Kessler Sharon E, Bonnell Tyler R, Byrne Richard W, Chapman Colin A
Department of Anthropology, McGill University, Canada; Durham University, Department of Anthropology, UK.
Department of Psychology, University of Lethbridge, Canada.
J Hum Evol. 2017 Jul;108:92-109. doi: 10.1016/j.jhevol.2017.02.009. Epub 2017 May 17.
The emergence of providing care to diseased conspecifics must have been a turning point during the evolution of hominin sociality. On a population level, care may have minimized the costs of socially transmitted diseases at a time of increasing social complexity, although individual care-givers probably incurred increased transmission risks. We propose that care-giving likely originated within kin networks, where the costs may have been balanced by fitness increases obtained through caring for ill kin. We test a novel hypothesis of hominin cognitive evolution in which disease may have selected for the cognitive ability to recognize when a conspecific is infected. Because diseases may produce symptoms that are likely detectable via the perceptual-cognitive pathways integral to social cognition, we suggest that disease recognition and social cognition may have evolved together. Using agent-based modeling, we test 1) under what conditions disease can select for increasing disease recognition and care-giving among kin, 2) whether providing care produces greater selection for cognition than an avoidance strategy, and 3) whether care-giving alters the progression of the disease through the population. The greatest selection was produced by diseases with lower risks to the care-giver and prevalences low enough not to disrupt the kin networks. When care-giving and avoidance strategies were compared, only care-giving reduced the severity of the disease outbreaks and subsequent population crashes. The greatest selection for increased cognitive abilities occurred early in the model runs when the outbreaks and population crashes were most severe. Therefore, over the course of human evolution, repeated introductions of novel diseases into naïve populations could have produced sustained selection for increased disease recognition and care-giving behavior, leading to the evolution of increased cognition, social complexity, and, eventually, medical care in humans. Finally, we lay out predictions derived from our disease recognition hypothesis that we encourage paleoanthropologists, bioarchaeologists, primatologists, and paleogeneticists to test.
为患病的同种个体提供照料这一行为的出现，必定是人类社会性进化过程中的一个转折点。在种群层面，在社会复杂性不断增加的时期，照料行为或许将社会传播疾病的代价降至了最低，尽管个体照料者可能会面临更高的传播风险。我们认为，照料行为很可能起源于亲属网络之中，在那里，照料患病亲属所带来的适应性增强或许能够平衡其中的代价。我们检验了一个关于人类认知进化的新假说，即疾病可能促使了识别同种个体何时被感染的认知能力的产生。由于疾病可能会产生一些症状，而这些症状很可能能够通过社会认知所不可或缺的感知 - 认知途径被察觉，所以我们认为疾病识别和社会认知可能是共同进化的。我们运用基于主体的建模方法来检验：1）在何种条件下疾病能够促使亲属之间疾病识别能力的增强以及照料行为的出现；2）与回避策略相比，提供照料是否会对认知产生更强的选择作用；3）照料行为是否会改变疾病在种群中的传播进程。对照料者风险较低且流行程度低到不至于破坏亲属网络的疾病，产生了最大的选择作用。当对比照料行为和回避策略时，只有照料行为降低了疾病爆发的严重程度以及随后的种群崩溃。在模型运行初期，当疾病爆发和种群崩溃最为严重时，对认知能力增强的选择作用最大。因此，在人类进化过程中，新疾病反复传入缺乏免疫力的人群中，可能持续产生了对疾病识别能力增强和照料行为的选择作用，从而导致了人类认知能力的提升、社会复杂性的增加，最终促成了医疗护理的出现。最后，我们列出了从疾病识别假说中推导出来的预测，鼓励古人类学家、生物考古学家、灵长类动物学家和古遗传学家去进行检验。
