Campbell's monkeys concatenate vocalizations into context-specific call sequences - PubMed (original) (raw)

Campbell's monkeys concatenate vocalizations into context-specific call sequences

Karim Ouattara et al. Proc Natl Acad Sci U S A. 2009.

Abstract

Primate vocal behavior is often considered irrelevant in modeling human language evolution, mainly because of the caller's limited vocal control and apparent lack of intentional signaling. Here, we present the results of a long-term study on Campbell's monkeys, which has revealed an unrivaled degree of vocal complexity. Adult males produced six different loud call types, which they combined into various sequences in highly context-specific ways. We found stereotyped sequences that were strongly associated with cohesion and travel, falling trees, neighboring groups, nonpredatory animals, unspecific predatory threat, and specific predator classes. Within the responses to predators, we found that crowned eagles triggered four and leopards three different sequences, depending on how the caller learned about their presence. Callers followed a number of principles when concatenating sequences, such as nonrandom transition probabilities of call types, addition of specific calls into an existing sequence to form a different one, or recombination of two sequences to form a third one. We conclude that these primates have overcome some of the constraints of limited vocal control by combinatorial organization. As the different sequences were so tightly linked to specific external events, the Campbell's monkey call system may be the most complex example of 'proto-syntax' in animal communication known to date.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.

Fig. 1.

Spectrograms of the six call types produced by males. Three calls could be described in terms of an acoustically invariable affix following the call stem. +, indicates that call stem is trailed by a suffix, an acoustically invariable “oo” utterance.

Fig. 2.

Fig. 2.

Composition of call sequences in different behavioral contexts. “Alarm” indicates leopard or eagle alarm calls given by sympatric Diana monkeys.

Fig. 3.

Fig. 3.

Geographical distribution of call sequences given during intergroup encounters (A) and after falling of trees or large branches (B). The two study groups were habituated to human observers and had adjacent territories. Each square represents a 100 × 100 m area. We divided each home range into two parts: center (dark squares) and periphery (light squares). The two groups were surrounded by four other semihabituated groups. Stars indicate the location of calling sequences (A, n = 71; B, n = 53).

Fig. 4.

Fig. 4.

Relative distribution of different call types within predator sequences with varying levels of predator threat. (A) eagle, (B) leopard. Fisher exact test (***, P < 0.001) were used to compare the relative contribution of obligatory (black) vs. optional (white) call types in low threat situations (1, mainly Diana monkey alarms; 2, playback of predator vocalizations) or high threat circumstances (3, visual predator models; 4, real predator encounters).

Similar articles

Cited by

References

    1. Snowdon CT, Hausberger M. Socials Influences on Vocal Development. Cambridge, UK: Univ Press; 1997.
    1. Elowson AM, Snowdon CT, Lazaro-Perea C. “Babbling” and social context in infant monkeys: Parallels to human infants. Trends Cogn Sci. 1998;2:31–37. - PubMed
    1. Hausberger M, Richard-Yiris M-A, Henry L, Lepage L, Schmidt I. Song sharing reflects the social organization in captive group of European starling (Sturnus vulgaris) J Comp Psychol. 1995;109:222–241.
    1. Tyack PL. Dolphins whistle: A signature tune. Science. 2000;289:1310–1311. - PubMed
    1. Lemasson A, Hausberger M. Patterns of vocal sharing social dynamics in captive group of Campbell's monkeys (Cercopithecus campbelli campbelli) J Comp Psychol. 2004;118:347–359. - PubMed

Publication types

MeSH terms

LinkOut - more resources