Re: Mating Mind

From: Robin Hanson (
Date: Sun Jul 02 2000 - 10:17:52 MDT

My web site seems to be down for the weekend (university systems folks
seem to be away for the weekend so they aren't fixing their network.)

So here is the current version of :

Is Fairness About Clear Fitness Signals?

Is Fairness About Clear Fitness Signals?

by Robin Hanson
July 1, 2000

"Fairness" is often described in terms of equality of outcomes. But in a game, the "fairest" rules are those that make the ablest players mostly likely to win, instead of those that distribute wins the most evenly among players.

More generally, a wide range of otherwise puzzling common intuitions about fairness can be understood if the fundamental "game" of life is seen as wooing, i.e., attracting mates by showing that you have the fittest genes. The fairest social institutions would then be those in which success correlates as much as possible with genetic fitness.

It can thus seem fair that the most attractive witty athletic folks get more mates and money, but seem unfair that the rich can buy better education for their children. Makeup can seem fair, while breast implants seem unfair. This theory has many implications about the kinds of redistribution and genetic policies that will seem fair.


People have many intuitions about what actions and outcomes they consider "fair," intuitions which effect their behavior in many ways. For example, a thriving literature in experimental economics has tried to explain behavior in simple bargaining games via desires for relatively equal outcomes, at least among those who "play fair." Evolutionary psychologists have plausibly explained some of this behavior via "reciprocal altruism", or evolved tendencies to help those who help us. And large literatures in moral philosophy and elsewhere have explored the many things that people would want if they had various kinds of egalitarian desires.

A wide range of common intuitions about "fairness" cannot, however, be easily understood in terms of desires for relatively equal outcomes. For example, while there is widespread political support for redistributing wealth from the rich to the poor, and for limiting the influence of money on many areas of life, there is very little support for redistributing from the pretty to the ugly, or from the witty to the dull. And there is little support for limiting the advantages that good-looking people receive in most areas of life.

In this short paper I describe how many of these common intuitions about intuitions can be understood a desire for clear fitness signals. That is, people use looks, sport, art, conversation, education, wealth, and much more to signal to potential mates that they have good genes. And people seem to think social institutions are "fairer" when they result in a stronger correlation between mating signals and fitness. It is as if the game of life is mating, and this game is fair when there is a "level paying field" which makes the the best players the most likely to win.

We first review the many common intutions about fairness that can not be easily understood as a desire for equal outcomes, we then discuss how these can be understood in terms of a preference for clear mating signals, and we conclude with a short discussion of some implications of this theory for what future policies will be considered fair.

Fairness Intuitions

Simple egalitarian desires do not easily account for many of the diverse intutions ordinary people hold regarding fairness. Nor do more sophsticated conceptions such as primarily wanting equality, but accepting inequality that comes from giving people incentives to be productive.

Consider these many examples of (my best guesses about) typical perceptions about which actions or outcomes are fair or unfair. (Some of these intuitions may well be specific to our culture; it would be nice to have survey data to test these guesses).

Explaining Fairness As Clear Fitness Signals

Many animals use features such as body size and symmetry to signal their abilities to potential mates [Zahavi]. In "The Mating Mind", Geoffrey Miller argues that most the behaviors that make humans unique, including sport, art, morality, and language, also evolved primarily as costly signals to potential mates about the fitness of our genes [Miller]. Success in each of these areas, such as sport or art, shows a broad average quality of a somewhat different aspect of our genome.

Perhaps we can make sense of the diverse set of apparently non-egalitarian fairness intuitions if we postulate that people typically want mating signals to indicate overall genetic fitness as clearly as possible. If this is what people want, they should like having many "success" signals to look at, but worry that "cross-talk" from noisy signals may degrade signals we think are clearer. Non-genetic influences on success would also be worrisome, except when such influences are known and uniform, and can hence be corrected for in our inferences.

Improving the clarity of a signal would hurt some signalers and benefit others. But the audience for such signals seems to have more of a common cause in wanting clearer signals, plausibly making for a net majority in favor of clearer signals.

These implications of a signal-clarity theory of fairness seem to be in rough correspondence with many of the non-egalitarian fairness intuitions described above.

Under this concept of fairness, makeup is fair if it helps make it easier to tell symmetric faces from asymmetric ones, but breast implants and hair growth drugs are unfair if they reduce the correlation between your genes and how you look. Sports are more fair and interesting when doing well depends on broad measures of physical ability, rather than on narrower measures such as your body's ability to tolerate steroids. And since fine ability distinctions are most easily seen when people play others of similar ability, it is unfair to play against someone you could too obviously beat.

It should seem all right if success in music, politics, or even academia depends in part on other clear signals of broad genetic quality, such as wit or good looks, since those are easy to observe and correct for, and since the main point is to sort people by overall genetic fitness. It is more of a problem, however, if such success depends on wealth, especially the wealth of one's parents, since we expect a lot of noise in the relation between genes and wealth. We also expect that parents and "who you know" are a noisy measure of genes, so we are often similarly uncomfortable when success depends on these.

We should prefer that people who are more able and who work harder receive more money, since that gives us yet another signal about people's genes. We just do not want that noisy signal to mess up other clearer signals. We do not like people going out of their way to make wealth depending on random things, so we do not like gambling. But we don't mind if wages depend on other fitness signals like education, even when education isn't much related to job performance.

We should not mind much if success depends on easily observable factors like age, ethnicity, or gender, as long as we are all clear how success depends on these things. But we should be concerned that this dependence be known and uniform; it should seem unfair if some people discriminate more than others against some ethnicity, for example. And trying to eliminate such discrimination is one simple way to try to make it known and uniform.

If we still see sports, art, and conversation as primarily ways for ordinary people to show their superior genes, then we should prefer large variations in such outcomes, because that allows us to better discriminate between potential mates. So we can accept a few people making most of the money in sports or art. But for activities, like getting food and shelter, which we see as important for non-signaling reasons, we are more concerned about inequality.

Our ancestors often shared the gains from high-variance hunting, but publicly claimed personal credit for their hunting success in the process. This allowed high variance in signals but lower variance in food intake, which seems the best of both worlds. Similarly, modern workers can accept high taxes that reduce wealth variance without greatly changing relative rankings or the ability to distinguish small differences in rankings.

Since charity is primarily a signal of wealth, it seems fair to praise the rich more, and to not care so much about the effectiveness of their gifts. If those who receive charity get a public stigma, then we can correct for such gifts in inferring their ability from their wealth.

Policy Implications

If correct, this theory has some implications for the kinds of policies that people will accept as "fair." We can foresee implications for egalitarian redistribution, and for genetic privacy and modifications. Of course fairness isn't everything, since people may often be willing to trade it for other things, and so even knowing which policies will seem how fair does not by itself tell us which policies will be implemented.

Regarding redistribution, the signal-clarity concept of fairness can accept large tax rates, but not if taxes are too complex and arbitrary, redistributing in difficult to untangle ways unrelated to genetic fitness. That would just add undesirable noise into wealth as a signal of fitness. This fairness concept also suggests, however, that there is almost no prospect of redistribution of mating success itself. People should insist that they remain free to choose mates, even if that makes some people get much more or better mates than others.

People should be comfortable with "raising the valleys" in sport, art, and looks, via improving the success of those who do worse, as long as overall rankings remain clear. If people mainly care about relative success, however, this may not raise welfare much. People should be less comfortable with direct monetary redistribution from the genetically rich to the genetically poor, as that would make it harder to infer fitness from wealth.

Regarding genetic policies, people may be more comfortable than many expect about direct genetic discrimination, such as depicted in the movie GATTACA. If medical genetic tests can determine overall genetic fitness with high reliability, people may well accept using such tests to determine success in education, jobs, politics and elsewhere. If, however, available medical tests are narrow, looking only at some small subset of the genome, or they correlate poorly with evolved signals that we consider to have high reliability, then we may fear over-reliance on narrow medical tests will induce too much noise into evaluations of overall fitness.

People may also be more comfortable than many expect about a loss of genetic privacy, similar to the way consumers have been less concerned about other forms of privacy than many observers expected. There might be concerns, however, about excessive reliance on too narrow a measure of genetic fitness.

It is difficult to foresee how "fair" it will seem to let people buy better genes with money. If our genes could reason abstractly, they would realize that such purchases should strengthen, not weaken, the correlation between mating signals and genetic fitness. But such purchases were not possible when our genes gave our ancestors the concepts of fairness that we have inherited. So it may be the intuitions our genes gave us will consider such purchases as unfair, seeing them as similar to breast implants that buy looks that are poorly related to the genes your parents gave you.


Many aspects of intuitions about fairness in personal interactions have something to do with equality of outcomes, and many have inferred from this that fairness is mostly about equality of outcomes. Using such conceptions, such people have advocated policies which better equalize outcomes between the pretty and the ugly, the witty and the dull, and so on. While there seems to be little political support for such policies now, advocates may presume this is primarily because people haven't realized the implications of their fairness intuitions.

Ordinary intuitions about fairness may, however, be more about a "level playing field" for mating games than about equality of outcomes. People may accept redistributive policies that do not substantially interfere with fitness signals, such as uniform wealth taxes, and may want to reduce the "cross-talk" between noisy and clearer signals, such as between wealth and education. But this doesn't mean that they primarily want equal outcomes. So egalitarian notions of fairness may misled us about the policies that people will consider fair.

Of course nothing has been said so far about whether common intuitions of fairness are "good" or "just" And in fact, a better understanding of the self-serving genetic origins of our fairness intuitions may well led us to stronger doubts about their normative appropriateness. Such understanding may also, however, induce more doubts about how easy it would be to gain political support for normatively "better" policies that are contrary to common intuitions about fairness.

For their comments, I thank Chris Auld, Bryan Caplan, Tyler Cowen, Hal Finney, Peggy Jackson, and Rob Nelson.

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