There is an old story of a philosopher who runs when a bear charges him and his friend: "It's no good, you'll never outrun a bear,"says the logical friend:"I don't have to,"replies the philosopher: "I only have to outrun you." (p.33)
Nicholas Humphrey, a Cambridge psychologist, was the first to see clearly the solution to this puzzle: We use our intellects not to solve practical problems but to outwit each other: Deceiving people, detecting deceit, understanding people's motives, manipulating people — these are what the intellect is used for. So what matters is not how clever and crafty you are but how much more clever and craftier you are than other people. The value of intellect is infinite. Selection within the species is always going to be more important than selection between the species." (p.33-34)
One day in 1973, before his beard was so gray, Van Valen was searching his capacious mind for a phrase to express a new discovery he had made while studying marine fossils. The discovery was that the probability a family of animals would become extinct does not depend on how long that family has already existed. In other words, species do not get better at surviving (nor do they grow feeble with age, as individuals do). Their chances of extinction are random.
The significance of this discovery had not escaped Van Valen, for it represented a vital truth about evolution that Darwin had not wholly appreciated. The struggle for existence never gets easier.However well a species may adapt to its environment, it can never relax, because its competitors and its enemies are also adapting to their niches., Survival is a zero-sum game. Success only makes one species a more tempting target for a rival species. (p.64)
Sex is about disease. It is used to combat the threat from parasites. Organisms need sex to keep their genes one step ahead of their parasites.(p.86)
During and immediately after major wars, more sons are born than usual in the belligerent countries as if to replace the men that died. (This would make little sense; the men born after wars will mate with their contemporaries, not with those widowed by the war). Older fathers are more likely to have girls, but older mothers are more likely to have boys. Women with infectious hepatitis or schizophrenia have slightly more daughters than sons: So do women who smoke or drink. So did women who gave birth after the thick London smog of 1952. So do the wives of test pilots, abalone divers, clergymen, and anesthetics. In parts of Australia that depend on rainfall for drinking water, there is a clear drop in the proportion of sons born 320 days after a heavy storm fills the dams and churns up the mud. Women with multiple sclerosis have more sons, as do women who consume small amounts of arsenic." (p.122-123)
There is a good deal of circumstantial evidence that high levels of the hormone gonadotropin in the mother can increase the proportion of daughters and that testosterone in the father can increase the proportion of sons.'°
Indeed, Valerie Grant's theory suggests a hormonal explanation for the returning-soldier effect: that during wars women adopt more dominant roles, which affects their hormone levels and their tendency to have sons. Hormones and social status are closely related in many species; and so, as we have seen, are social status and sex ratio of offspring. How the hormones work, nobody knows, but it is possible that they change the consistency of the mucus in the cervix or even that they alter the acidity of the vagina. (p.123)
Instead, rank determines hormones, which determine sex ratio of offspring. (p.125)
Contrary to popular belief a preference for boys over girls is not universal. Indeed, there is a close relationship between social status and the degree to which sons are preferred. Laura Betzig of the University of Michigan noticed that, in feudal times, lords favored their sons, but peasants were more likely to leave possessions to daughters. While their feudal superiors killed or neglected daughters or banished them to convents, peasants left them more possessions: Sexism was more a feature of elites than of the unchronicled masses.(p.125)
As long as detecting the dishonesty in the signal is costly to the female, it might not be worth her while to do so. (...) It is better to let herself be seduced by a good one than to have the best become the enemy of the good. After all, if she cannot easily distinguish the truthful from the dishonest badge of quality, then other females will not, either, and so her sons will not be punished for any dishonesty they inherit from their father. (p.159)
Where males invest more time or energy in the care of the young, females take the initiative in courtship, and vice versa. (p.180)
In an astonishing study recently undertaken in Western Europe, the following facts emerged: Married females choose to have affairs with males who are dominant, older, more physically attractive, more symmetrical in appearance, and married; females are much more likely to have an affair if their mates are subordinate, younger, physically unattractive, or have asymmetrical features; (p.211)
According to Short, the bigger the testicles, the more polygamous the females. (p.219)
Intriguingly, when female mice choose to mate with males other than those they "live with," they usually choose ones whose disease-resistance genes are different from their own. (p.224)
If he or she is not jealous when I pay attention to another man or woman, then he or she no longer cares whether our relationship survives: Psychologists have found that couples who lack moments of jealousy are less likely to stay together than jealous ones(p.236)
Thornhill went on to argue that just as some people have an incentive to use marriage to concentrate wealth, so other people have an incentive to prevent them from doing exactly that.(p.242)
Intriguingly, men who were conceived and born in periods of great stress, such as toward the end of World War II, are more often gay than men born at other times: (The stress hormone cortisol is made from the same progenitor as testosterone; perhaps it uses up the raw material, leaving less to be made into testosterone.) (p.264-265)
(Matt Ridley - The Red Queen, Sex and the Evolution of Human Nature)
