crowd of participants in speed-dating

Funny How? Humour as an Evolved Trait

– by Henry Wainwright

Humour is an everyday part of our lives and is present in virtually all human cultures, seemingly both past and present; the oldest known surviving joke being from Bronze Age Sumer, circa 1900 B.C. And while what we find funny is likely culturally and socially influenced, the fact that we all have a sense of humour, irrespective of culture, strongly suggests that humour evolved for some purpose.

One among many evolutionary explanations is that humour may have helped our ancestors to attract a mate. Indeed, individuals today consistently report a preference for humour in a romantic partner. However, it remains unclear why, in an ultimate sense, humour is considered an attractive quality. Humour is enjoyable, of course – but there is nothing inherently enjoyable or attractive about what we describe as funny. The question becomes, why did we evolve to find certain things funny and to be attracted to funny individuals?

The ‘fitness indicator hypothesis’ argues that humour aided ancestral courtship because being funny signals underlying genetic quality. Specifically, the idea is that funniness requires mental performance (e.g. speed, intelligence, creativity), which in turn requires a high-functioning brain, which in turn requires a low load of genetic mutations. Therefore, both being funny and being attracted to funny people are evolutionarily favoured because offspring of these couplings will inherit lower mutation loads and pass on their parents’ genes more effectively.

We tested predictions from the fitness indicator hypothesis by having participants – undergraduate students from the University of Queensland – report their preferences for humour in a romantic partner (i.e. their stated preferences) before engaging in a multiple unscripted, three-minute speed dates with each other, for a total of 860 unique dates. After each date, participants rated their partner on several characteristics including their funniness, their  humour receptivity (they found me funny), and their overall attractiveness.

Audio from these interactions were also surreptitiously recorded for a subset of 563 dates, which enabled the use of an additional, objective measure of humour, in the form of laughter frequency. From there we tested the central predictions of the fitness indicator hypothesis: that funniness and humour receptivity are attractive traits. We were also interested in additional predictions of the hypothesis, namely, that in accordance with parental investment theory, there should be a sex differences in how men and women respond to humour. That is, men should be attracted to humour receptivity in a partner more than women, whereas women, more so than men, should value funniness in a partner.

Indeed, results from stated preferences were largely consistent with these predicted sex differences. However, relying on stated preferences alone is problematic because doing so assumes that participants have sufficient, bias free insight into their own preferences. In practice, stated preferences often fail to predict individuals’ evaluations of potential partners (i.e. their revealed preferences). Therefore, we continued our investigation by looking at revealed preferences using laughter as well as ratings of humour .

We began by looking at how strongly participants’ ratings of their partners’ funniness or humour receptivity correlated with their ratings of the partners’ overall attractiveness. This allowed us to first check the basic premise of the fitness indicator hypothesis: that funniness is actually attractive. Consistent with this premise, partners who were rated as funnier were also rated as having greater overall attractiveness. Notably, the same was not found for humour receptivity – partners rated as more receptive were rated no more or less attractive overall. More damaging for the fitness indicator hypothesis, though, is that the predicted sex differences were not observed at all: the associations of both funniness and humour receptivity with overall attractiveness were similar in men and women.

Using ratings as a sole assessor of revealed preferences can be troublesome, as post-interaction ratings are possibly subject to a halo effect, whereby participants might rate a partner as funnier simply because they were more physically attractive, for instance. Therefore, we examined revealed preferences using laughter as a real-time, behavioural measure of both funniness and humour receptivity. After first establishing that at-partner-laughter (i.e. participant laughter following something their partner said) was positively associated with ratings of funniness, thus partially validating laughter as a measure of humour, we found that neither funniness nor humour receptivity, as measured by laughter, predicted ratings of overall attractiveness. Furthermore, using laughter, we found no evidence that men value humour receptivity in a speed-date partner more than women do, or that women value funniness in a speed-date partner more than men do.

In summary, we found that while stated preferences largely supported the sex differences predicted by the fitness indicator hypothesis, results from revealed preferences, which are taken as more valid than stated preferences, did not support these predicted sex differences and offered only mixed support for the central premise of the hypothesis, that funniness is attractive.

Overall, our results call into question not only the fitness indicator hypothesis, but also (or alternatively) the degree to which parental investment theory can be applied to sex differences in humans’ preferences for fitness indicators. The absence of significant sex differences in revealed preferences alone does not necessarily exclude humour as a fitness indicator; instead, it may be that the degree to which parental investment theory predicts sex differences in human fitness indicators has been overestimated. Humans exhibit mutual mate choice, and as a result, fitness indictors are still expected to evolve, but not necessarily with large (or any) sex differences. So the possibility remains that humour may be a fitness indicator, but men and women differ little, if at all, in their attraction to it. The current study is partially consistent with this possibility, as there is evidence that both funniness was a desirable trait to both sexes similarly. However, further investigation, especially into the role that humour plays in romantic attraction over longer periods of acquaintance, is needed to fully investigate this possibility, as well as to comprehensively test the fitness indicator hypothesis.

Read the original article: Wainwright, H.M., Zhao, A.A.Z., Sidari, M.J., Lee, A.J., Roberts, N., Makras, T., & Zietsch, B.P. (2024). Laughter and ratings of funniness in speed-dating do not support the fitness indicator hypothesis of humour. Evolution and Human Behavior, 45(1), 75-81.