Barron Andrew B, Hare Brian
Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia.
Department of Evolutionary Anthropology, Center for Cognitive Science, Duke University, Durham, NC, United States.
Front Psychol. 2020 Jan 16;10:2955. doi: 10.3389/fpsyg.2019.02955. eCollection 2019.
Human same-sex sexual attraction (SSSA) has long been considered to be an evolutionary puzzle. The trait is clearly biological: it is widespread and has a strong additive genetic basis, but how SSSA has evolved remains a subject of debate. Of itself, homosexual sexual behavior will not yield offspring, and consequently individuals expressing strong SSSA that are mostly or exclusively homosexual are presumed to have lower fitness and reproductive success. How then did the trait evolve, and how is it maintained in populations? Here we develop a novel argument for the evolution of SSSA that focuses on the likely adaptive social consequences of SSSA. We argue that same sex sexual attraction evolved as just one of a suite of traits responding to strong selection for ease of social integration or prosocial behavior. A strong driver of recent human behavioral evolution has been selection for reduced reactive aggression, increased social affiliation, social communication, and ease of social integration. In many prosocial mammals sex has adopted new social functions in contexts of social bonding, social reinforcement, appeasement, and play. We argue that for humans the social functions and benefits of sex apply to same-sex sexual behavior as well as heterosexual behavior. As a consequence we propose a degree of SSSA, was selected for in recent human evolution for its non-conceptive social benefits. We discuss how this hypothesis provides a better explanation for human sexual attractions and behavior than theories that invoke sexual inversion or single-locus genetic models.
长期以来，人类的同性性吸引一直被视为一个进化难题。这种特征显然是生物学上的：它广泛存在且具有强大的加性遗传基础，但同性性吸引是如何进化的仍然是一个有争议的话题。就其本身而言，同性恋性行为不会产生后代，因此，那些表现出强烈同性性吸引且大多或完全是同性恋的个体被认为具有较低的适应性和繁殖成功率。那么，这种特征是如何进化的，又是如何在种群中维持的呢？在这里，我们提出了一个关于同性性吸引进化的新观点，该观点聚焦于同性性吸引可能产生的适应性社会后果。我们认为，同性性吸引的进化只是一系列因强烈选择而产生的特征之一，这些选择旨在促进社会融合或亲社会行为。近期人类行为进化的一个强大驱动力是对减少反应性攻击、增加社会联系、社会沟通以及促进社会融合的选择。在许多亲社会哺乳动物中，性行为在社会联结、社会强化、安抚和玩耍等情境中具有了新的社会功能。我们认为，对人类来说，性行为的社会功能和益处同样适用于同性性行为和异性性行为。因此，我们提出，在近期人类进化过程中，一定程度的同性性吸引因其非生殖方面的社会益处而被选择。我们讨论了这一假设如何比那些援引性倒错或单基因座遗传模型的理论，能更好地解释人类的性吸引和性行为。
