Collegium Helveticum, ETH Zürich, Schmelzbergstrasse 25, Zürich, 8092, Switzerland.
Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland.
Hum Nat. 2023 Sep;34(3):501-511. doi: 10.1007/s12110-023-09461-3. Epub 2023 Sep 22.
The amygdala is a hub in brain networks that supports social life and fear processing. Compared with other apes, humans have a relatively larger lateral nucleus of the amygdala, which is consistent with both the self-domestication and the cooperative breeding hypotheses of human evolution. Here, we take a comparative approach to the evolutionary origin of the relatively larger lateral amygdala nucleus in humans. We carry out phylogenetic analysis on a sample of 17 mammalian species for which we acquired single amygdala nuclei volumetric data. Our results indicate that there has been convergent evolution toward larger lateral amygdala nuclei in both domesticated and cooperatively breeding mammals. These results suggest that changes in processing fearful stimuli to reduce fear-induced aggression, which are necessary for domesticated and cooperatively breeding species alike, tap into the same neurobiological proximate mechanism. However, humans show changes not only in processing fearful stimuli but also in proactive prosociality. Since cooperative breeding, but not domestication, is also associated with increased proactive prosociality, a prominent role of the former during human evolution is more parsimonious, whereas self-domestication may have been involved as an additional stepping stone.
杏仁核是支持社交生活和恐惧处理的大脑网络枢纽。与其他猿类相比，人类的杏仁核外侧核相对较大，这与人类进化的自我驯化和合作繁殖假说一致。在这里，我们采用比较的方法来研究人类相对较大的杏仁核外侧核的进化起源。我们对 17 种哺乳动物的样本进行了系统发育分析，获得了单个杏仁核核体积数据。我们的研究结果表明，无论是在驯化动物还是合作繁殖动物中，都存在着杏仁核外侧核向更大体积进化的趋同进化。这些结果表明，减少恐惧引起的攻击的恐惧刺激处理的变化，对于驯化和合作繁殖的物种都是必要的，它们利用了相同的神经生物学近因机制。然而，人类不仅在处理恐惧刺激方面发生了变化，而且在积极的亲社会行为方面也发生了变化。由于合作繁殖，而不是驯化，与积极的亲社会行为的增加有关，因此，前者在人类进化中的作用更为合理，而自我驯化可能是一个额外的踏脚石。
