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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 \u2018proto-syntax\u2019 in animal communication known to date.<\/jats:p>","DOI":"10.1073\/pnas.0908118106","type":"journal-article","created":{"date-parts":[[2009,12,9]],"date-time":"2009-12-09T21:40:00Z","timestamp":1260394800000},"page":"22026-22031","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":268,"title":["Campbell's monkeys concatenate vocalizations into context-specific call sequences"],"prefix":"10.1073","volume":"106","author":[{"given":"Karim","family":"Ouattara","sequence":"first","affiliation":[{"name":"Laboratoire EthoS \u201cEthologie Animale et Humaine,\u201d Unit\u00e9 Mixte de Recherche 6552, Centre National de la Recherche Scientifique, Universit\u00e9 de Rennes 1, Station Biologique, 35380 Paimpont, France;"},{"name":"Centre Suisse de Recherches Scientifiques, Ta\u00ef Monkey Project, 01 BP1303, Abidjan 01, C\u00f4te d'Ivoire;"},{"name":"Laboratoire de Zoologie et de Biologie Animale, Universit\u00e9 de Cocody, 10 BP770, Abidjan 10, C\u00f4te d'Ivoire; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alban","family":"Lemasson","sequence":"additional","affiliation":[{"name":"Laboratoire EthoS \u201cEthologie Animale et Humaine,\u201d Unit\u00e9 Mixte de Recherche 6552, Centre National de la Recherche Scientifique, Universit\u00e9 de Rennes 1, Station Biologique, 35380 Paimpont, France;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Klaus","family":"Zuberb\u00fchler","sequence":"additional","affiliation":[{"name":"School of Psychology, University of St. Andrews, KY16 9JP Saint Andrews, Scotland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2009,12,22]]},"reference":[{"key":"e_1_3_3_1_2","doi-asserted-by":"publisher","DOI":"10.1017\/CBO9780511758843"},{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1364-6613(97)01115-7"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1037\/0735-7036.109.3.222"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.289.5483.1310"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.1037\/0735-7036.118.3.347"},{"key":"e_1_3_3_6_2","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1017\/CBO9780511758843.008","volume-title":"Social Influences on Vocal Development","author":"Hausberger M","year":"1997","unstructured":"M Hausberger Social Influences on Vocal Development, eds CT Snowdon, M Hausberger (Univ Press, Cambridge, UK), pp. 128\u2013156 (1997)."},{"key":"e_1_3_3_7_2","doi-asserted-by":"publisher","DOI":"10.1006\/anbe.2002.3012"},{"key":"e_1_3_3_8_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1439-0310.2006.01103.x"},{"key":"e_1_3_3_9_2","doi-asserted-by":"publisher","DOI":"10.1006\/anbe.1993.1096"},{"key":"e_1_3_3_10_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0002431"},{"key":"e_1_3_3_11_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0003-3472(80)80097-2"},{"key":"e_1_3_3_12_2","doi-asserted-by":"publisher","DOI":"10.1098\/rspb.2003.2619"},{"key":"e_1_3_3_13_2","doi-asserted-by":"publisher","DOI":"10.1037\/0735-7036.113.1.33"},{"key":"e_1_3_3_14_2","doi-asserted-by":"publisher","DOI":"10.1037\/0735-7036.119.1.67"},{"key":"e_1_3_3_15_2","doi-asserted-by":"publisher","DOI":"10.1007\/s10071-009-0220-5"},{"key":"e_1_3_3_16_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0006295"},{"key":"e_1_3_3_17_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.91.9.3946"},{"key":"e_1_3_3_18_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0002203"},{"key":"e_1_3_3_19_2","first-page":"1727","article-title":"Right ear advantage for conspecific calls in adults and subadults, but not infants, California sea lions (Zalophuscalifornianus): Hemispheric specialization for communication?","volume":"21","author":"B\u00f6ye M","year":"2005","unstructured":"M B\u00f6ye, O G\u00fcnt\u00fcrk\u00fcn, J Vauclair, Right ear advantage for conspecific calls in adults and subadults, but not infants, California sea lions (Zalophuscalifornianus): Hemispheric specialization for communication? 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