Inbreeding, Incest, And The Incest Taboo: The State of Knowledge at the Turn of the Century - Hardcover

Arthur P. Wolf; William H. Durham

Hardcover

ISBN 10: 080474596X ISBN 13: 9780804745963

Publisher: Stanford University Press, 2004

Synopsis

Is inbreeding harmful? Are human beings and other primates naturally inclined to mate with their closest relatives? Why is incest widely prohibited? Why does the scope of the prohibition vary from society to society? Why does incest occur despite the prohibition? What are the consequences? After one hundred years of intense argument, a broad consensus has emerged on the first two questions, but the debate over the others continues.

That there is a biological basis for the avoidance of inbreeding seems incontrovertible, but just how injurious inbreeding really is for successive generations remains an open question. Nor has there been any conclusion to the debate over Freud’s view that the incest taboo is necessary because humans are sexually attracted to their closest relatives―a claim countered by Westermarck's argument for the sexually inhibiting effects of early childhood association.

This book brings together contributions from the fields of genetics, behavioral biology, primatology, biological and social anthropology, philosophy, and psychiatry which reexamine these questions.

About this title

About the Author

Arthur P. Wolf is David and Lucile Packard Foundation Professor of Human Biology at Stanford University. William H. Durham is Bing Professor of Human Biology at Stanford University.

From the Back Cover

Is inbreeding harmful? Are human beings and other primates naturally inclined to mate with their closest relatives? Why is incest widely prohibited? Why does the scope of the prohibition vary from society to society? Why does incest occur despite the prohibition? What are the consequences? After one hundred years of intense argument, a broad consensus has emerged on the first two questions, but the debate over the others continues.
That there is a biological basis for the avoidance of inbreeding seems incontrovertible, but just how injurious inbreeding really is for successive generations remains an open question. Nor has there been any conclusion to the debate over Freud’s view that the incest taboo is necessary because humans are sexually attracted to their closest relatives—a claim countered by Westermarck's argument for the sexually inhibiting effects of early childhood association.
This book brings together contributions from the fields of genetics, behavioral biology, primatology, biological and social anthropology, philosophy, and psychiatry which reexamine these questions.

From the Inside Flap

Is inbreeding harmful? Are human beings and other primates naturally inclined to mate with their closest relatives? Why is incest widely prohibited? Why does the scope of the prohibition vary from society to society? Why does incest occur despite the prohibition? What are the consequences? After one hundred years of intense argument, a broad consensus has emerged on the first two questions, but the debate over the others continues.
That there is a biological basis for the avoidance of inbreeding seems incontrovertible, but just how injurious inbreeding really is for successive generations remains an open question. Nor has there been any conclusion to the debate over Freud’s view that the incest taboo is necessary because humans are sexually attracted to their closest relatives—a claim countered by Westermarck's argument for the sexually inhibiting effects of early childhood association.
This book brings together contributions from the fields of genetics, behavioral biology, primatology, biological and social anthropology, philosophy, and psychiatry which reexamine these questions.

Excerpt. © Reprinted by permission. All rights reserved.

Inbreeding, Incest, and the Incest Taboo

THE STATE OF KNOWLEDGE AT THE TURN OF THE CENTURY

STANFORD UNIVERSITY PRESS

Copyright © 2004 Board of Trustees of the Leland Stanford Junior University
All right reserved.
ISBN: 978-0-8047-4596-3

Contents

List of Tables and Figures...........................................................................................viiIntroduction ARTHUR P. WOLF.........................................................................................11. Inbreeding Avoidance and Incest Taboos PATRICK BATESON...........................................................242. Genetic Aspects of Inbreeding and Incest ALAN H. BITTLES.........................................................383. Inbreeding Avoidance in Primates ANNE PUSEY......................................................................614. Explaining the Westermarck Effect, or, What Did Natural Selection Select For? ARTHUR P. WOLF.....................765. Ancient Egyptian Sibling Marriage and the Westermarck Effect WALTER SCHEIDEL.....................................936. From Genes to Incest Taboos: The Crucial Step NEVEN SESARDIC.....................................................1097. Assessing the Gaps in Westermarck's Theory WILLIAM H. DURHAM.....................................................1218. Refining the Incest Taboo: With Considerable Help from Bronislaw Malinowski HILL GATES...........................1399. Evolutionary Thought and the Current Clinical Understanding of Incest MARK T. ERICKSON...........................16110. The Incest Taboo as Darwinian Natural Right LARRY ARNHART.......................................................190List of Contributors.................................................................................................219Index................................................................................................................221

Chapter One

Inbreeding Avoidance and Incest Taboos

Patrick Bateson

I have never much liked the way some of my colleagues in the biological sciences have applied terms such as rape or marriage to animals. I appreciate that this is sometimes done to lighten the normally dull language of scientific discourse. However, these terms have established usage in human institutions with all their associated rights and responsibilities of individuals and culturally transmitted rules on what people can and cannot do. Problems of communication between disciplines are compounded when, having found some descriptive similarities between animals and humans and having investigated the animal cases, biologists or their popularizers use the animal findings to "explain" human behavior. Such arguments rely on a succession of puns, which are usually unconscious, but which are especially unfunny to those social scientists who feel threatened by an apparent takeover bid of the biologists.

I believe that incest should be restricted to human social behavior where culturally transmitted proscriptions limit sexual contact and marriage with close kin (and others who might be deemed to be close kin). Inbreeding avoidance should be used for behavior that makes matings with close kin less probable in both humans and nonhuman animals. This separation then leaves open the question of whether these behaviors have evolved for similar reasons and whether the two phenomena have similar current functions.

This chapter briefly reviews the evidence that people unconsciously choose mates who are a bit different from those individuals who are familiar from early life but not too different. In a biological context this is often referred to as optimal outbreeding. Why did it evolve? The question invites examination of the concept of adaptation and the role of Darwinian evolution in generating such adaptations. Since evolution is thought to involve changes in genes, it is necessary to be clear about the role of genes in an individual's development. When development is considered, a quite different set of issues is raised. These need to be considered in relation to the formation of mating preferences. Finally, it is necessary to come to the heart of the matter: what relations, if any, can be found between the avoidance of inbreeding and incest taboos?

Optimal Outbreeding

The biological costs of inbreeding are evident enough in other animals. They are particularly obvious in birds. If a male bird is mated with his sister, and their offspring are mated together, and so on for several generations, the line of descendants usually dies out fairly quickly. This happens because some damaging genes are more likely to be expressed in inbred animals. Some potentially harmful genes are recessive and therefore harmless when they are paired with a dissimilar gene, but they become damaging in their effects when combined with an identical gene. They are more likely to be paired with an identical recessive gene as a result of inbreeding. The presence of such genes is a consequence of the mobility of the birds and the low probability that they will mate with a bird of the opposite sex that is genetically similar to them. Over time, the recessive genes have accumulated in the genome because they are normally suppressed by their dominant partner gene.

The genetic costs of inbreeding arising from the expression of damaging recessive genes are the ones that people usually worry about. However, recessive genes are less important in mammals than they are in birds because mammals generally move around less and may live in quite highly inbred groups. The most important biological cost of excessive inbreeding is that it negates the benefits of the genetic variation generated by sexual reproduction. If an animal inbreeds too much, it might as well make many copies of itself without the effort and trouble of courtship and mating.

On the other side, excessive outbreeding also has costs. For a start, excessive outbreeding disrupts the relation between parts of the body that need to be well adapted to each other. The point is illustrated by human teeth and jaws. The size and shape of teeth are strongly inherited characteristics. So too are jaw size and shape, as may be seen in the famous paintings of the Hapsburg family, scattered around the museums of the world. The Drer painting of the Holy Roman Emperor Maximilian I reveals the large Hapsburg jaw, which remained as pronounced in his great-great-great-grandson, Philip IV of Spain, shown in the painting by Velasquez. The potential problem arising from too much outbreeding is that the inheritance of teeth and jaw sizes are not correlated. A woman with small jaws and small teeth who had a child by a man with big jaws and big teeth lays down trouble for her grandchildren, some of whom may inherit small jaws and big teeth. In a world without dentists, ill-fitting teeth were probably a serious cause of mortality. This example of mismatching, which is one of many that may arise in the complex integration of the body, simply illustrates the more general cost of outbreeding too much.

Some of the evolutionary pressures on mate choice arose from too much inbreeding, on the one hand, and from too much outbreeding on the other. A preference for an individual somewhat like close kin will minimize the opposing ill effects of breeding with individuals who are genetically too different. A sexual preference for individuals who are a bit different from close kin strikes a balance between the biological costs of inbreeding and those of outbreeding.

The suggestion is that individuals had greatest reproductive success if they mated with a partner who was somewhat similar to themselves, but not too similar. The hypothesis has gathered considerable empirical support from studies of animals. Japanese quail, for example, prefer mates that are first or second cousins, when given a choice in laboratory experiments. If they have been reared with unrelated individuals, the quail prefer mates that are a bit different from these familiar individuals. In humans a great mass of data shows that freely chosen human spouses are more like each other than would be expected on a chance basis. Similarities are not only social and psychological but also found in measures of body dimensions such as length of earlobe.

Humans choose partners somewhat like themselves. At the same time, people prefer sexual partners who look slightly different from individuals with whom they have grown up. Faces are perceived as more attractive if some of the facial features are exaggerated by caricaturing the image so that it differs from the average. Most people are attracted to faces that are distinctive and depart from the average. When the faces of individuals who were perceived as being attractive were averaged, this composite was preferred over the average of all faces.

Natural experiments have been performed unwittingly on human beings. Famously, Israeli kibbutzniks grow up together like siblings and rarely marry each other. The most comprehensive evidence has come from Arthur Wolf's (1994) study of the marriage statistics from Taiwan in the late nineteenth and early twentieth century, when Taiwan was under Japanese control. The Japanese kept detailed records for the births, marriages, and deaths of everyone on the island. As in many other parts of China, marriages were arranged and occurred mainly and most interestingly in two forms. The major type of marriage was the conventional one in which the partners first met each other when adolescent. In the minor type of marriage, the wife-to-be was adopted as a young girl into the family of her future husband. In minor-type marriages, therefore, the partners grew up together like siblings. In this sense they were like the quail in the laboratory experiment, having been reared with an individual of the opposite sex to whom they were not genetically related. Later in life their sexual interest in their partner was assessed in terms of divorce, marital fidelity, and the number of children produced. By all these measures, the minor marriages were conspicuously less successful than the major marriages. Typically, the young couples who had grown up together from an early age, like brother and sister, were not much interested in each other sexually when the time came for their marriage to be consummated.

While a great deal is still unknown about sexual preferences in both animals and humans, the similarities are quite striking. The processes involved in preference of humans for slight novelty have been subject to Darwinian evolution. However, acceptance of this point has to be tempered by an awareness that mate choice is influenced by many qualities that are beyond the scope of this chapter.

Adaptation and Darwinism

Unconscious preferences for slight novelty are seen by biologists as being adaptive in the sense that they serve to enhance the reproductive success of the individual who acts on those preferences. Darwinism has generated much distrust in the social sciences because it seemed to spawn such strange and, indeed, wicked social theories. The reason why biologists like me are still greatly enamored of the Grand Old Man is because he provided what is probably the only coherent and systematic explanation for adaptation-the match between the characteristics of organisms and the worlds in which they live.

Complicated things found in biology have the appearance of having been designed for a purpose. In the early nineteenth century a famous theologian, William Paley, put it this way: "It is the suitableness of these parts to one another; first, in the succession and order in which they act; and, secondly, with a view to the effect finally produced." Paley took this as proof of the existence of God. Darwin provided us with an explanation of how it came about. When individual differences are inherited, those individuals that are better adapted than others are more likely to survive and reproduce and then have offspring that share their adaptations.

The perception that behavior is designed springs from the relations between the behavior, the circumstances in which it is expressed, and the resulting consequences. The closeness of the perceived match between the tool and the job for which it is required is relative. In human design, the best that one person can do will be exceeded by somebody with superior technology. If you were on a picnic with a bottle of wine but no corkscrew, one of your companions might use a strong stick to push the cork into the bottle. If you had never seen this done before, you might be impressed by the selection of a rigid tool small enough to get inside the neck of the bottle. The tool would be an adaptation of a kind. Tools that are better adapted to the job of removing corks from wine bottles are available, of course, and an astonishing array of devices have been invented. One ingenious solution involved a pump and a hollow needle with a hole near the pointed end; the needle was pushed through the cork and air was pumped into the bottle, forcing the cork out. Sometimes, however, the bottle exploded and this tool quickly became extinct. As with human tools, what is perceived as good biological design may be superseded by an even better design, or the same solution may be achieved in different ways.

Among those who spin stories about biological design, a favorite figure of fun is an American artist, Gerald Thayer. He argued that the purpose of the plumage of all birds is to make detection by enemies difficult. Some of the undoubtedly beautiful illustrations were convincing examples of the principles of camouflage. However, among other celebrated examples, such as pink flamingos concealed in front of the pink evening sky, was a painting of a peacock with its resplendent tail stretched flat and matching the surrounding leaves and grass. The function of the tail was to make the bird difficult to see! Ludicrous attributions of function to biological structures and behavior have been likened to Rudyard Kipling's Just-So stories of how, for example, the leopard got his spots. However, the teasing is not wholly justified. Stories about current function are not about how the leopard got his spots, but what the spots do for the leopard now. That question is testable by observation and experiment.

Not every speculation about the current use of a behavior pattern is equally acceptable. Both logic and factual knowledge can be used to decide between competing claims. Superficially attractive ideas are quickly discarded when the animal is studied in its natural environment. The peacock raises his enormous tail in the presence of females, and he molts the cumbersome feathers as soon as the spring breeding season ends. If Thayer had been correct about the tail feathers being used as camouflage, the peacock should never raise them conspicuously and he should keep them year round.

Genes and Development

A Darwinian account tells us nothing about how those sexual preferences develop in the individual. It is true that for the Darwinian evolutionary mechanism to work, something must be inherited. But even if a single gene provides the basis for the distinctive beneficial character of the individual, a single gene is not sufficient for the development of the character. This is where we get to the heart of a very lively debate in biology.

Scientists collaborating on the Human Genome Project have elucidated nearly all the DNA sequences of all the genes on all twenty-three pairs of chromosomes found in every human cell. It is a staggering achievement. But the excitement about what is being done should be greatly moderated. "The Book of Life," as one leading scientist called it, will not provide the complete story about human nature.

The human genome is like a cook's larder list. Working out all the dishes that cooks might make from the ingredients available to them is another matter. If you want to understand what happens in the lifelong process from conception to death, you must study the process. The starting points of development include the genes. But they also include factors external to the genome, and of course, the social and physical conditions in which the individual grows up are crucial.

The language of a gene "for" a particular characteristic is exceedingly muddling to the nonscientist-and, if the truth be told, to many scientists as well. What the scientists mean (or should mean) is that a genetic difference between two groups is associated with a difference in a characteristic. They know perfectly well that other things are important and that, even in constant environmental conditions, the outcome depends on a combination of many genes. Particular combinations of genes have particular effects, and a gene that fits into one combination may not fit into another. Unfortunately, the language of a gene "for" a characteristic has a way of seducing the scientists themselves into believing their own sound bites. The language rests on a profound misunderstanding.

While genes obviously matter, even a cursory glance at humanity reveals the enormous importance of each person's experience, upbringing, and culture. Nobody could seriously doubt the remarkable human capacity for learning from personal experience and from others. It is obvious that experience, education, and culture make a big difference, whatever an individual's genetic inheritance. Individuals are not like the dry Japanese paper flowers that are simply put into water to open out.

The notion that genes are simply blueprints for an individual human is hopelessly misleading. In a blueprint, the mapping works both ways: starting from a finished house, the room can be found on the blueprint, just as the room's position is determined by the blueprint during the building process. This straightforward mapping is not true for genes and individual human behavior patterns, in either direction.

(Continues...)

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Edition details

• Publisher: Stanford University Press
• Publication date: 2004
• ISBN 10: 080474596X
• ISBN 13: 9780804745963
• Binding: Hardcover
• Language: English
• Edition number: 1
• Number of pages: 240