Kinship and altruism: A cross‐cultural experimental study

Abstract

Humans are characterized by an unusual level of prosociality. Despite this, considerable indirect evidence suggests that biological kinship plays an important role in altruistic behaviour. All previous reports of the influence of kin selection on human altruism have, however, used correlational (rather than experimental) designs, or imposed only a hypothetical or negligible time cost on participants. Since these research designs fail either to control for confounding variables or to meet the criteria required as a test of Hamilton's rule for kin selection (that the altruist pays a true cost), they fail to establish unequivocally whether kin selection plays a role. We show that individuals from two different cultures behave in accordance with Hamilton's rule by acting more altruistically (imposing a higher physical cost upon themselves) towards more closely related individuals. Three possible sources of confound were ruled out: generational effects, sexual attraction and reciprocity. Performance on the task however did not exhibit a perfect linear relationship with relatedness, which might reflect either the intrusion of other variables (e.g. cultural differences in the way kinship is costed) or that our behavioural measure is insufficiently sensitive to fine‐tuned differences in the way individuals view their social world. These findings provide the first unequivocal experimental evidence that kinship plays a role in moderating altruistic behaviour. Kinship thus represents a baseline against which individuals pitch other criteria (including reciprocity, prosociality, obligation and a moral sense) when deciding how to behave towards others.

Reciprocity, culture and human cooperation: previous insights and a new cross-cultural experiment

“…Cues of kinship also increase cooperation (Madsen et al 2007;Krupp et al 2008). 8 Herrmann & Thöni (in press) and Kocher et al (2008) replicated the Fischbacher et al (2001) study using the same parameters.…”

The grammar of anger: Mapping the computational architecture of a recalibrational emotion

“…Therefore, there must exist a system that perceives evolutionarily reliable, cues of kinship, (such as maternal-perinatal association and duration of childhood coresidency), and then upregulates the individual's WTR toward individuals the system has classified as close genetic relatives (Lieberman, Tooby, & Cosmides, 2007;Sznycer, De Smet, Billingsley, & Lieberman, 2016). This raised WTR causes the actor to place a greater weight on the welfare of their kin when making decisions about whether to help or harm them (see Madsen et al, 2007).…”

Rowers' high: behavioural synchrony is correlated with elevated pain thresholds

“…Physical exercise is known to stimulate the release of endogenous opioids (endorphins) (Howlett et al 1984;Seeger et al 1984;Harbach et al 2000;Madsen et al 2007;Boecker et al 2008). Psychologically, endorphin release is experienced as a mild opiate 'high', a corresponding feeling of well-being, and light analgesia (Belluzi & Stein 1977;Stephano et al 2000), reflecting the role that endorphins play as part of the pain control system.…”