Referential alarm calling behaviour in New World primates

There is relatively good evidence that non-human primates can communicate about objects and events in their envi- ronment in ways that allow recipients to draw inferences about the nature of the event experienced by the signaller. In some spe- cies, there is also evidence that the basic semantic units are not individual calls, but call sequences and the combinations gener- ated by them. These two findings are relevant to theories pertaining to the origins of human language because of the resemblances of these phenomena with linguistic reference and syntactic organisation. Until recently, however, most research efforts on the primate origins of human language have involved Old World species with comparatively few systematic studies on New World monkeys, which has prevented insights into the deeper phylogenetic roots and evolutionary origins of language-relevant capaci- ties. To address this, we review the older primate literature and very recent evidence for functionally referential communication and call combinations in New World primates. Within the existing literature there is ample evidence in both Callitrichids and Ce- bids for acoustically distinct call variants given to external disturbances that are accompanied by distinct behavioural responses. A general pattern is that one call type is typically produced in response to a wide range of general disturbances, often on the ground but also including inter-group encounters, while another call type is produced in response to a much narrower range of aerial threats. This pattern is already described for Old World monkeys and Prosimians, suggesting an early evolutionary origin. Second, recent work with black-fronted tiff monkeys has produced evidence for different alarm call sequences consisting of acoustically distinct call types. These sequences appear to encode several aspects of the predation event simultaneously, notably predator type and location. Since meaningful call sequences have already been described in Old World primates, we suggest that basic combi- natorial vocal communication has evolved in the primate lineage long before the advent of language. Moreover, it is possible that some of these communicative abilities have evolved even earlier, or independently, as there is comparable evidence in other taxonomic groups. We discuss these findings in an attempt to shed further light on the primate stock from which human language has arisen [Current Zoology 58 （5）： 680-697, 2012].

Specific responses of cuckoo hosts to different alarm signals according to breeding stage:a test of the offspring value hypothesis

The selective pressure exerted by avian brood parasites forces their hosts to evolve specific defense strategies.When subject to brood parasite attack,avian hosts will often emit alarm calls.To date,few studies have examined whether and how host responses to different alarm calls indicative of different enemies vary with the hosts breeding stage.We carried out alarm call playback experiments during both the egg and nestling stages of the oriental reed warbler Acrocephalus orientals,a host of the common cuckoo Cuculus canorus.The playback exemplars were selected from recorded alarm calls of the warbler to the presenee of common cuckoos,sparrowhawks Accipiter nisus,and oriental turtle doves Streptopelia orientalis,which represented brood parasite,predator,and harmless control,respectively.The results showed that the oriental reed warblers did not discriminate alarm calls issued to different intruder types,but the intensity of the response was significantly higher in the nestling stage than in the egg stage.Attack behavior related to sparrowhawk alarm calls was absent in the egg stage,but aggressive behavior in creased dramatically and exceeded the attack frequency in response to the cuckoo alarm call in the nestling stage,implying a shift in the tradeoff between the parents'own survival and the loss of offspring.Alarm calls attracted a larger nu mber of con specifics tha n members of other species.In gen eral,the oriental reed warbler had consistently stronger responses to different alarm calls in the nestling stage than in the egg stage,supporting the offspring value hypothesis.