Surprise, surprise: An evolutionary psychology study finds that men under the observation of female researchers are more generous with money than men under the observation of male researchers.
This show-off hypothesis of male generosity is consistent with field data. For instance, among hunter-gatherer societies, men who regularly provide large animal meat have more sexual partners (Hawkes, 1993; Hawkes and Bliege Bird, 2002). It has been suggested, that in restaurants, groups of men leave much better tips for waitresses than groups of women and men on dates with women leave especially good tips (Miller, 2000). When in the presence of a female, men also donate more money to panhandlers (Goldberg, 1995), and act heroically to help strangers in emergencies (Griskevicius et al., 2007; Latané, 1970). Finally, recent data from wild chimpanzee populations suggest that males use food-sharing to show-off to sexually receptive females (Hockings et al., 2007).
The show-off hypothesis hasn’t been tested before under strict, controlled conditions with humans. Nonetheless, the findings of this study indicate that human male generosity is a trait signal (learn more about costly signaling theory) used to display reproductive fitness.
For this research, male and female students were observed by two confederates (one attractive female, one attractive male) playing the role of researchers. The experimenter did not tell participants why the observer was present – only that both members would be debriefed after the participant completed playing a series of experimental games. Additionally, participants were asked to refrain from interacting with the observer.
- Variable 1: observed by the same sex
- Variable 2: observed by the opposite sex
- Control: no observer present
All participants were asked what percentage of earned money (earned through playing the games, up to 50$ could be earned) they would be willing to donate to charity at the end of the experimental games. The researchers predicted that only male students being observed by the attractive female confederate would increase their donation percentage.
After making their donation, in the observer conditions the on screen computer instructions told the observer to leave the room. Participants were then asked several questions in private. In observer conditions questions included rating the sexual attractiveness of their observer and their self-rated attractiveness on a scale from 1-7 (1 = not attractive at all; 7 = extremely attractive). In addition, participants were asked to state their sexual orientation. Finally, they were debriefed and dismissed. At the end of the study six people selected at random received the money that they earned throughout the experimental games minus the charity donation; these charity donations were given to the NSPCC.
Only men contributed significantly more money to donation under the female observer condition, compared to the male observer and no observer conditions. Donations from female participants did not significantly differ between all three conditions.
The researchers found a positive correlation between male participant generosity and perceived sexual attractiveness of the female observer. Additionally, participants (both male and female) who rated their attractiveness as average or below were significantly more charitable than participants who rated their attractiveness as high. The researchers’ study suggests that male altruism is a strategic mating signal used to advertise positive reproductive traits to females. They also suspect an inverse correlation between self-perceived attractiveness and altruistic trait signaling.