Department of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel.
Department of Psychology, California State University, Fullerton, California, USA.
Dev Sci. 2018 Nov;21(6):e12665. doi: 10.1111/desc.12665. Epub 2018 Apr 6.
Several related and complementary theoretical frameworks have been proposed to explain the existence of prosocial behavior, despite its potential fitness cost to the individual. These include kin selection theory, proposing that organisms have a propensity to help those to whom they are genetically related, and reciprocity, referring to the benefit of being prosocial, depending on past and future mutual interactions. A useful paradigm to examine prosociality is to compare mean levels of this behavior between monozygotic (MZ) and dizygotic (DZ) twins. Here, we examined the performance of 883 6.5-year-old twins (139 MZ and 302 DZ same-sex 6.5-year-old full twin pairs) in the Differential Productivity Task. In this task, the twins' behaviors were observed under two conditions: working for themselves vs. working for their co-twin. There were no significant differences between the performances of MZ and DZ twins in the prosocial condition of the task. Correlations within the twin dyads were significantly higher in MZ than DZ twins in the self-interested condition. However, similar MZ and DZ correlations were found in the prosocial condition, supporting the role of reciprocity in twins' prosociality towards each other.
尽管亲社会行为可能对个体的适应度造成代价，但仍有几个相关且互补的理论框架被提出以解释亲社会行为的存在。这些理论包括亲属选择理论，该理论提出生物体有帮助与其有遗传关系的个体的倾向，以及互惠性，指的是亲社会行为的好处，取决于过去和未来的相互作用。一个有用的范式来检验亲社会性是比较同卵（MZ）和异卵（DZ）双胞胎之间这种行为的平均水平。在这里，我们研究了 883 对 6.5 岁双胞胎（139 对同性别 MZ 和 302 对 DZ 6.5 岁全双胞胎）在差异生产力任务中的表现。在这个任务中，双胞胎的行为在两种条件下被观察：为自己工作与为同胞工作。在任务的亲社会条件下，MZ 和 DZ 双胞胎之间的表现没有显著差异。在自私条件下，双胞胎内部的相关性在 MZ 中明显高于 DZ，而在亲社会条件下，MZ 和 DZ 的相关性相似，这支持了互惠性在双胞胎彼此之间的亲社会性中的作用。
