Kolodny Oren, Creanza Nicole, Feldman Marcus W
Department of Biology, Stanford University, Stanford, California, United States of America.
Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America.
PLoS Comput Biol. 2016 Dec 30;12(12):e1005302. doi: 10.1371/journal.pcbi.1005302. eCollection 2016 Dec.
One of the most puzzling features of the prehistoric record of hominid stone tools is its apparent punctuation: it consists of abrupt bursts of dramatic change that separate long periods of largely unchanging technology. Within each such period, small punctuated cultural modifications take place. Punctuation on multiple timescales and magnitudes is also found in cultural trajectories from historical times. To explain these sharp cultural bursts, researchers invoke such external factors as sudden environmental change, rapid cognitive or morphological change in the hominids that created the tools, or replacement of one species or population by another. Here we propose a dynamic model of cultural evolution that accommodates empirical observations: without invoking external factors, it gives rise to a pattern of rare, dramatic cultural bursts, interspersed by more frequent, smaller, punctuated cultural modifications. Our model includes interdependent innovation processes that occur at different rates. It also incorporates a realistic aspect of cultural evolution: cultural innovations, such as those that increase food availability or that affect cultural transmission, can change the parameters that affect cultural evolution, thereby altering the population's cultural dynamics and steady state. This steady state can be regarded as a cultural carrying capacity. These parameter-changing cultural innovations occur very rarely, but whenever one occurs, it triggers a dramatic shift towards a new cultural steady state. The smaller and more frequent punctuated cultural changes, on the other hand, are brought about by innovations that spur the invention of further, related, technology, and which occur regardless of whether the population is near its cultural steady state. Our model suggests that common interpretations of cultural shifts as evidence of biological change, for example the appearance of behaviorally modern humans, may be unwarranted.
它由急剧的戏剧性变化爆发组成，这些变化将技术基本不变的漫长时期分隔开来。在每个这样的时期内，会发生小规模的间断性文化变革。在历史时期的文化轨迹中也发现了多个时间尺度和量级上的间断性。为了解释这些剧烈的文化爆发，研究人员援引了诸如突然的环境变化、制造工具的人类在认知或形态上的快速变化，或者一个物种或群体被另一个物种或群体取代等外部因素。在这里，我们提出了一个文化进化的动态模型，该模型符合实证观察结果：在不援引外部因素的情况下，它会产生一种模式，即罕见的、剧烈的文化爆发，其间穿插着更频繁、规模更小的间断性文化变革。我们的模型包括以不同速率发生的相互依存的创新过程。它还纳入了文化进化的一个现实方面：文化创新，比如那些增加食物供应或影响文化传播的创新，可以改变影响文化进化的参数，从而改变群体的文化动态和稳态。这种稳态可以被视为一种文化承载能力。这些改变参数的文化创新非常罕见，但每当有一个发生时，它就会引发向新的文化稳态的急剧转变。另一方面，规模更小、更频繁的间断性文化变化是由刺激进一步相关技术发明的创新带来的，无论群体是否接近其文化稳态，这些创新都会发生。我们的模型表明，将文化转变普遍解释为生物变化的证据，例如行为现代人类的出现，可能是没有根据的。
