles cannot be directly shaped by sexual selection—vivisection is not a practical method for choosing a sexual partner. (Location 214)

During human evolution, sexual selection seems to have shifted its primary target from body to mind. (Location 218)

It puts the mind in an unusual position, as both selector and selectee in its own evolution. (Location 232)

Positive-feedback systems are very sensitive to initial conditions. Often, they are so sensitive that their outcome is unpredictable. (Location 237)

Sexual selection is the premier example of social selection, and courtship is the premier example of social behavior. (Location 262)

They played sometimes with homicidal or rapacious violence, and sometimes with Machiavellian strategizing, but more often with forms of psychological warfare never before seen in the natural world: conversation, charm, and wit. (Location 265)

Adaptations for courtship are usually highly developed in sexually mature adults but not in youth. They are usually displayed more conspicuously and noisily by males than by females. (Location 269)

They show conspicuous differences between individuals, and those differences are often genetically heritable. (“Heritable” implies that some proportion of the differences between individuals in a particular trait are due to genetic differences between individuals.) (Location 272)

But over 99 percent of animal species thrive with brains much smaller than a chimpanzee’s. Far from showing any general trend towards big-brained hyper-intelligence, evolution seems to abhor our sort of intelligence, and avoids it whenever possible. So, why would evolution endow our species with such large brains that cost so much energy to run, given that the vast majority of successful animal species survive perfectly well with tiny brains? (Location 323)

The third problem is that nobody has been able to suggest any plausible survival payoffs for most of the things that human minds are uniquely good at, such as humor, story-telling, gossip, art, music, self-consciousness, ornate language, imaginative ideologies, religion, and morality. (Location 335)

This is because the three problems create a paradox that cannot be solved by thinking in terms of survival of the fittest. (Location 349)

Sexual selection cuts through this Gordian knot. Biologists recognize that sexual selection through mate choice is a fickle, unpredictable, diversifying process. (Location 364)

Nor should we be surprised at the lack of survival benefits while brain size was tripling. The brain’s benefits were mainly reproductive. (Location 369)

The courtship ornaments that our species happened to evolve, such as language and creativity, happened to yield some completely unanticipated survival benefits in the last few thousand years: (Location 371)

We imagine evolution toiling away for millions of years, aiming at human culture, confident that the energetic costs of large brains will someday pay off with the development of civilization. (Location 375)

Instead of dancing around in physical space like normal animals, these primates use language to dance around in mindscapes of their own invention, playing with ideas. (Location 384)

Any particular courtship conversation may look trivial, but consider the cumulative effects of millions of such conversations over thousands of generations. (Location 386)

They started selecting one another for their brains. Those brains won’t invent literature or television for another hundred thousand years. They don’t need to. They have one another. (Location 390)

For example, an overreliance on archeological data may lead scientists to underestimate the antiquity of some of our most distinctive abilities. (Location 405)

Historically, European archeologists tended to focus on European sites, but we now know that our human ancestors colonized Europe tens of thousands of years after they first evolved in Africa a hundred thousand years ago. (Location 406)

Any theory of human mental evolution should, I think, strive to meet three criteria: evolutionary, psychological, and personal. (Location 485)

Females may produce more and healthier offspring if they mate with healthier males. (Location 916)

realized that an arms race between female preferences and male ornaments, far from undermining the theory of sexual selection, could offer an exciting possibility for explaining sexual ornamentation. (Location 929)

In the space of a few pages, Huxley managed to confuse sexual selection with natural selection, and failed to distinguish natural selection due to competition between individuals and natural selection due to competition between species. (Location 951)

Unhealthy, unfit peacocks can’t afford big, bright tails. The ornament’s cost guarantees the ornamented individual’s fitness, and this is why costly ornaments evolve. (Location 1050)

Wherever males had sexual ornaments, females seemed to show sexual choice, just as Darwin predicted. (Location 1071)

For example, without sexual selection theory, 20th-century science had great difficulty in explaining the aspects of human nature most concerned with display, status, and image. (Location 1096)

They also code for the adaptations used in mate choice, the sexual preferences themselves. What the physical environment is to natural selection, sexual preferences are to sexual selection. They are not only the tastes to which sexual ornaments must appeal, but the environment to which they must adapt. (Location 1120)

All biological traits show variation. Usually, much of that variation is heritable (that is, due to genetic differences between individuals), so longer-tailed males will tend to produce longer-tailed offspring. In other words, tail length varies and tail length is heritable, satisfying two out of Darwin’s three requirements for evolution. (Location 1154)

After mating, the choosy females start producing offspring. Their sons have longer-than-average tails that they inherited from their fathers. (Their daughters may also inherit longer tails—a phenomenon we shall consider later.) (Location 1161)

Fisher’s runaway process is driven by this genetic correlation between sexual traits and sexual preferences in offspring, which arises through the sexual choices their parents made. (Location 1169)

The only other requirement would be for hominid females to develop a sexual preference for creative intelligence, for whatever reason. If they did, then males with higher creative intelligence would attract more sexual partners and produce more offspring, assuming our ancestors were not completely monogamous. (Location 1180)

The human brain’s evolution clearly looked as if it was driven by some sort of positive-feedback process. Other theorists proposed other candidates for the positive feedback. (Location 1190)

For runaway to work, some males must prove so attractive that they can copulate with several females to produce several sets of offspring. (Location 1212)

The least attractive males, as a rule, must be left single, heartbroken, and childless. Sexual competition must be almost a winner-take-all contest. (Location 1213)

It means rather that a few males mate often and produce many offspring, and most males mate rarely, producing very few offspring.) (Location 1216)

The more polygynous they were, the more potent runaway sexual selection could have been. The modern understanding of human evolution suggests that our ancestors were moderately polygynous—neither as polygynous as elephant seals, gorillas, or peacocks, nor as perfectly monogamous as albatrosses. (Location 1219)

It is a weakness if you expect evolution to be predictable and deterministic, able to explain exactly why one ape species evolved creative intelligence while another did not. (Location 1265)

But evolutionary speed is relative. The human mind’s evolution was actually much too slow to be explained by a single runaway event. (Location 1280)

This speed problem might be solved by supposing that human brain evolution, like the evolution of almost everything, happened in fits and starts. There were short periods of relatively fast evolution when selection pressures were pushing in some direction, and long periods of stasis when selection just maintained the status quo against mutation. (Location 1291)

But that would beg the question of why all the runaway events increased rather than decreased brain size. In principle, a species could stumble into runaway sexual selection for the dumbest possible behavior produced by the smallest possible brains. (Location 1302)

The best analysis has been done by Arthur Jensen in his 1998 book The g factor, and he concluded that “The sex difference in psychometric g is either totally nonexistent or is of uncertain direction and of inconsequential magnitude.” (Location 1330)

A strong version of this theory might suggest that human culture has been dominated by males because human culture is mostly courtship effort, and all male mammals invest more energy in courtship. (Location 1339)

Demographic data shows not only a large sex difference in display rates for such behaviors, but male display rates for most activities peaking between the ages of 20 and 30, when sexual competition and courtship effort are most intense. (Location 1342)

If all sex differences in human behavior are due to sexist socialization, then it may be appropriate to dismiss all cultural and historical evidence concerning a greater male propensity to produce noisy, colorful, costly displays. (Location 1346)

Before contraception, a man’s reproductive success would have increased with his number of sexual partners, without limit. (Location 1397)

The more time and energy you devote to growing and raising children, the less time and energy you can devote to driving off sexual competitors and seducing sexual partners. (Location 1407)

Quality becomes the issue. Each of the female’s offspring inherits half of its genes from whatever male she chooses. If she chooses an above-average male, her offspring get above-average genes, and are therefore more likely to survive and reproduce. (Location 1419)

As long as the males of a species invest very little in their offspring, they have no reason to refuse to copulate with any female. (Location 1422)

Speaking and listening use many of the same language circuits. The production and appreciation of art probably rely on similar aesthetic capacities. (Location 1486)

Almost all human pregnancies arise in sexual relationships that have lasted at least several months, if not years. Modern contraception has merely reinforced this effect. (Location 1538)

But men get much choosier about medium- and long-term relationships, because their opportunity costs increase dramatically. If they are in a sexual relationship with one woman, it is very difficult to sustain a sexual relationship with another woman. (Location 1541)

At first glance, mutual choice seems to offer a solution to the problems posed by the runaway brain theory. It accounts for the sexual equality of brain size and human intelligence that the simple runaway model can not explain. (Location 1562)

Take any population with mate choice that is not totally monogamous, and runaway will occur sooner or later, going off in some direction. Runaway is endemic in sexual selection. (Location 1569)

Incest is a bad idea because blood relatives often inherit the same mutations, which are not masked by normal genes when close relatives produce offspring. (Location 1629)

Many biologists are coming to the view that mate choice is a strategy for getting the best genes you can for your offspring. (Location 1651)

Perhaps the human mind’s most distinctive capacities evolved through sexual selection as fitness indicators. We could call this the “healthy brain theory,” in contrast to the runaway brain theory. The healthy brain theory suggests that our brains are different from those of other apes not because extravagantly large brains helped us to survive or to raise offspring, but because such brains are simply better advertisements of how good our genes are. (Location 1674)

If sexual selection favored the minds that seemed fit for mating, our creative intelligence could have evolved not because it gives us any survival advantage, but because it makes us especially vulnerable to revealing our mutations in our behavior. (Location 1680)

Physical fitness is still environment-relative in the sense that a fit human could not thrive on a neutron star with gravity a billion times stronger than the Earth’s. (Location 1749)

and we expect it to be manifest in real behavior. Indeed, what intelligence researchers call “general cognitive ability” or “the g factor” could be construed as mental fitness. (Location 1761)

This is why romantic novels include adventure and risk: emergencies bring out the best in heroes and the worst in pretenders. (Location 1784)

genetic mutations influence fitness, fitness influences condition, condition influences the state of fitness indicators, fitness indicators influence mate choice, and mate choice influences evolution. (Location 1788)

As David Buss and others have argued, strong mates offer protection, social intelligence brings social benefits, and kindness signals commitment. (Location 1798)

Matt Ridley’s book The Red Queen lucidly describes how arms races between parasites and hosts could maintain the incentives for mate choice. (Location 1901)

As we saw before, mutations almost always lower fitness. The more mutations an individual carries, the lower its expected fitness. To avoid mutational meltdown and extinction, selection (Location 1926)

with Veblen’s conspicuous consumption principle, the form of the cost does not matter much. What matters is the prodigious waste. (Location 2059)

the human brain’s distinctive power is its ability to advertise a lot of the computational abilities that were already latent in the brains of other great apes. This does not mean that music, art, and language came for free just because an ape brain tripled in size. But it might mean that when sexual selection seized upon the ape brain as a set of possible fitness indicators, the genic capture process recruited a lot of pre-existing brain circuitry into human courtship behavior. (Location 2107)

Our brains are only 2 percent of our body weight, but they consume 15 percent of our oxygen intake, 25 percent of our metabolic energy, and 40 percent of our blood glucose. (Location 2153)

violates our values of humility, decorum, and tact. Sexual status hierarchies based on fitness violate our belief in egalitarian social organization. The idea that people sort themselves into sexual pairs by assessing each other’s fitness violates our romantic ideal of personal compatibility. (Location 2169)

They could have included mental quirks that make us prefer novelty to boredom, grace to clumsiness, knowledge to ignorance, logic to inconsistency, or kindness to meanness. (Location 2213)

The gateway may have heavy security. It may be guarded by decision-making systems that must be charmed or circumvented. It may respond only to secret passwords or badges of office. (Location 2230)

Signals are for the good of the sender, not the receiver. They are sent to manipulate behavior, not to convey helpful information. (Location 2236)

Typically, males of most species like sex regardless of their fitness and attractiveness to the females, so they tend to treat female senses as security systems to be cracked. (Location 2244)

Dots would work, but thin parallel stripes would be even better, displaying more edge information per unit area. Perhaps stripes became popular sexual ornaments across many species because stripes are optimal stimuli for activating the visual cortex. (Location 2304)

Why would any animal evolve a pleasure-meter? I think that the main benefit of a unified pleasure system is that it simplifies learning by allowing the hot chooser to use similar kinds of reinforcement learning in many different contexts. (Location 2394)

Courtship behaviors would evolve that simply activate the pleasure centers, influencing the hot choosers to mate with their manipulators. That sounds bad. But is it? (Location 2402)

This makes the computer metaphor very poor at helping psychologists to identify mental adaptations that evolved through natural and sexual selection. (Location 2446)

This entertainment metaphor suggests that the human mind shares some features with the entertainment industry. The mind has to be open for business, with a clean, safe, welcoming interior. It needs good public access routes and good advertising. (Location 2451)

Its emphasis on beauty over strength, fiction over fact, and dramatic experience over plot coherence, reflects popular taste, and popular tastes are what it lives on. (Location 2466)

To understand the human mind’s evolution, we have to remember that reproductive success is evolution’s bottom line. The mind makes very little sense as a Swiss army knife or a military command center. (Location 2471)

The human brain is fickle: it responds much more positively to some stimulation than to other stimulation. Nobody knows in advance what stimulation will work, though some can make some good guesses. (Location 2476)

Sexual selection for pleasure and entertainment explains why so many sexual ornaments like the human mind are pleasing and entertaining. It draws attention to the role of sensation, perception, cognition, and emotion in sexual choice. (Location 2527)

Animals do have incentives to mislead potential mates about their fitness. Coins make a better analogy for sexually selected traits than do watch-faces. Numismatists are familiar with the two criteria of successful coins: they are hard to counterfeit (a requirement that increases with their monetary value), and they are attractive to the eye and the hand. Coins indicate value just as watches indicate time. (Location 2540)

In sexual selection, traits that began as indicators tend to grow more complexly ornamental because the sensory preferences of the opposite sex partially impose their own aesthetic agenda on the indicator. (Location 2568)

Once King Croesus invented official coinage, we could have predicted that most city-states of the ancient Mediterranean world would adopt coins, would make them hard to counterfeit, and would ornament them with some pleasing designs. (Location 2585)

But an innovation’s ability to trigger an adaptive radiation millions of years after its origin cannot explain why it evolved. (Location 2612)

The easy, most general problem is: how can a qualitatively novel structure arise through gradual, quantitative changes? The answer, of course, is that the whole universe unfolds by processes that turn quantitative change into qualitative novelty. (Location 2615)

Capitalism depends on foresight, and evolution has no foresight. The problem of evolutionary innovation boils down to this: evolution needs something like a venture capitalist. It needs something that can protect the very early stages of an innovation against the ravages of the competitive market and the laws of bankruptcy, by granting it some line of credit. (Location 2669)

If the male protobirds happened to combine their forelimb displays with energetic jumps during courtship, and if females selected for the best jumpers, then the transition from a display function to an aerodynamic function would be relatively smooth. (Location 2721)

Our lineage did, so we imagine those survival advantages as projecting all the way back to the mind’s origins. (Location 2736)

Sexual selection thus works as a natural source of serendipity in evolution. It gives evolution the slack it needs to play around without demanding that every cost incurred now must yield some future economic benefit. As all scientists know and most governments forget, this is the only way that productive research and development happens. (Location 2743)

The Flintstones cartoons depicted a prehistory of capitalist affluence, suburban family values, and chaste monogamy. In these Gardens of Eden there is no hint of reproductive competition, the engine of evolution. (Location 2819)