1. Human Nature
Ridley’s book explains human nature in terms of sex. The differences between males and females, the larger brains of humans, can be explained by sexual competition. For example, the competitive nature of men is a result of sexual selection. Men who were more aggressive, had more mates and left behind more descendents than men who were not aggressive. This causes men today to be more aggressive than women. (Aggressive women do not leave behind more descendents than passive women). This kind of argument is prevalent throughout the book.
2. Genetic mutiny and gender
Humans practice female exogamy. The sons inherit their parent’s status more than daughters inherit their parent’s status. High status families should prefer to have sons, because wealthy sons can leave behind many descendents. Low status families should prefer to have daughters, as daughters can marry rich men and have children, while poor sons are less likely to have any children at all. Indeed, in feudal times, lords favour sons, sending daughters off to nunneries, while peasants are more likely to leave possessions to daughters.
Why do many cultures favour sons. Is this irrational sexism. Or sons having more economic value?
How to explain dowries, where females buy good husbands. Sons inherit status. Females have to buy it.
3. Peacock’s tale
The sex that invests most in rearing young is the sex that profits least from extra mating. The sex that invests the least has time to spare to seek other mates. Therefore, males invest less and seek quantity, females invest more and seek quality.
Sexual selection theory: The behavior and appearance of an animal Is not adapted for survival but to acquire the best mate. The two can conflict.
Peacocks have long tails because peahens will only mate with peacocks with long tails. But why do peahens like long tails?
One explanation is that they choose long tails because other females also choose long tails. Once most females choose to mate using tail length as criterion, than females who buck the trend and choose a short tailed male will have a short tailed son, and these short tailed sons will have less reproductive success. Female arbitrary preferences have changed male appearances.
Sexy son versus healthy offspring theory
Sex son theory: Peahens prefer beautiful males because they seek beauty to pass to their sons, who may in turn attract females. Males best at seduction are good at other things as well. The more conspicuous his tail, which makes him more visible to predators in the wild, the better his survivability.
Healthy offspring theory: Peahens prefer beautiful males because beauty is a sign of good genetic quality. Symmetry as beauty. Animals’ bodies are more symmetrical if they are in good condition while growing, less symmetrical if stressed.
There is a red queen contest going on between males and females. Peahens are descended from females who made a careful choice of the health and wealth of their suitors, Peacocks are descended from males who made a hardsell, who seduced and lied to their mates.
Seduction is like advertising. And advertisements work. They sell a message about the qualities of the product on offer. Consumers can believe the advertisement or invest effort in learning the qualities of the product themselves. If the cost of the latter is too high, it is better to believe the advertisement. It is better to buy the second best ice cream than to go to the bother of learning about advertising and how it manipulates you into buying second rate ice cream. Similarly, if detecting the dishonesty is costly to the female, it might not be worth it for her to do so.
4. Polygamy and the nature of men.
Parental investment determines which gender will attempt polygamy. The gender that invests less in the rearing of children will have more time to seek other mates. In humans, the asymmetry is obvious: 9 months of pregnancy compared to five minutes of fun. Seahorses are the exception that proves the rule. The female sea horse has a sort of penis which injects eggs into the male’s body. The eggs develop there. It is the female horse who courts the male.
Monogamy confers the advantage of the undivided parental attention of a male, while polygamy has the advantage of the better genes or greater resources that the male provides. Whichever is more advantageous for the female, by ensuring the survival of her descendents, is the system that is adopted.
Wealth accumulation results in polygamy. A hunter-gatherer economy does not favour the accumulation of wealth and does not support polygamy. An agricultural economy allows the accumulation of grain, and does not depend on luck as much as in hunting. The wealthy farmer can acquire more wives.
Social animals seek power. Men do not use brute strength entirely, they use cunning and form alliances to gain status and wealth and sex and whatever they desire.
In 1790, nine mutineers from HMS Bounty landed on the Pitcairn Islands. There were altogether 15 men and 13 women on the island. Eighteen years later, ten women survived, and only one of the men. Of the men, one had committed suicide, one had died, and 12 had been murdered. The surviving male converted to Christianity and prescribed monogamy for pitcairn society.
The human male seeks polygamous mating, uses wealth, power and violence to obtain sex, but not at the expense of monogamous relationship. We still maintain the institution of monogamy because of the female gender.
5. Monogamy and the nature of women.
Why are women unfaithful?
Women seek monogamous marriage and do not seek sexual variety because their reproductive ability is limited not by how many males they mate with, but with how long it takes to bear offspring. An extra mating does not significantly increase the number of children she leaves behind. The costs far outweigh the benefits, as an affair may cause her husband to desert her and leave her without a mate to take care of her children.
Why do women then have affairs when married?
This is because their husbands are almost, by definition not the best male there is. If he was, he would not have ended up with her. So the female wants to have her cake and eat it too. She marries a husband to take care of her young, and has an affair with a genetically superior lover to have children. Stereotypical examples are of females who marry the nice guy and have affairs with the boss, or marry a rich ugly man, but have an affair with a handsome lover.
6. Sexing the mind
Men and women have different minds because of evolutionary pressures. Female minds evolved to suit the demands of bearing and rearing children, gathering plants. Men evolved to suit the demands of rising in a male hierarchy, fighting over women, hunting for meat.
As a result, girls are better at verbal tasks, boys at maths, girls at some visuo spatial tasks like object memory and location, while boys are better at mental rotation.
A clichéd example would be the couple who are lost. To a man, stopping to ask the way is an admission of defeat, which status conscious males want to avoid. To a woman, it is common sense and plays to her strength in social skills.
Why do rich men marry beautiful women?
For men, casual sex presents a small risk but enormous reward. Men who seize such opportunities leave more descendents than men who did not. Because we are descended from prolific ancestors, rather than barren ones, men are more likely to be tempted by casual sex than women.
Women are different. Having sex with a stranger might burden her with a pregnancy before she has won the man’s commitment to rear the child, she might also be exposed to revenge from her husband. There are enormous risks but little reward. So women who accept casual sex leave fewer rather than more descendents, and modern women are likely to be equipped with a suspicion of casual sex.
Men will look for mates that will use his sperm and money to produce babies, he will seek youth and health. Men who seek 40 year old women leave behind fewer descendents than those that seek 20 year old women.
Women who seek power, wealth or fame in a husband leave more descendents among modern women.
Romance novels are aimed entirely at the female market. Sexual acts play a small part in such novels. Instead, the book is about love, commitment, domesticity, nurturing, and the formation of relationships. The romance novel and pornography represent the respective fantasies of both sexes.
7. The uses of beauty
Beauty exists because it works. Beautiful people are attractive because others have genes that cause them to find beautiful people attractive. People with such genes leave behind more descendents than those that do not.
Men prefer a low waist-to-hip ratio. They prefer heavy women with a low waist to hip ratio compared with thin women with a high hip to waist ratio.
Men who choose young women as mates leave behind more descendents. Chimpanzees find middle aged females almost as attractive as young ones. However, chimpanzees do not form lifelong marriages.
A beautiful face is an average, symmetrical face. Facial symmetry is a good clue to good genes or health during development.
What draws women to men? The same things that draw men to women: the face, youth and a figure, but these matter less to women than personality and status. The single exception being height. In a monogamous society, a woman chooses a mate long before he becomes a chief. Women have a strong incentive to be good judges of character. Character traits such as efficiency, courage, and intelligence clue her in on his future potential and are what women find attractive. Body language matters for male sexiness.
People end up married to their equals in attractiveness. Repeated rejection cause us to lower our sights. A string of successful seductions encourage us to aim higher.