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On Gene Pools, Language and Arranged Marriages

by Roger Bourke White, Jr., Copyright March 2004


Arranged marriage is one of the traits that separates mankind from the other animals. I can't think of another species where the parents of a species member -- rather than the species member him or herself -- select the mate.

This distinctive form of mate selection is made possible by mankind's extraordinary language ability. Only in humans does language have such power that parents can direct mating choices for their children.

What difference has this strong language ability and practice of arranged marriages made in the composition of the human gene pool? One of the major differences is that humans are more cooperative than they would be without arranged marriage.

Background: A Review of Genes and Natural Selection

Genes control the inherited traits of a living organism. Genes that carry desirable traits enhance the survivability of the organism's offspring. But what are desirable traits? Selection, natural or otherwise, is the process of deciding what desirable traits are. Selection drives the gene pool toward better genes.

Historic and near historic humans have learned to intervene in the selection process by doing selective breeding. Humans in historic times have intervened in the selection process in all domesticated plants and animals, and the resulting changes in morphology (the form and structure of an organism) have been spectacular. Every animal we farm and every plant that we cultivate looks and acts dramatically differently than its wild predecessor.

Humans have also practiced selective breeding on humans, but the rules used are different than those applied to plants and animals. In plants and animals, the producing of many useless offspring in an effort to get a single highly valued offspring is an acceptable cost, and this is the heart of improving a species though inbreeding. Among humans, inbreeding is universally shunned, except where the choice is between inbred offspring and no offspring at all. But while human societies will rarely employ inbreeding to improve the human species, they are all vigorous in observing who is healthy and who is desirable and vigorous in making breeding choices based on those traits.

The Limits to Selective Breeding

Humans can only intervene in those processes they can observe, so most inherited traits are decided without conscious human intervention because they are either invisible to human observation or too sophisticated for humans to calculate the effect of. For instance, until one hundred years ago, blood type was invisible to human observation so a bride or bridegroom couldn't be selected on the basis of blood type. Disease resistance is an example of a trait too sophisticated for human beings to control directly. Today we know a lot about the immune system, but there are still too many delicately balanced factors involved in the immune system for humans to select meaningfully between a good immune system and a great one.

The Apperance-Performance Tradeoff

Humans like to select mates based on their potential for good performance. But with so many unobservable factors influencing performance, that is hard to do directly. Instead humans rely on appearance as a substitute for performance.

Up to a point, good appearances are linked to good performance. A child who has a good physiology and has been raised in a healthy environment will tend to "look good" as a young adult. The young man who can run fast and hunt well has good "appearance" to those around him, and much of that appearance reflects good underlying physiology. But the link between performance and appearance is not tight, and it is easily possible to overdo appearance.

For instance, prominent eyes are a favorable attention-getting trait. This is desirable in women looking for a mate and children looking for food and attention. But eyeballs are designed to be round when they are being pressed on all sides by muscles and flesh. Prominently placed eyes will not work well for seeing if they are squeezed out of round by the lack of eyelid pressure on the front side. A person with eyes that are too prominent can't see well. This leads to a tradeoff -- is getting attention from other humans more important to survival, or is seeing well more important? This appearance-performance tradeoff is the heart of the old proverb, “Girls who wear glasses seldom get passes." It is just one example of a appearance-performance tradeoff.

When there is a tradeoff between appearance and performance, performance is suffering. The question selection, natural or otherwise, is constantly asking is: Are we at the optimum point in that tradeoff?

The answer is not static; it is enormously sensitive to the environment the organism is living in.

Secondary Sexual Characteristics

Secondary sexual characteristics are those sex-related traits that an organism develops that aren't related directly to developing eggs and sperm. Testes in a man are a primary sexual characteristic. Large size, beards, deep voices, and enjoying women-watching are secondary sexual characteristics. The link between secondary sexual characteristics and mate selection has been known since prehistoric times. The link is so strong that secondary sexual characteristics can become cumbersome and still be successful (an appearance-performance tradeoff). Consider the peacock's exaggerated plumage.

Mankind selects based on secondary sexual characteristics, just as animals do, but in the human species, there's an added wrinkle: The arranged marriage.

How Does Arranged Marriage Change the Selection Picture?
Sex Whom?

In most animal societies and in modern Western society, the male must be attractive to the female he will mate with and vice versa. In an arranged marriage society, the male must be attractive to the female's parents and vice versa.

Arranged marriage changes the criterion for attractiveness.

The Ideal Couple in an Arranged Marriage: Enhanced Cooperation

In arranged marriage societies, the appearance of the bride or groom doesn't determine the perfect arranged marriage -- the appearance of the extended families do. It's the collective success and failures of the couple's respective families that determine the desirability of the individual match-up. Rich families want to unite with other rich families; poor families want to marry into rich families.

With so many individuals involved in the mating choice (the extended family), what genes will make any difference? What genes will enhance survival? What genes will act as "good appearance genes" to prospective in-laws?

I don't know all the traits that have been affected, but one trait that has been enhanced by arranged marriage is cooperative behavior. Parents are going to be more sensitive to how cooperative a prospective son- or daughter-in-law is than their children are. Parents want a prospective in-law who will support the extended family, not one who is strong and resourceful, but "wild at heart”.

Language and the Arranged Marriage

The custom of arranged marriage is a direct consequence of language ability. It is "forceful" language that allows a parent to express an opinion on the desirability of a child's mate. If so, and if arranged marriage is a desirable trait because it allows for more improved breeding than direct mate selection does, then there should be a dramatic change in the drift of the gene pool as arranged marriage becomes established within a society. The gene pool would be drifting slowly in a particular direction before language and arranged marriage, then switch direction and speed as arranged marriage becomes widely established. If this is so, then gene pool drift may be a way to date the beginning of arranged marriage and the beginning of language.

As long as measuring gene pool drift directly is not available, then it may be that archeologists will be able to uncover artifacts that indicate elaborate marriage rituals. If so, the first appearance of these should coincide with the first appearance of arranged marriage and with the first appearance of communications skills strong enough that a father and mother can tell their sons and daughters who to marry (a language).

Arranged Marriages and High Technology

Advancing the general prosperity of humankind, from human-power-based economies to machine-based economies, seems to weaken the influence of the extended family, and this weakens the need for parents to intervene in their children's mate selection -- arranged marriages are not as influential in modern civilizations as they historically have been. Does this mean that humans are not being as selective about their mates as they historically have been?

I think not. What has replaced parental choice is two things: First, people in modern societies are getting older and much better educated before they marry, which means they are, in effect, becoming their own parents as far as mate selection is concerned. Second, we are now developing the technologies to examine genes much more closely than ever before. This means that parents actually have a lot more control than was ever historically possible.

I predict that the human gene pool is going to drift a hundred to a million times faster for the next few centuries as mankind continues to use all the tools at its disposal to make the best humans possible.

Arranged marriage was a tool for making better humans. It will be replaced by better tools, but the goal and the concept of having and raising the best children possible will be unchanged.

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