社交结构在动物交流中究竟扮演着什么样的角色？这一直是科学家们津津乐道的话题。除了人类以外，每种灵长类动物都有其独特的一系列叫声。但这背后似乎还有着一定的灵活性，比如，你可以从长臂猿的“口音”判断出它来自哪里。发表在《BMC Evolutionary Biology》杂志上的一项新研究，对坎贝尔的猴子在先天和后天方面的一些问题进行了研究，结果显示，非人类的灵长类动物跟人类一样是通过学习模仿来掌握“语言”的。
该研究的研究对象是来自非洲Taï National Park的野生坎贝尔猴(Cercopithecus campbelli campbelli)。首先，科学家观察并记录了雌性猴子在行走、觅食和休憩时的社交活动（一起玩耍的时间）和“聊天记录”。然后，科学家们用DNA分析仪对这些猴子的排泄物进行检测比对从而确认出它们的基因相似度（即血缘关系）。这些猴子在Taï Monkey Project Research Station附近住了有十多年了，所以科学家们对这个家族的组成了如指掌。这个大家族包括一个雄性，4个或者6个雌性，还有它们的后代。
领导该项研究的Alban Lemasson博士解释道：“虽然每个雌性都有其独特的发音，但是它们还是会互相学习彼此的习性。这些雌性在‘口音’方面的相似度取决于它们在一起玩耍的时间长短（以及它们的玩伴是谁），而不是取决于基因相似度。这就意味着，灵长类动物的总体发声机制是由基因决定的，而该机制具体的表现形式则是受它们的社交圈影响的。这种行为同样符合‘人类的语言能力是从原始灵长类动物的发声法和社交模式中逐渐发展出来的’的理论。”
Social learning of vocal structure in a nonhuman primate?
Alban Lemasson, Karim Ouattara, Eric J Petit and Klaus Zuberbuhler
Background: Non-human primate communication is thought to be fundamentally different from human speech, mainly due to vast differences in vocal control. The lack of these abilities in non-human primates is especially striking if compared to some marine mammals and bird species, which has generated somewhat of an evolutionary conundrum. What are the biological roots and underlying evolutionary pressures of the human ability to voluntarily control sound production and learn the vocal utterances of others? One hypothesis is that this capacity has evolved gradually in humans from an ancestral stage that resembled the vocal behavior of modern primates. Support for this has come from studies that have documented limited vocal flexibility and convergence in different primate species, typically in calls used during social interactions. The mechanisms underlying these patterns, however, are currently unknown. Specifically, it has been difficult to rule out explanations based on genetic relatedness, suggesting that such vocal flexibility may not be the result of social learning.
Results: To address this point, we compared the degree of acoustic similarity of contact calls in free-ranging Campbell's monkeys as a function of their social bonds and genetic relatedness. We calculated three different indices to compare the similarities between the calls' frequency contours, the duration of grooming interactions and the microsatellite-based genetic relatedness between partners. We found a significantly positive relation between bond strength and acoustic similarity that was independent of genetic relatedness.
Conclusion: Genetic factors determine the general species-specific call repertoire of a primate species, while social factors can influence the fine structure of some the call types. The finding is in line with the more general hypothesis that human speech has evolved gradually from earlier primate-like vocal communication.
文献链接：https://www.biomedcentral.com/content/pdf/1471-2148-11-362.pdf
