A comprehensive account of how the races differ, and a provocative theory as to why.
Race, Evolution, and Behavior, J. Philippe Rushton, Transaction Publishers, 1995, 334 pp., $34.95.
reviewed by Samuel Taylor
Race, Evolution, and Behavior is one of the most important books about race to be written in many years. Not only does it describe the myriad ways in which the races differ, it advances a persuasive and original explanation for what these differences mean and how they came about. Prof. J. Philippe Rushton of the University of Western Ontario has written a rigorously scholarly book that is not always easy to understand, but it could well become a classic in its field, like Race by John Baker and Bias in Mental Testing by Arthur Jensen.
Just how different are the races? Most experts now take differences in intelligence for granted. Prof. Rushton has gone much farther and marshaled a wealth of data on other important differences. Some of these are summarized on page 3, in a chart that deserves close examination. The most striking finding is not just that Asians, whites, and blacks are different, but that the differences fit a pattern, with Asians and blacks at opposite ends of a spectrum, and whites in the middle.
A large part of the book — and a good portion of this article — are devoted to reviewing these data, but Prof. Rushton’s most provocative and original contribution is his application of what is called r-K theory to this pattern of Asians-whites-blacks. The main features of r-K theory are represented graphically in the drawing on page 3.
Different species have evolved different approaches to propagation. At one extreme is the r-strategy, by which an organism produces a very large number of offspring, but gives them little or no care. The oyster is a good example. Every year it releases millions of eggs into the ocean and leaves them to the mercies of weather and predators. Almost all of them die, but a few survive.
r organisms must mature quickly because they get no help from their parents. The ones that survive repeat the cycle by producing huge numbers of eggs, only a few of which will live. The symbol r stands for the maximum rate of increase in a population, and when the conditions for reproduction are good, an r-strategist can increase its numbers at a terrific rate.
At the other extreme is the K-strategy, which is used by more advanced animals, including man. The number of offspring is much smaller, but great effort is taken to give each one a good chance of survival. K– and r-strategists consequently are very different both in biology and in what Prof. Rushton calls life histories.
K-strategists live longer, have larger brains, and take longer to reach sexual maturity. Unlike the simpler r-strategists, they tend to have some kind of social organization. Besides the care they give their young, adults may share food, cooperate in the hunt, and fight predators together. The K-symbol stands for the carrying capacity of the breeding area, and represents the production of small numbers of offspring that are carefully nurtured for a particular environment.
All humans follow an extreme K-strategy. They have few young, who take years to mature and require a great deal of care. They have large brains and complex societies based on cooperation. However, human races are not identical. The chart on page 3 shows that Asians consistently show more K behavior than whites, who in turn show more than blacks. There is virtually no departure from this pattern.
Maturation and Reproduction
In almost every respect, racial differences in the physiology of reproduction show an r-K pattern that runs from blacks to whites to Asians. Fraternal twinning, for example, which happens when a mother releases more than one egg during ovulation, is clearly an r-strategy of producing more and smaller young, who are more likely to be miscarried, be born underweight, die in infancy, and receive less parental care.
Fraternal twinning is twice as common among blacks as among whites, and twice as common among whites as among Asians. Triplets are ten times more common among whites than among Asians and 17 times more common among Africans than among whites. In some African populations, multiple births account for 60 out of every 1000. In Japan, where twins are very rare, they are viewed suspiciously as the products of a “litter,” more akin to dogs than to humans.
Offspring of the different races gestate and mature according to different r-K strategies. Blacks are born earlier and smaller than whites, but are stronger and better coordinated. They can sit up and roll over sooner than whites, who can do so sooner than Asians. On average, blacks walk at age 11 months, whites at 12 months, and Asians at 13 months.
Although it is a specialized measure of development, permanent tooth eruption occurs sooner in Africans than in Europeans, and later in Asians. Among primates in general, there is near-perfect correlation between lateness of permanent tooth eruption and such things as length of life, brain size, years to maturity, and complexity of social organization.
Blacks reach sexual maturity sooner than whites, who reach it sooner than Asians. By age twelve, 19 percent of American black girls have fully developed breasts and pubic hair whereas only five percent of white girls do. Blacks, on average, have an earlier first menstruation than whites, and Asians menstruate later than whites. In the United States, the average white woman is two full years older than the average black woman when she first has sexual intercourse, and Asians start having intercourse even later than whites.
Professor Rushton has bravely taken on the delicate subject of genital size, which has received reluctant but official attention because of AIDS. International organizations that try to provide condoms to people all over the world have discovered that one size does not fit all. Blacks have larger penises than whites, who have larger penises than Asians. The length of the vagina also differs proportionately in each race. Black men produce more sperm than do whites, and Asian men produce the least.
In the United States, black married couples report the greatest frequency of sexual intercourse, and Asian married couples report the lowest frequency. AIDS, like other sexually transmitted disease, is most common among blacks, rarest among Asians.
In Africa, compared to Europe or Asia, it is common to have sexual relations with many partners and to expend less effort on child-rearing. Older brothers and sisters often look after smaller children. There are also huge racial and regional differences in the number of offspring produced. In the United States, the average woman produces 14 children, grand children and great-grand children; in Africa the figure is 258. This prodigious African reproductive effort takes place over a shorter life-span. Blacks do not live as long as whites who, in turn, do not live as long as Asians.
Here, clearly, are patterns of maturational and reproductive behavior that show a consistent r-K pattern. Quick maturity, early reproduction, numerous offspring, and shorter lives put blacks closer to the oyster end of the scale than whites, who are closer to it than Asians.
Differences in sexual activity, life-span, and number of children are usually attributed to “culture” or “environment,” but there is every reason to believe that they are at least partly genetic, just as size of sex organs or age of sexual maturity are almost entirely genetic. Life-span, for example, is clearly hereditary in part. The age at which an adopted child will die is more easily predicted from the life-spans of the biological parents than from those of the adoptive parents. Likewise, identical twins die, on average, only 37 months apart whereas fraternal twins die 78 months apart.
What about the other components of the human K-strategy, such as altruism, law-abidingness, and the other characteristics that make up distinctly human social organizations? To what extent are what we think of as personality — and the cultural institutions that reflect a population’s group personality — the products of heredity, and thus properly included in an analysis of r-K strategy? Prof. Rushton has exhaustively surveyed recent studies of heredity, which suggest a powerful genetic influence on virtually all aspects of human behavior.
|— r||Egg Production||K —|
|Age of first intercourse||Late||Intermediate||Early|
|Twinning per 100,000||4||8||16|
Genes vs. Environment
Some of the most startling and convincing data on the relative influences of genes vs. environment come from studies of identical twins who were separated at birth and reared apart. Identical twins come from a single egg that splits in two; the twins are genetically identical. Fraternal twins are produced by a double ovulation and are no more genetically alike than ordinary siblings. (Unlike fraternal twinning rates, there are no racial differences in the frequencies of identical twinning.)
The crucial finding is that identical twins reared apart are more like each other in virtually every way than are fraternal twins who were reared in the same household. From these similarities it is possible to estimate how much of the variation in personality traits is caused by genes and how much by environment.
The chart at the bottom of this page shows twin-study estimates of the genetic contribution to various attitudes. These estimates almost certainly undervalue heritability because the method used to calculate it assumes that all aspects of environment are arbitrary. In fact, to a very large degree, people influence their own environments according to traits that are at least partly genetic. Thus, even within the same family, an aggressive child elicits different responses from parents and playmates — and thus has a different environment — from a child who is placid and cooperative. Once they are independent of their parents, young people follow their genetic propensities even more freely by choosing entirely different environments.
The methodology of heritability estimates ignores this. Thus, much of the influence on personality traits that is due to “environment” undoubtedly reflects personal surroundings that differ primarily because people shape their surroundings to match their genetic predilections.
Intelligence, which is one of the most important, stable and most frequently measured traits, is also one of the most heritable. Variations in intelligence within a population appear to be 60 to 80 percent governed by heredity.
It is important to note that heritability estimates are for variations in IQ, not total IQ. Thus, for two brothers with IQs of 100 and 120, a genetic component of 60 percent (and an environmental component of 40 percent) does not imply that 40 IQ points of the 100-IQ brother’s intelligence are theoretically attributable to environment. It means only that 40 percent of the 20-point difference between the brothers — 8 IQ points — is theoretically governed by non-genetic factors.
Furthermore, no one is really sure how environment influences the remaining 40 to 20 percent that is presumably non-genetic. Non-genetic factors may well be grossly biological events like malnutrition, childhood diseases, and mishaps in the womb, rather than the household or educational differences that most people think of as environment. Such things as Head Start or special education appear to have very little lasting effect on IQ differences either between individuals or races.
For the different racial groups, Prof. Rushton has aggregated the results of a great many IQ studies to arrive at the following averages:
Whites — 100, Asians — 105, American blacks (who are about 25 percent white) — 85, African blacks — 70 to 75, Amerindians (including Central and Latin Americans with little or no European blood) — 89, Polynesians, Micronesians, Melanesians, and Maoris — 80 to 95.
Although Asians have a higher general intelligence than whites, the difference is mainly in visuo-spatial performance rather than verbal ability. This makes Asians good engineers and mathematicians, but they do not have a pronounced advantage in careers like law or language teaching. Not surprisingly, a 1980s survey of professions in the United States found that Chinese-Americans were over-represented in the sciences at a rate six times their proportion in the population. However, there were only one fourth as many Chinese-American lawyers as their numbers would suggest. Blacks were minimally represented in both fields.
Although it is common to criticize IQ tests precisely because they give disparate results by race, there are other, more obviously biological indicators of intelligence that cannot be accused of “cultural bias.” One that Prof. Rushton himself has studied in depth is brain size.
Larger heads (containing larger brains) are positively correlated with intelligence. This is true within families, with the sibling with the largest head likely to be the most intelligent. It is also true within races, with large-brained blacks or Asians likely to be more intelligent than their small-brained co-racialists.
As groups, whites and Asians have larger brains than blacks. At age seven, for example, black children are 16 percentile points taller than white children, but their head perimeter is eight percentile points smaller. Asians are likely to have larger brains than whites, though some indications of larger size appear only after correcting upward for the fact that Asians are smaller than whites. A small person with the same sized brain as a big person can be thought of as having a “larger” brain, because smaller bodies require less brain to maintain basal functions.
Whites probably have about 100 million fewer cerebral neurons, on average, than Asians and blacks have about 480 million fewer than whites. The black/Asian difference is especially significant because of differences in body size. Blacks with small brains in large bodies are at a serious intellectual disadvantage compared to Asians because a larger proportion of their already-smaller brains is probably occupied with basal functions and not available for conscious thought.
Yet another directly physiological assessment of intelligence is the type of reaction-time test pioneered by Prof. Arthur Jensen of Berkeley. These tests require people to make simple choices when a light goes on. Intelligence is correlated with both speed and consistency of reaction time, and Asians perform better than whites, who perform better than blacks.
Prof. Rushton cites several additional reasons to suspect that racial differences in intelligence are due to genetics rather than environment. One is something called regression towards the mean. Individuals who are at extreme points in a normal distribution of any trait are likely to have children not so extreme as themselves. Very tall people, for example, are likely to have taller-than-average children, but their children’s heights tend towards the average for the population. With respect to IQ, studies have repeatedly shown that black Americans regress towards a mean of 85 while whites regress towards a mean of 100.
Inbreeding depression scores are another persuasive indicator that racial differences are genetic. Children that result from unions of very close relatives often have unusually low scores on certain kinds of intelligence tests, indicating that the abilities measured by those tests are highly susceptible to genetic influence. As it happens, these measures of intelligence are the very ones that show the greatest black-white differences, which suggests that the intelligence gap is also genetic.
Other Personality Differences
High intelligence is not the only hallmark of K-strategy. Professor Rushton explains that the races with more K traits have more complex and cooperative social organizations, are more restrained and law abiding, and show more altruism. In terms of r-K strategy, altruism and social cooperation permit individuals to rear their young under more dependable and peaceful circumstances — which is a precondition for groups that have staked their survival on producing small numbers of large-brained but slow-maturing offspring.
For traits like altruism and aggression to be properly included in an r-K pattern, they must be shown to be, like intelligence, at least partly controlled by heredity and to differ from race to race. Research suggests that these traits are greatly influenced by heredity, and that they appear early in life. In one study, children who were rated as “aggressive” by their peers at age eight were rated the same way by a different set of peers 10 years later. By the time they were 19 years old, those in the “aggressive” group were three times more likely to have a police record than those who were not considered “aggressive.”
Identical twins are about twice as much alike in terms of altruism and aggression as fraternal twins. Studies in both Europe and Japan have confirmed that when a twin has been convicted of a crime, an identical co-twin is two to three times more likely also to have been convicted than is a fraternal co-twin.
Shyness and sociability also appear very early in children and endure through adulthood. Studies of identical twins reared apart have shown astonishing similarities not only in personality, but in careers, frequencies of marriage, style of dress, and individual mannerisms [please see AR cover story of August, 1993, for a broader discussion of twin studies].
Research also shows that predictions about criminal behavior in adopted children can be made more accurately from the behavior of biological parents rather than adoptive parents. Some time between the ages of 21 and 30, the adult personality is “set like plaster,” and environment seems to have little effect on it.
Prof. Rushton points out that most people marry and make friends with people who are genetically like themselves. They seek others who not only look but think like they do. Durability of marriage has been shown to be linked to genetic similarity of the partners — in intelligence, appearance, and in other personality traits that are to some extent under genetic control.
It is therefore not surprising that biological siblings have more similar friends than do adopted siblings. Likewise, young criminals — who appear to have a genetic propensity for crime — commonly make friends with other young people with the same propensity.
This clearly demonstrated human preference for associating with others who are similar has important implications for race relations. Even very young children are conscious of race and show racial preferences. Prof. Rushton writes that ethnocentrism and “racism” are probably natural mechanisms built into the human genotype.
Expressions of altruism also have important implications for race relations. In virtually all species, the closer two individuals are, genetically, the more likely they are to help each other. This makes evolutionary sense if genes are thought of as the basic units of evolution. Genes for altruism are likely to leave more copies of themselves in future generations if they produce a trait that causes individuals to help their close kin survive.
Ants and bees are especially altruistic — frequently dying in great numbers to protect the colony — because they have an unusual reproductive pattern that causes workers to share 75 percent of their genes. Squirrels and monkeys can detect genetic distance between themselves and others, and are more cooperative towards close relatives.
Male Rhesus monkeys are promiscuous and cannot be sure that the child of a mate is their own. However, they have some unknown way of recognizing their offspring, and are kinder to them than they are to unrelated youngsters. (Actual kinship has been confirmed through blood tests.)
Belding’s ground squirrels mate with multiple partners, and females have litters that contain both sisters and half sisters. Despite the fact that they share the same womb and the same nest, full sisters fight less often and help each other more often than half sisters.
Among humans, preschool children are 40 times more likely to be assaulted by a step parent — that is to say, a genetic stranger — than by a biological parent. In promiscuous societies in which fathers are not sure which children are their own, they put more effort into caring for their sisters’ children than for those of their wives. A sister’s child is always close kin, whereas a promiscuous wife’s child may not be kin at all.
Experiments in altruism confirm the obvious: People are more willing to help people like themselves. Similar appearance is a good indicator of genetic similarity, and Prof. Rushton observes that racial solidarity can be viewed as a kind of extended nepotism. He also argues that it is often fruitless to look for sociological or economic reasons for the racial conflicts found all around the world. Genetic similarity and the desire to preserve a common set of genes are more likely explanations.
The races differ consistently in the personality traits that can be classified according to r-K theory, just as they do in intelligence. Asians are more restrained, cooperative, and less aggressive than whites; whites are more restrained and less aggressive than blacks. These rankings are the same, whether subjects are assessed by personality tests or by their peers. From an early age, blacks are more impulsive and dominant than whites, and males boast and swagger more. Asians are least dominant and impulsive.
Differences in crime rates by race are too well established to bear repeating [please see AR cover story of June, 1994]. These differences are consistent across multi- and mono-racial societies. Nevertheless, stiff resistance to genetic explanations leads to environmental theories that are unintentionally funny. As Prof. Rushton notes, earlier in this century, all forms of deviance were so low in American Chinatowns — despite their poverty — that the ghetto was thought to protect people from crime. For blacks, isolation is routinely said to cause crime.
Although trendy talk of “self-esteem” suggests otherwise, blacks have higher opinions of themselves than whites, who have higher opinions of themselves than Asians. Asians are the most introverted and anxious; blacks are the least. Suicide figures reflect this: Whites kill themselves twice as frequently as blacks, and Asians kill themselves more often than whites. Self-consciousness and introspection seem to rise along with K characteristics.
Rates of mental instability show the opposite trend. Two hundred and forty out of every 100,000 blacks are in mental institutions whereas only 162 of every 100,000 whites are. Nor is this a function of poverty or wealth; blacks suffer from mental disorders, drug addiction, and alcoholism at higher rates than whites in all social classes. Asians, despite their introversion and anxiety, have the fewest mental problems.
Differences Within Races
Prof. Rushton points out that r-K theory can account for differences between individuals of the same race. That is to say, people of the same race tend to vary according to the same pattern that distinguishes the races. In both Europe and Africa, the following traits tend to go together: large families, short life-span, criminality, high levels of sexuality, loose family ties, frequency of twinning.
Mothers of fraternal twins are more likely than other mothers to have had early first periods, larger families, lower birth-weight children (even when they are singletons), more infant mortality, to have been promiscuous, and to have shorter lives. Prof. Rushton has found that in all societies, fraternal twins are more likely to be born into the lower than the upper classes.
A Swedish study determined that girls who have early first periods are more likely to cheat, be truant, and try marijuana than girls who have late first periods. In the United States, early maturation is correlated with promiscuity, illegitimate births, leaving school, crime, and other social problems. Early sexual maturity seems to be heritable, with daughters resembling their mothers.
If altruism is an important K trait, crime would be an extreme r trait. Across broad populations, crime is associated with behavior that almost perfectly describes how blacks differ from whites and whites differ from Asians: large families, illegitimacy, low intelligence, early sexual maturity, promiscuity, weak family ties, little investment in children, and a short life.
Prof. Rushton suggests that the entire complex of r-K trait differences is therefore largely under genetic control, and that it characterizes different social classes just as it does races. There is little question that the most physiological r-Ktraits are heavily influenced by heredity. Prof. Rushton makes the additional point that physiology is closely correlated with many other forms of behavior previously thought to be independent of heredity but now found to be greatly influenced by it. The result is a strong case for believing that the patterns of behavior that distinguish races as well as individuals are largely inherent, reflect a consistent r-K pattern, and are impervious to social “programs.”
Prof. Rushton takes the argument one provocative step further. In the current era of social mobility, in which most hereditary social privileges have disappeared, people succeed or fail in life very much according to their native abilities. The children of the rich are usually smart and talented because they inherit the qualities that made their parents rich.
However, as Prof. Rushton points out, a child’s IQ is a better predictor of his adult social status than is the social status of his parents. And, when the unintelligent children of the rich start descending the social scale, they take on the habits and values of their new class rather than keep the ones of the class into which they were born. Even the most K-oriented parents can have an r child, whose life increasingly reflects his genetic inclinations.
Prof. Rushton’s findings are a serious blow to contemporary egalitarian dogma. Unfortunately, the usual reaction to his work is simply to make wild accusations about his motives. In an article called “Professors of Hate,” the October 20th issue of Rolling Stone claims to have unmasked him as a vicious racist.
Of course, it is the haters of science and free inquiry who build societies that cannot but degenerate as ours has. Anyone who wants to understand the world as it, and to base policy on facts rather than on fantasies, cannot ignore this very important book.
Buy Race, Evolution, and Behavior here.
Estimated Heritabilities of Attitudes Toward:
Death Penalty — .51
Hot and Cold
Why did the different races develop different r-K strategies? Prof. Rushton’s view is similar to that of Richard Lynn of the University of Coleraine in Northern Ireland, who has written extensively on race. He suggests that racial differences were caused by evolution in different climates.
Although there is disagreement about when different races appeared, Prof. Rushton inclines towards the “single-origin” theory, according to which all humans evolved from relatively recent African ancestors. Homo sapiens probably diverged from the ancestral homo line about 200,000 years ago. DNA analysis shows that human genes closest to those of the apes are found in Africans, which suggests an African origin. Similar analysis suggests that the earliest humans were probably much like Central African pygmies or Kalahari bushmen.
The African/non-African split probably took place about 110,000 years ago, as early man migrated out of Africa, and the white/Asian split occurred perhaps 41,000 years ago. The newly-appeared races continued their development in northern environments that were much harsher than that of Africa and that exerted great evolutionary pressure. In cold climates, people must make clothes, build fires, store food for the winter, and build shelters.
Hunting is much more important in the north because cold-climate fruits and nuts are highly seasonal. Hunting is also more difficult, because there is less cover for hunters. Even today, hunter-gatherer societies use more different and more sophisticated tools the further north they are found. Big-game hunting also requires that groups of men work together and that they devise a system for sharing the meat. This requires much more cooperation than fruit gathering by individuals, which, in the tropics, can be done year-round.
Prof. Rushton concludes that Asians developed particularly high intelligence and especially good visuo-spatial abilities because the Northern Siberian environment in which they lived and hunted was especially harsh. Amerindians, who crossed the Bering Strait, are related to Asians, but after they entered the Americas they moved steadily southward and were not subject to the rigors that sharpened the Asian mind. Also, they found large mammals that had never been hunted before and could be easily killed. They probably exterminated the giant sloths and mammoths that once inhabited the Americas.
If climate and latitude are crucial for evolution, Eskimos should be the most advanced people on earth. Prof. Rushton explains that humans did not start living in the Arctic until relatively recently, so the harsh climate has not yet selected Eskimos as keenly for intelligence and cooperation as it has Asians and Europeans.