Virtue Signaling

by Geoffrey Miller

  This made a tidy story: Language didn’t evolve at all in any other species of human-like primate; it only evolved in our species 40,000 years ago; and it evolved to share knowledge within groups. Once it evolved, we quickly invented culture, civilization, and citation counts.

  The problem is that, in the light of new evidence, none of these arguments work anymore. If language evolved 40,000 years ago in Europe, how can we explain the fact that Africans and Australian aborigines can also speak – given the genetic evidence that they diverged from Europeans at least 40,000 years ago? Steven Pinker showed in The language instinct that language is a universal part of human nature, and since humans evolved at least 100,000 years ago in Africa, language must be at least that old. Paleontologists have also overturned Lieberman’s claims about mute Neanderthals. At most, the fossils suggest they might not have been able to produce the whole range of vowel sounds that modern humans do. That doesn’t mean they couldn’t speak.

  Most importantly, Richard Dawkins and John Krebs revolutionized the study of animal communication in 1978. They argued that it would be very odd for animals to evolve ways of giving away useful information to their evolutionary rivals. Communication in that sense would be altruistic, and it is very difficult for altruistic behaviors to evolve.

  Since the Dawkins/Krebs revolution, biologists have discovered that most signals that animals send to each other are not messages about the world, but messages about the signaller.

  Many animal signals simply reveal the signaller’s species, sex, age, or location. Others reveal the signaller’s needs, as when baby birds beg with open mouths to advertise their hunger to their parents. Most common of all, signals reveal the signaller’s fitness – their health, energy level, good brains, or good genes – to deter predators from chasing them, to deter rivals from fighting them, or to attract sexual partners who are seeking fit mates.

  Many animal signals, from bird song to whale song, from fruit-fly dances to the voltage surges from electric fish, say nothing more than “I’m here, I’m male, I’m healthy, copulate with me.” The signal’s form may be complex, but the signal’s message is vanishingly simple.

  Animals very rarely tell each other anything about the world. A few social insects such as bees inform their sisters about food sources; a few mammals warn their relatives about dangers from predators. Even these signals about food and predators are simple, stereotyped, and lazy: the bare minimum necessary to help the survival of their blood kin. Otherwise, most animals keep their knowledge, quite selfishly, to themselves.

  This makes human language look puzzling from a Darwinian viewpoint. Why do we bother to say anything remotely true, interesting, or relevant to anybody who is not closely related to us? In answering this question, we have to play by the evolutionary rules. We can’t just say language is for the good of the group or the species. No trait in any other species has even been shown to be for the benefit of unrelated group members. Nor can we say language just popped up because of a single big mutation – if speaking is altruistic, that mutation for speaking would have been eliminated very quickly by selection.

  The evidence from psychology, linguistics, and genetics shows that human language is a complex biological adaptation, and adaptations can only evolve gradually, over thousands of generations. They evolve because their evolutionary benefits consistently out-weigh their costs. The evolutionary cost for language was telling useful things to non-relatives, which would allow their genes to prosper at the expense of one’s own genes. But what were the survival or reproductive benefits of speaking?

  Most popular books on language ignore the altruism problem and don’t identify any specific evolutionary benefits of speaking. This is the weakness of Steven Pinker’s The language instinct , Jean Aitchison’s The seeds of speech , Derek Bickerton’s Language and human behavior , and Terence Deacon’s The symbolic species . This is also the weakness of so-called ‘ape language research.’ Chimps only learn visual symbols when human experimenters such as Sue Savage-Rumbaugh bribe them with food to do so. Where were the beneficent experimenters who rewarded our ancestors for speaking on the African savanna 200,000 years ago?

  Robin Dunbar developed one of the few theories that solves the altruism problem. In Grooming, gossip, and the evolution of language , he argued that language evolved as an extension of primate grooming behavior. Social primates maintain their relationships with other group members by grooming each other, up to several hours per day. Dunbar pointed out that as group sizes increased during human evolution, the time-costs of grooming would have increased to unsustainable levels. Perhaps language, especially social gossip, evolved as a more efficient way of servicing our relationships. The social benefits would have translated into both survival and reproductive payoffs – as good relationships do, in primate social groups.

  The trouble is, Dunbar’s theory doesn’t explain why language has content. Why couldn’t we have serviced our relationships by singing meaningless tunes to each other – like the ‘signature whistles’ of dolphins, or the ‘contact calls’ between primates? Dunbar jokes that his theory explains why most of our gossip seems so vacuous – “Nice weather”, “Did you see how much weight Geri lost?”, “Isn’t it a shame about those poor Californians running out of electricity?”. Yet, what we consider trite, any other species would consider astoundingly rich in meaning. If language is just verbal grooming, why is it about anything?

  To solve the altruism problem and to explain why language has content, I think we need to update a theory proposed by anthropologist Robbins Burling in 1986. Burling noted that men in every society get social status for their public speaking ability, and social status cashes out as reproductive success by attracting women. So, perhaps language evolved through sexual selection, just like bird song, with females favoring the best male orators. Bill gives good speeches, so Monica falls in love with him. He would have had extra babies under prehistoric conditions, and she would have benefited by merging her genes with his good-language genes to produce silver-tongued offspring. Thus, there would been runaway sexual selection for male language ability, and for female abilities to understand and judge language.

  One problem with Burling’s theory is that it doesn’t explain why women talk too. Most sexually-selected signals appear only in males, because in most species, males do all the courting and females do all the choosing. Female birds and whales don’t sing; why do women speak if language evolved through sexual selection?

  In The Mating Mind , I tried to understand why both sexes try to say interesting things during courtship. Unlike most other primates, humans form long-term sexual relationships, and mostly have babies within relationships (though there is plenty of infidelity). Since male humans invest more in their relationships and their children than any other primate, they have more incentives to be choosy about their long-term sexual partners. If our male ancestors favored verbally fluent females over inarticulate or boring females, then sexual selection would have shaped female language abilities as well as male language abilities.

  The mutuality of mate choice was crucial in giving us sexual equality in our adult language abilities.

  Burling’s theory also has the same trouble explaining content as Dunbar’s theory. I think this problem can be solved by thinking about what a big-brained species would want to advertise during sexual courtship. If intelligence is important for survival and social life, then it would be a good idea to choose sexual partners for their intelligence. Language makes a particularly good intelligence-indicator precisely because it has rich content. We put our thoughts and feelings into words – so when we talk to a potential mate, they can assess our thoughts and feelings.

  We can read each other’s minds through language, so we can choose mates for their minds, not just their bodies or songs. No other species can do this.

  Language evolved because our ancestors favored sexual partners who could show off what they knew, remembered, and imagined. The prehistoric Cyranos reproduce
d more successfully than the Homer Simpsons; likewise, the prehistoric Scheherezades. They didn’t always speak the truth about the world, but their language abilities always told the truth about themselves – the qualities of their minds and personalities that really matter when sustaining relationships and raising children together. Language isn’t used only for verbal courtship. Yet I suspect that the origin of language, like the origin of almost every other really complex animal signal, lies in the way that our ancestors fell in love.

  4. Sexual Selection for Moral Virtues

  ‘Virtue signaling’ seems simple at first glance, but there’s a lot more depth to it than just ‘people pretending to be better than they really are by showing off their consumer choices and political attitudes.’ To understand the depth, you have to go back in time, to the evolutionary origins of moral virtues themselves. Those origins aren’t obvious. It takes a bit of digging to get to their roots.

  This essay is my deepest dive into the origins of virtue, and it’s the intellectual heart of this book. It’s also the longest essay by far, the most systematic, and the most academic – although I tried hard to make the original paper accessible and vivid. If you understand sexual selection for moral virtues, you’ll understand the psychological foundations of virtue signaling, all the way from first dates through green consumerism to national politics.

  I wrote this paper in the run up to tenure, which I got in 2008. I needed a major theoretical paper in a top journal, so my colleagues would take me seriously as a big-picture thinker. I knew that Quarterly Review of Biology (QRB) would be more open to my evolutionary arguments than most psychology journals would be, so I wrote this for them, and was thrilled when they accepted it. QRB had published some ground-breaking papers on evolutionary models of altruism in the past that went on to become highly cited – notably ‘The evolution of reciprocal altruism’ by Robert Trivers, published in 1971, and cited over 12,000 times (which is a lot, by academic standards).

  I’d been interested in the origins of human kindness and altruism ever since grad school, and I’d written a bit about it in the ten years before this paper – including a whole chapter titled ‘Virtues of good breeding’ in my book The Mating Mind from 2000. But I’d never really put those arguments in a systematic, academically serious form until this paper. I tried to integrate everything I’d learned about evolutionary psychology, game theory, signaling theory, altruism, moral philosophy, and romance into this paper.

  The original paper had about 260 references. I tried to document all the paper’s empirical claims as best I could, given the research that was available around 2006 when I was writing this. For readability and brevity, I’ve stripped out the in-text citations and the bibliography. I’ve also stripped out the abstract, updated the formatting, and rephrased a few things. If you want the full, original, academic version, you can buy it from the QRB publisher here: https://www.journals.uchicago.edu/doi/full/10.1086/517857

  Originally published as:

  Miller, G. F. (2007). Sexual selection for moral virtues. Quarterly Review of Biology, 82(2), 97-125.

  ‘Human good turns out to be the activity of the soul exhibiting excellence.’ — Aristotle (Nichomachean Ethics , 350 B.C.)

  Among humans, attractive bodies may inspire short-term desire, but attractive moral traits can inspire long-term love. Is this a coincidence, or are there some functional similarities between sexual ornaments and moral virtues? Many sexually attractive bodily traits evolved to reveal phenotypic condition and genetic quality, including health, fertility, and longevity. This paper explores the possibility that some human moral traits evolved through sexual selection to serve an analogous display function. The most romantically attractive mental traits – kindness, bravery, honesty, integrity, and fidelity – often have a moral dimension.

  Recent empirical research suggests that many of these moral traits are sexually attractive, and can serve as mental fitness indicators: they are judged as reliably revealing good mental health, good brain efficiency, good genetic quality, and good capacity for sustaining cooperative sexual relationships and investing in children. Thus, the moral virtues that we consider sexually attractive are not culturally or evolutionarily arbitrary. Rather, they evolved to advertise one’s individual fitness (including genetic quality, parenting abilities, and relationship-coordination abilities) in hard-to-fake ways that can be understood through a combination of sexual selection theory and costly signaling theory.

  (‘Fitness’ here means adaptive design for reproductive success, or the statistical propensity to survive and reproduce successfully; it may not equal achieved reproductive success under evolutionarily novel conditions in the modern world, especially given contraception.)

  The hypothesis here is that sexual selection shaped at least some of our distinctively human moral virtues as reliable fitness indicators. Precursors of many human moral virtues, such as empathy, fairness, and peace-making, have been found in other great apes. My claim is not that sexual selection created our moral virtues from scratch in our species alone. Rather, sexual selection amplified our standard social-primate virtues into uniquely elaborated human forms.

  This mate choice model is intended to complement, not replace, other models of human moral evolution. Besides sexual selection, many other forms of social selection probably shaped human morality, including:

  kin selection

  reciprocal altruism

  discriminative parental solicitude

  commitment mechanisms

  risk-sharing mechanisms

  social norms and punishment mechanisms

  group selection

  equilibrium selection among alternative evolutionary strategies (more on that later).

  Each of these moral evolution models has led to valuable insights and progressive research traditions. Some are better at explaining moral virtues such as love of children, siblings, and parents, and righteous anger at cheats and promise-breakers. This morality-through-mate-choice model also has distinctive strengths and weaknesses that can explain some but not all moral virtues – especially those that show high sexual attractiveness, assortative mating, phenotypic and genetic variance, heritability, condition-dependent costs, conspicuous display in courtship settings, and young adult age-peaks in display.

  Yet for each of the traditional mechanisms above, sexual selection would tend to anticipate, sharpen, and amplify the social selection pressures to produce a more extreme, costly, pro-social version of the moral virtue than social selection could achieve alone. The reason is that non-sexual forms of social selection can shape morality only insofar as they confer fairly concrete survival benefits (such as shared food, protection from predators) on the morally virtuous. Mate choice can shape morality much more powerfully and broadly, because it demands only that moral behaviors carry some signaling value about a potential mate’s good genes and/or good parent/partner abilities.

  In general, sexual selection can ‘super-charge’ other evolutionary processes by adding just the sort of positive-feedback dynamics that tend to trigger evolutionary innovation and speciation. If a moral virtue becomes useful in kinship, reciprocity, or group prosperity, our ancestors probably did not ignore it when choosing mates.

  Some moral virtues may be attractive as signals (such as heroism as a signal of competence), whereas others may seem attractive as traits in their own right (such as fairness as an intrinsically valuable trait in a long-term sexual relationship). However, this distinction is tricky, because there is almost always scope for misrepresenting one’s traits during courtship. A potential mate may act agreeable and easy-going during courtship, then become irritable and cantankerous after a couple of years. In this case, courtship-agreeableness was valued as a signal of likely future relationship-agreeableness, but it proved an unreliable signal of the trait’s temporal stability. Sexual commitment often brings moral disappointment. The costly signaling perspective is helpful in identifying such pitfalls – not only situations where o
ne trait is unreliably correlated with another trait, but also situations where the present value of a trait is unreliably correlated with the future value of that same trait. From this viewpoint, all moral virtues displayed during sexual courtship are potentially fallible signals – of other traits or future traits – so their reliability and stability must be analyzed in a costly signaling framework.

  To suggest that human moral virtues evolved through mate choice is not to suggest that human morality is sexually motivated at the level of individual behavior. Evolutionary functions do not equal proximate motivations. Even if the evolutionary payoffs for moral behavior were mainly reproductive, moral behavior can arise at the proximate level from genuinely moral personalities and motives – not just copulatory motives. Indeed, sexual patience is a key virtue in courtship: if a potential male mate shows sexual self-restraint for a long time, this protects female mate choice, and signals that the male is not just looking for a short-term affair or extra-pair copulation.

  This paper argues that there is substantial overlap between sexually-attractive personality traits and human moral virtues, but does not pretend that all sexually attractive traits are virtues, or that all virtues are sexually attractive under all conditions. Some individuals may feel most aroused by potential mates who show Machiavellian cunning, aggressive ferocity, or rampant promiscuity. Human sexuality gets kinky sometimes, and nice guys don’t always win. To argue that some moral virtues evolved through mate choice is not to argue that vice is never attractive.

  Moral Virtues and Virtue Ethics

  This paper goes beyond my book The Mating Mind by reviewing relevant empirical and theoretical work since 2000, and by integrating relevant insights from individual differences research, behavior genetics, and moral philosophy. For example, it connects recent person perception research with person-level approaches to moral philosophy, especially virtue ethics and naturalistic approaches to understanding moral intuitions.