The Stone Age Present
by William Allman

Parts of the human brain are socialized to respond to social signals such as smiles, frowns, and other expressions of emotion that form a universal communication system among humans.[21]

Our craving for sweets reflects the fact that in ancient times, sweet, ripe fruits were an excellent--and scarce--source of nutrition. In a modern world filled with an overabundance of candy and other goodies this evolutionary sweet tooth backfires. [22]

No human group is more biologically or psychologically evolved than another. [29]

Those who would like to use the findings of science for political and social purposes find the notion of an infinitely plastic mind attractive. [30]

As our species evolved, we didn't lose our "instincts" rather we proliferated them. [34]

There has not been enough time passed since the dawn of agriculture--which began 10,000 years ago--for any new mental mechanisms to arise in response to our sedentary, urban, industrialized, life.... we still harbor a Stone Age mind within our skulls. [35] "There is this thinking that if other animals can do it, then it can't be real intelligence," says Cosmides. "So behaviors like eating, or finding a mate, or raising a child--all these things that other animals do--are thought to be simple. But when you actually try to work out the kinds of computational procedures you would need to do these so-called simple things, you find it's amazingly complicated." [36]

Evolution would have designed the human brain to be acutely sensitive toward cheaters. [41]

Men appear to navigate not so much by environmental cues as by creating a mental map of the overall pattern of their journey. Women, on the other hand, tend to rely on landmarks and cues from the environment. [45]

Women's primary role as gathers resulted in the evolution of a mind that was adept at keeping track of what kind of objects were in which locations in the surrounding area--remembering that there was a tree bearing fruit, for instance, near a certain part of a particular stream. Such spatial skills would have been vital for a gatherer whore "quarry" is widely dispersed but stationary. [46]

The findings that men and women have fundamentally different spacial abilities--not simply better or worse because of adverse cultural "socialization"-- touches the essence of the evolutionary psychologists impact on the understanding of human behavior. Because psychologists have long regarded the mind as a "general problem solver," differences between the performances of men and women on psychological tests have been characterized as deficiencies, typically thought to be the result of cultural influences. But in the evolutionary psychologist's view of the mind as having been customized by evolution, the minds of males and females are different in subtle ways because their evolutionary history is subtly different. [46]

The incidence of marriage between adults who were raised together on a kibbutz from a young age was far below that of another group who were joined the kibbutz later in their childhood. [47]

In the rare cases where brothers and sisters are separated at birth and reunited as adults, they sometimes fall in love. [48] We have evolved as a species that raises its siblings together.

So when you are being nice to your child, they say, all you are really doing is selfishly trying to propagate your own genes. A lot of sociobiological work carries this cynical interpretation of human behavior--a view of the world for which sociobiologists have been rightly criticized. The problem is that sociobiologists confuse the mechanisms of the mind with the process that built the mind, and in fact these are two separate things. Evolutionary biology is not a theory of human nature. Rather, it is a theory for how human nature came to be--and a useful tool for discovering what human nature actually is. A mother really does love her child--it's not that somewhere deep inside her mind there is a selfish motive to spread her genes. [49]

Cosmides and Tooby argue that the key to understanding how evolution influences our everyday behavior is not the gene but the mind. [49]

"There is proximate causation and ultimate causation," says Cosmides. "The ultimate cause of why people like to eat nutritious food--and not gravel or broken glass--is that our ancestors had food preference mechanisms, and those whose mechanisms led to their having more children thrived, and we inherited their mental mechanisms. But the real reason we eat certain foods is because they taste good!" [50]

"When a woman puts salt on her eggs for breakfast," says Cosmides, "a sociobiologist would attempt to explain such behavior by trying to determine how the presence of salt on her eggs increases the number and fitness of her offspring in the future. An evolutionary psychologist, on the other hand, asks what kinds of psychological mechanisms for craving salt might have evolved in our ancient human ancestors." The difference in explanatory power between the two approaches lies in the fact that even when modern medicine suggests that too much salt may well be harmful--and so may not increase her evolutionary fitness--the news does not diminish the importance of evolution in explaining our everyday behavior.

That's because our everyday behavior reflects the lives of our ancient ancestors in the past--not our attempt to get our genes into the future. "A fast-food restaurant is a little monument to the diet of our ancient ancestors," says Cosmides. "Fast food has all the things that were very hard to get for our ancestors--such as salt, sugar, and fat--and so having an appetite for these things was important back then. Sugar is in fruits, and you can't get too much of them; wild animals don't have a lot of fat on them, so having a taste for fat makes you want to get meat, and you could never get enough of that either. By the same token, our ancestors didn't need an appetite that would cause them to go out in search of fiber, because every plant they ate gave them tons of fiber. Unfortunately, we have inherited those evolved tastes--even though we now have all the fat and sugar we want. But since our ancestors could never get enough of this stuff, we don't have an evolved mental mechanism that says, 'Aha, I've had enough sugar and fat.' We don't want it any less, even though we know the health consequences of it, because it still tastes good." [50--51]

The fact that our evolutionary cousins take a keen interest in the personal affairs of each other perhaps should not come as a surprise to a species that thrives on gossip, newspaper tabloids, and TV soap operas. We are merely the most intelligent and social members of the most intelligent and social family of animals in the world: the primates. [53]

The human brain is three times larger than what might be predicted for a typical primate of our size. [54] In adults, the brain consumes 20% of the energy of the body at rest as opposed to only 9% in the average chimp. Big brains are subject to overheating: a rise of only four degrees in body temperature can lead to fuzzy thinking in adults and convolutions in children A big brain means a big head, which makes giving birth dangerous. [55]

Humans have one of the shortest gestation periods, relative to their overall life spans, of all the primates. If human mothers followed the gestation pattern typical of other primates, they would give birth 18 months after conceiving a child. In fact, at birth, the infant brain is only about a quarter of its adult size. It begins its biggest growth spurt only after a child is born. The human brain is larger than that of other primates precisely because it keeps up this childlike growth spurt long after the brains of other primate infants have stopped growing.

This prolonged, infantlike growth rate in humans--and the big brain that came with it--may have evolved through mutations in the genes that control our overall development: Unlike other primates, our "juvenile" form is extended into adulthood, along with out juvenile rate of brain growth. In fact, human adults resemble infant apes, whose bulging foreheads and flat faces eventually develop into the jutting-chinned, sloped-forehead shape of adult apes. [55-56]

Lucy--an ape's head on a human body. [57]

The human brain is so used to seeing the world in social terms that even toddlers will interpret a simple action between two inanimate objects as a social interaction involving goals, desires, and beliefs. [59]

People routinely yell at their cars, talk to their pets, and curse the weather. [60]

A female baboon cozied up to a male who had just killed an antelope and, coaxing him to lie down with the promise of sex, suddenly snatched the antelope carcass and ran. [63]

Since the ability to form theories about another's mind is a powerful tool for maneuvering through the enormous complexities of social exchanges, creatures having such a trait would have had a tremendous adaptive advantage over creatures who could not do so. [65]

Until about age four, children find it hard to distinguish between what they know in their own mind and what they think is in the mind of someone else. [65]

The human ability to develop a theory of mind about others appears to be a specialized feature of the brain that operates independently of other mental activities typically associated with intelligence. Deficiencies in this evolved mental mechanism may be responsible for autism. [67]

Much of the world of literature, drama, and humor relies on the supreme ability of humans not only to create theories about each character's mind but also to imagine simultaneously how each of these imaginary minds might view the minds of other characters. The tragic nature of Shakespeare's Romeo and Juliet, for instance, comes from a series of misconceptions among the characters that only the audience is aware of. Romeo's suicide is the result of his thinking that Juliet has died, and the audience is aware that if Romeo knew what they knew, the suicide would not have happened. To an audience of monkeys, however, Romeo's actions would make no sense, because they wouldn't be able to distinguish between their own beliefs and his. [69]

Being able to build future scenarios of what might happen as a result of one's actions is a key part of many social exchanges. [69]

To build scenarios of the future, form a theory about someone else's mind, and teach others is vital to any social relationship. [70]

Diamond traders successfully conduct millions of dollars of business with a verbal agreement and a handshake. They know they will see each other again and again, and so must keep their word if they want to continue their business. According to one businessman, "If something comes up you get the other man on the telephone and deal with the problem. You don't read legalistic contract clauses at each other if you ever want to do business again." [84--85]

The World War I trench soldiers' tacit cooperation arose because they faced each other day after day, and so they knew that if they shot at someone today those same people would be shooting at them tomorrow. [85]

Research with "evolutionary" models of Axelrod's computer tournament demonstrates that a world full of programs that are "naively nice"--that is, they merely cooperate all the time--are quickly pounced upon and wiped out by meaner programs. [88] Use this in the golden rule section. Add subsection: Always cooperate.

The ability to "read" a face for signals that indicate helpfulness or hostility has dramatic implications for playing the game of TIT FOR TAT. Unlike Axelrod's tournament, the real world has no requirement that each person play the game with every other person at random. With the ability to identify beforehand which people are more likely to cooperate or defect in an exchange, people can try to interact only with cooperators and avoid potential defectors, increasing the chances for a higher payoff. ... The key is for the "nice" strategies to recognize each other and interact more often with each other than with the public at large. [91]

These emotional expressions are hard-wired into the brain: For most people, the facial muscles involved in shaping the face when they are experiencing emotions are not under conscious control. Only 10 percent of us, for instance, can voluntarily pull the corners of the mouth down to make the prototypically human "sad" face. The rest of us can make this face only while also moving the muscles of the chin, which is a giveaway for a phony expression. Likewise, only 15 percent of people can voluntarily raise their eyebrows at the center of their forehead to duplicate the forlorn look of grief and distress. [95]

For a "me against them" game like poker, showing no emotion gives an edge against the others in the game; in a cooperative game like bridge, showing emotions is so advantageous that it is prohibited by the rules. The fact that most of life is a cooperative game suggests why the emotions continue to play a major role in our day-to-day affairs. [96]

The general strategy of avoiding painful emotions--guilt and shame--and seeking our pleasurable ones--pride and self-esteem--typically has the overall effect of playing a TIT FOR TAT strategy that produces long-term benefits. Honesty is the best policy, if only from the perspective that it reduces the enormous load on one's mental machinery. [98]

People are neither innately selfish nor innately altruistic, precisely because following such a simpleminded strategy is a prescription for disaster. [98]

Numerous studies have shown that the most important factors in reducing stress include being among loved ones and family, and having the time for peaceful contemplation--a description much more fitting for our ancestors than ourselves. [105]

In the vast majority of cases, men reacted more strongly to imagining their lover having sex with another man, and women reacted more strongly to the idea of their lover developing a strong emotional attachment to another woman. [109]

Just as the sexes are different below the neck, they have different mental "organs" above the neck as well. [111]

More than 10,00 men and women in over thirty different societies around the world were asked to rank dozens of physical and psychological characteristics they preferred in a mate. ... After "kindness" and "intelligence" males and females part company in what they look for in mates. In all but one society, for instance, women ranked the attributes of "good earning capacity" and "ambition" in males as more desirable than physical attractiveness; conversely, males considered a woman's youth and physical attractiveness more important than her earning capacity. [112--113]

In nearly every society around the world, men regard unblemished, unwrinkled skin, clear eyes, and full lips as signs of beauty in a woman--which not coincidentally are also signs that the woman is young, healthy, and disease-free, and therefore likely to be fertile for a long time. Men also have a keen eye for a woman's figure: not for whether she is thin or fat, but whether her hips are roughly one third larger than her waist--a proportion indicating a pattern of fat distribution that medical studies have shown is linked to robust fertility. ... Indeed, even though the Miss America winner has become 30 percent thinner over the years, her hip-to-waist ratio has stayed close to this evolved optimum. [114--115]

In the medically sophisticated West, it is sometimes easy to forget that until quite recently one of the leading causes of death among young women was complications in childbirth. ... In some species of seahorses, it is the males, not females, who make the biggest biological investment in rearing offspring. In those seahorses, it is females who exhibit aggressive courtship behavior, and it is males who are choosy about selecting their mates. This suggests that it is the biological logic of who physically invests more in offspring, not merely gender, that influences a creature's sexual behavior. [114]

This evolutionary legacy of what we find attractive about a mate persists in our modern-day psychology, even though in the West, much of the evolutionary rationale for these traits has disappeared. Women typically have only a few children, modern medicine has helped extend fertility well into middle age, and as women gain more financial independence, they are less in need of financial resources from men. Yet the evolutionary legacy of our Stone Age mind continues to fuel our modern-day sexual behavior. [115]

In every case in every culture, women searched for, or married, men who were slightly older than themselves. Men, on the other hand, generally preferred younger mates, with the age difference widening as the man's age increased. [116]

The different elements involved in a long-term or a short-term love affair result in differences in what people consider desirable. For a man seeking a long-term mate, fertility and fidelity are desirable. For a woman seeking a long-term mate, a man's resources and willingness to commit to a long-term bond are important. For people seeking short-term mates, however, the things they find desirable are different. Men want to find a woman who is sexually available and willing--though such behavior is abhorred in a potential long-term mate. In short, they want to gain access to as many mates as possible for the least amount of resources. For women, on the other hand, one main goal of a short-term affair is "resource extraction"--the most extreme example of which is prostitution. Studies show that women who are pursuing a short-term strategy say they prefer "big spenders" on a first date. [118]

Thus the more a man sleeps around, the more attractive he becomes, because the very fact of his success at attracting members of the opposite sex is a trait that a woman may want to pass on to her children. [119]

And whereas only 3 percent of all mammalian species form long-term monogamous bonds between male and female, surveys suggest that more than 90 percent of people the world over marry at least once--though the Western concept of "life-long marriage" is by no means the norm in all cultures. This long-term bonding is a reflection of another unique quirk of human existence: Human infants are virtually helpless at birth and so require the longest and most intense period of parental care among all organisms. [121]

Males and females are more closely matched in size, reflecting a shift to a more monogamous way of life. [122]

If a woman displayed overt signs that she is fertile, a male would be motivated to stay by her only during the short time each month that she could conceive. [126]

If a woman experienced orgasm within one minute before the man ejaculated--or within sixty minutes afterward, the amount of sperm that was rejected dramatically dropped. The findings reveal that a woman's sexual pleasure does indeed have an evolutionary function: controlling the fate of her man's sperm. [128--129]

Males get better assurance of paternity, females get more help, and their children become more fit than children raised without two parents. [129]

With the beginning of agriculture, some 10,00 years ago, however, the choices of men and women suddenly changed. The sedentary life style that came with agriculture meant that men and women could no longer simply split up and go their separate ways if they had differences. ... The current rise in divorce rates in Western society may reflect the growing economic independence of women. [130]

Being dependent on one plot of land for survival meant that people could not simply move elsewhere if a dispute arose between spouses or neighbors, as had been the practice for most of human prehistory. [221]

To make the kinds of biological changes in a plant that make agriculture possible, people must have been actively involved in the domestication process for many generations of the plant before they actually began farming. [233]

Farming the soil produces more food per acre than hunting and gathering, and therefore more people could live off the resources in a given area of land. By making possible a huge population boom, farming became a necessity: With more mouths to feed, there was no way our ancestors could return to hunting and gathering as a way of life. [241]

In erotica geared toward men, women are typically depicted as lusty, aggressive, and enjoying sex for sex's sake, without emotional attachments or courtship. In erotica geared toward women--that is romance novels--sex is part of a greater theme of love, where a man is consumed emotionally by passion for the heroine and no one else. For the heroine, sex is not an act of submission but an act of control, as she masters her man's emotional fate. In other words, erotic materials for both men and women typically present the opposite sex as a caricature of the consumer's own sexuality. [132] "Heterosexual men would be as likely as homosexual men to have sex most often with strangers, to participate in anonymous orgies in public baths, and to stop off in public restrooms for five minutes of fellatio on the way home from work," says Symons, "if women were interested in these activities." [133]

Men are more concerned that their mate has had sex with someone else, while women are typically more concerned with how their mates dispense their resources and attentions. ... As Samuel Johnson put it, the difference between male and female infidelity is that "the man imposes no bastards upon his wife." [134]

About 10 percent of children in North America are born to husbands who believe that the children are their own offspring, when in fact they are not. [135]

Adultery is typically defined in laws around the world in terms of female adventuring outside the marriage, rather than male infidelity. A woman's adultery was punishable by death in seventeenth century England; it is grounds for divorce in many modern societies, and in the not too distant past, laws in several states in the United States regarded killing an adulterous wife as no crime at all. [145]

Studies of child abuse in modern North America reveal that a stepchild is 100 times more likely to be fatally abused by a stepparent. ... a pattern of violence that is unrelated to the parent's socioeconomic status, age, or family size. Small wonder that in folk tales around the world, stepparents are commonly portrayed as villains who pose a danger for children. [146]

Even though the actual rates of murder are different among different societies, the age and sex of the murderers are the same the world over. [148]

Words and sentences are not thought itself, as those who have struggled to find the right words to express how they feel can testify. Language is a notoriously poor method of expressing emotions, feelings, and the richer tapestries of human existence" [171]

There is a sense in which libertarian implies free from jealousy.

For a species that thrives on information, long-lived people are an important resource. [196]

Colder climates make people more reliant on each other for survival.

The gut of the ape is dominated by the large colon--the big, tubelike organ that helps process the tough fibers of plant food--and this testifies to the ape's everyday diet of massive amounts of vegetation. The human gut, on the other hand, is unique among primates in that it is dominated by the small intestine, which is where protein and nutrients are rapidly broken down and absorbed--an anatomical arrangement that suggests that humans have long been eating nutrient-rich foods such as fruits, nuts, and meat. ... the human body can't make vitamins A or B12, two vital substances that are commonly found in meat. [203--204]

Meat is the ideal food for the most cooperative species on Earth: Packed with calories, meat is one of the most compact sources of nutrition going. In every type of environment from savanna to Arctic, hunting large game provides the most calories per hour of work among all the various ways of obtaining food, regardless of whether people are using stone-tipped spears, nets, fishhooks, or bows and arrows. Thus meat is a great bargaining chip in social relations. A person could typically gather and carry about enough plant food for at most only a few people to eat. The carcass of a large animal, however, contains enough food for many people, making it ideal for sharing with friends or neighbors, courting lovers, tending to the sick, or provisioning a family. [204--205]

Evidence that the brain is specially wired to enjoy music comes from people who suffer brain damage from stroke and are afflicted with "amusia." [216]

Our ancestors lived in small groups. ... The number of people we know really well--about 100, as opposed to 500 or 5000--hasn't changed since the time of our ancient ancestors. [247]

A group of religious fundamentalists known as Hutterites limits its group size to 150 people. The reason they give for doing so gets to the essence of the evolution of the human psyche: When their groups are bigger than that, say the Hutterites, individuals can no longer be controlled by social pressure alone. [248]

It took millions of years to evolve the mind within our skulls today, and our species has been living in its radically new surroundings only a few thousand years--far too short a time for any new evolved mental mechanism to arise. [248]

Faced with a sea of anonymous faces as societies grow beyond the 150 or so individuals we can keep track of in our day-to-day social bargaining, people often resort to using simplistic labels--economic, class, or race--to distinguish potential cooperators and defectors. [249]

Year Read: 1996


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