Scott-Phillips Thomas C, Gurney James, Ivens Alasdair, Diggle Stephen P, Popat Roman
Department of Anthropology, Durham University, Durham, United Kingdom.
School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.
PLoS One. 2014 Apr 23;9(4):e95929. doi: 10.1371/journal.pone.0095929. eCollection 2014.
Combinatorial communication, in which two signals are used together to achieve an effect that is different to the sum of the effects of the component parts, is apparently rare in nature: it is ubiquitous in human language, appears to exist in a simple form in some non-human primates, but has not been demonstrated in other species. This observed distribution has led to the pair of related suggestions, that (i) these differences in the complexity of observed communication systems reflect cognitive differences between species; and (ii) that the combinations we see in non-human primates may be evolutionary pre-cursors of human language. Here we replicate the landmark experiments on combinatorial communication in non-human primates, but in an entirely different species, unrelated to humans, and with no higher cognition: the bacterium Pseudomonas aeruginosa. Using the same general methods as the primate studies, we find the same general pattern of results: the effect of the combined signal differs from the composite effect of the two individual signals. This suggests that advanced cognitive abilities and large brains do not necessarily explain why some species have combinatorial communication systems and others do not. We thus argue that it is premature to conclude that the systems observed in non-human primates are evolutionarily related to language. Our results illustrate the value of an extremely broad approach to comparative research.
组合通信是指将两种信号一起使用，以实现一种不同于各组成部分效果之和的效应。组合通信在自然界中显然很少见：它在人类语言中无处不在，在一些非人类灵长类动物中似乎以一种简单的形式存在，但在其他物种中尚未得到证实。这种观察到的分布情况引发了一对相关的观点：（i）观察到的通信系统复杂性的这些差异反映了物种之间的认知差异；（ii）我们在非人类灵长类动物中看到的组合可能是人类语言的进化先驱。在这里，我们重复了关于非人类灵长类动物组合通信的具有里程碑意义的实验，但实验对象是一个与人类完全不同、没有高级认知能力的物种：铜绿假单胞菌。使用与灵长类动物研究相同的一般方法，我们得到了相同的一般结果模式：组合信号的效果不同于两个单独信号的综合效果。这表明，高级认知能力和大脑体积大并不一定能解释为什么有些物种有组合通信系统而有些物种没有。因此，我们认为现在就得出在非人类灵长类动物中观察到的系统与语言在进化上相关的结论还为时过早。我们的研究结果说明了采用极其广泛的方法进行比较研究的价值。
