Objectives Pre-historic decline in human craniofacial masculinity has been proposed as evidence of selection against reactive aggression and a process of ‘human self-domestication’ thought to have promoted complex capacities including language, culture, and cumulative technological development. This follows observations of similar morphological changes in non-human animals under selection for reduced aggression. Two distinct domestication hypotheses posit developmental explanations; involving dampened migration of embryonic neural crest cells (NCCs), and declining androgen influences, respectively. Here, I assess the operation and potential interaction of these two mechanisms and consider their role in human adaptation to a cooperative sociocultural niche. Methods I provide a review and synthesis of related literature with a focus on physiological mechanisms affecting domesticated reductions in masculinity and sexual dimorphism. Further, I examine several modes of pre-historic sociosexual selection against aggressive reactivity which are proposed to have driven human self-domestication. Results I show that pluripotent NCCs provide progenitors for a wide range of vertebrate masculine features, acting as regular targets for sexually driven evolutionary change. This suggests hypoplasia of NCC-derived tissues due to dampened NCC migration is sufficient to explain declines in lineage specific masculine traits and features under domestication. However, lineage-specific androgen receptor variability likely moderates hypoplasia in NCC-derived tissues, and may influence NCC migration, though this latter influence requires further investigation. Conclusions These findings synthesise and extend theorised physiological mechanisms of domestication and human self-domestication. Self-domestication under sociosexual selection for dampened reactive aggression and correlated masculine physiology enabled human adaptation to an increasingly complex sociocultural niche. The analysis highlights several avenues for further productive investigation.

中文翻译：

---

阳刚之气和人类自我驯化的机制

目的有人提出史前人类颅面阳刚之气的下降是选择对抗反应性侵略的证据，并且认为“人类自我驯化”的过程促进了包括语言，文化和累积技术发展在内的复杂能力。这是由于观察到在选择减少侵略性的非人类动物中有类似的形态变化。两种不同的归化假设提出了发展解释。分别涉及抑制胚胎神经cells细胞（NCC）的迁移和减少雄激素的影响。在这里，我评估了这两种机制的运作和潜在的相互作用，并考虑了它们在人类适应合作性社会文化环境中的作用。方法我提供了相关文献的综述和综述，重点关注影响男性化和性二态化驯化减少的生理机制。此外，我研究了针对侵略性反应的史前社会性别选择的几种模式，这些模式被认为已经推动了人类的自我驯化。结果我表明，多能NCC为广泛的脊椎动物男性特征提供了祖细胞，它们是性驱动进化变化的常规靶标。这表明由于NCC迁移受阻而导致的NCC衍生组织发育不全足以解释在驯化下血统特定男性特征和特征的下降。但是，沿袭特异性雄激素受体的变异性可能会减轻NCC衍生组织的发育不全，并可能影响NCC迁移，尽管后一种影响需要进一步调查。结论这些发现综合并扩展了驯化和人类自我驯化的理论生理机制。在社会性别选择下进行自我驯化以减轻反应性攻击和相关的男性生理行为，使人类能够适应日益复杂的社会文化环境。分析强调了进一步进行生产调查的几种途径。