Gavrilets Sergey, Vose Aaron
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA.
Proc Natl Acad Sci U S A. 2006 Nov 7;103(45):16823-8. doi: 10.1073/pnas.0601428103. Epub 2006 Oct 30.
The "Machiavellian intelligence" hypothesis (or the "social brain" hypothesis) posits that large brains and distinctive cognitive abilities of humans have evolved via intense social competition in which social competitors developed increasingly sophisticated "Machiavellian" strategies as a means to achieve higher social and reproductive success. Here we build a mathematical model aiming to explore this hypothesis. In the model, genes control brains which invent and learn strategies (memes) which are used by males to gain advantage in competition for mates. We show that the dynamics of intelligence has three distinct phases. During the dormant phase only newly invented memes are present in the population. During the cognitive explosion phase the population's meme count and the learning ability, cerebral capacity (controlling the number of different memes that the brain can learn and use), and Machiavellian fitness of individuals increase in a runaway fashion. During the saturation phase natural selection resulting from the costs of having large brains checks further increases in cognitive abilities. Overall, our results suggest that the mechanisms underlying the "Machiavellian intelligence" hypothesis can indeed result in the evolution of significant cognitive abilities on the time scale of 10 to 20 thousand generations. We show that cerebral capacity evolves faster and to a larger degree than learning ability. Our model suggests that there may be a tendency toward a reduction in cognitive abilities (driven by the costs of having a large brain) as the reproductive advantage of having a large brain decreases and the exposure to memes increases in modern societies.
“马基雅维利式智能”假说（或“社会大脑”假说）认为，人类的大脑和独特认知能力是通过激烈的社会竞争进化而来的，在这种竞争中，社会竞争者发展出越来越复杂的“马基雅维利式”策略，以实现更高的社会和生殖成功率。在此，我们构建了一个数学模型，旨在探究这一假说。在该模型中，基因控制大脑，大脑发明并学习策略（模因），雄性利用这些策略在争夺配偶的竞争中获取优势。我们发现，智能的动态变化有三个不同阶段。在休眠阶段，种群中仅存在新发明的模因。在认知爆炸阶段，种群的模因数量、学习能力、大脑容量（控制大脑能够学习和使用的不同模因数量）以及个体的马基雅维利适应性会以失控的方式增加。在饱和阶段，因大脑庞大带来的成本所导致的自然选择会抑制认知能力的进一步提升。总体而言，我们的结果表明，“马基雅维利式智能”假说背后的机制确实能够在1万到2万代的时间尺度上导致显著认知能力的进化。我们发现，大脑容量的进化速度更快，程度也比学习能力更大。我们的模型表明，在现代社会中，随着大脑庞大所带来的生殖优势降低以及接触模因的机会增加，可能存在认知能力下降的趋势（由大脑庞大的成本驱动）。
