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What do animal signals do? Joseph Soltis * Education and Science, Disney’s Animal Kingdom article info Article history: Received 25 August 2009 Initial acceptance 10 September 2009 Final acceptance 10 September 2009 Available online 23 October 2009 MS. number: AS-09-00560 Keywords: alarm call communication functionalist approach functionally referential signalling language signalling vocalization Scientific descriptions of animal behaviour entail all manner of controversies, in particular when such descriptions touch upon animal minds. In a recent essay in Animal Behaviour , Rendall et al. (2009) argued that the scientific description of animal signalling relies too heavily on human language metaphors and related concepts of information transfer. These authors go on to argue that such concepts lead to, among other things, the unwitting and unwarranted attribution of consciousness, intentionality and the capacity for mental representation to animals. The so-called ‘functional’ approach to describing animal behaviour is designed to avoid such unwarranted attributions, as it is not committed to any particular view on animal minds (Macedonia & Evans 1993; Hauser 1996, pp. 508–509). The authors bring up this point very briefly, and just as quickly dismiss this approach. In this response, I use the subject of predator alarm calls to show why the functional approach should not be so casually dismissed as a useful device for describing animal behaviour. A ‘functionally referential’ predator alarm call would be one (1) that is produced regularly in the presence of a predator and (2) that elicits behaviour from a listener that would occur in the presence of that predator, even when the predator is not present. Such ‘functionally referential’ signalling could arise from a broad range of mecha- nisms that support the regular production of the sound by callers and the regular behavioural responses of listeners. I provide two such scenarios. Scenario A When exposed to predators, animals show a fear response, which includes a specific type of vocalization. Other animals of the same species have, through a simple learning mechanism, associ- ated this sound with the presence of predators and engage in predator avoidance behaviours when exposed to the sound. Senders are not conscious, and do not deliberately call to provide information to other animals. The acoustic output is due solely to physiological processes associated with increased affect intensity due to the presence of a predator. Likewise, the receivers are not conscious, and are not aware of the source of the sound. Their behavioural response to the vocalization is due solely to an evolved or learned stimulus response mechanism. While the system behaves functionally as an alarm call (i.e. it is ‘functionally refer- ential’), there is little or no similarity to human language, as the causal mechanisms supporting the production of and behavioural response to the vocalization are not the same as those supporting such an alarm call in human language, for example, in the form of a word (e.g. ‘Warning!’) or a sentence (e.g. ‘There is a predator!’). * Correspondence: J. Soltis, Education and Science, Disney’s Animal Kingdom, 1200 North Savannah Circle East, Bay Lake, FL 32830, U.S.A. E-mail address: [email protected] Contents lists available at ScienceDirect Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav 0003-3472/$38.00 Ó 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.anbehav.2009.09.030 Animal Behaviour 78 (2009) 1485–1486

What do animal signals do?

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Page 1: What do animal signals do?

lable at ScienceDirect

Animal Behaviour 78 (2009) 1485–1486

Contents lists avai

Animal Behaviour

journal homepage: www.elsevier .com/locate/anbehav

What do animal signals do?

Joseph Soltis*

Education and Science, Disney’s Animal Kingdom

a r t i c l e i n f o

Article history:Received 25 August 2009Initial acceptance 10 September 2009Final acceptance 10 September 2009Available online 23 October 2009MS. number: AS-09-00560

Keywords:alarm callcommunicationfunctionalist approachfunctionally referential signallinglanguagesignallingvocalization

* Correspondence: J. Soltis, Education and Science1200 North Savannah Circle East, Bay Lake, FL 32830

E-mail address: [email protected]

0003-3472/$38.00 � 2009 The Association for the Studoi:10.1016/j.anbehav.2009.09.030

Scientific descriptions of animal behaviour entail all manner ofcontroversies, in particular when such descriptions touch uponanimal minds. In a recent essay in Animal Behaviour, Rendall et al.(2009) argued that the scientific description of animal signallingrelies too heavily on human language metaphors and relatedconcepts of information transfer. These authors go on to argue thatsuch concepts lead to, among other things, the unwitting andunwarranted attribution of consciousness, intentionality and thecapacity for mental representation to animals. The so-called‘functional’ approach to describing animal behaviour is designed toavoid such unwarranted attributions, as it is not committed to anyparticular view on animal minds (Macedonia & Evans 1993; Hauser1996, pp. 508–509). The authors bring up this point very briefly,and just as quickly dismiss this approach.

In this response, I use the subject of predator alarm calls to showwhy the functional approach should not be so casually dismissed asa useful device for describing animal behaviour. A ‘functionallyreferential’ predator alarm call would be one (1) that is producedregularly in the presence of a predator and (2) that elicits behaviourfrom a listener that would occur in the presence of that predator,even when the predator is not present. Such ‘functionally

, Disney’s Animal Kingdom,, U.S.A.

dy of Animal Behaviour. Publishe

referential’ signalling could arise from a broad range of mecha-nisms that support the regular production of the sound by callersand the regular behavioural responses of listeners. I provide twosuch scenarios.

Scenario A

When exposed to predators, animals show a fear response,which includes a specific type of vocalization. Other animals of thesame species have, through a simple learning mechanism, associ-ated this sound with the presence of predators and engage inpredator avoidance behaviours when exposed to the sound.Senders are not conscious, and do not deliberately call to provideinformation to other animals. The acoustic output is due solely tophysiological processes associated with increased affect intensitydue to the presence of a predator. Likewise, the receivers are notconscious, and are not aware of the source of the sound. Theirbehavioural response to the vocalization is due solely to an evolvedor learned stimulus response mechanism. While the systembehaves functionally as an alarm call (i.e. it is ‘functionally refer-ential’), there is little or no similarity to human language, as thecausal mechanisms supporting the production of and behaviouralresponse to the vocalization are not the same as those supportingsuch an alarm call in human language, for example, in the form ofa word (e.g. ‘Warning!’) or a sentence (e.g. ‘There is a predator!’).

d by Elsevier Ltd. All rights reserved.

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J. Soltis / Animal Behaviour 78 (2009) 1485–14861486

Scenario B

When exposed to predators, animals show a fear response, butalso intentionally produce a specific type of vocalization to warnother animals about the presence of predators so that the listenerscan escape. When other animals hear this specific call, they knowthat it refers to the presence of predators in the environment, andengage in appropriate predator avoidance behaviours. Senders holdconscious representations of a predator, and deliberately call towarn other animals. The acoustic output is due to a conscious effortto communicate to other animals using a vocalization mutuallyunderstood to represent a predator. Likewise, the receivers holdconscious representations of a predator, and are aware thata conspecific has produced a mutually understood vocalization asa warning about an observed predator. Their behavioural responseis a deliberate act taken in response to the understood meaning ofthe perceived vocalization. This system not only behaves func-tionally as an alarm call (i.e. it is functionally referential), but issimilar to, if not the same as, human language, as the causalmechanisms supporting the production of and behaviouralresponse to the vocalization are similar to, or the same as, thosesupporting such an alarm call in human language, for example, inthe form of a word (e.g. ‘Warning!’) or a sentence (e.g. ‘There isa predator!’).

Since in many cases we do not know enough about the mech-anisms and internal states of animals to always distinguishbetween scenarios such as A and B (and many, many otherscenarios), I agree with the authors that making strong claimsabout the presence or absence of animal consciousness, intentionsand mental representation is foolhardy. The functionalist approachto animal behaviour description avoids such unnecessary andunwarranted claims. The authors clearly disagree, arguing that thephrase ‘functionally referential’ is an oxymoron, because the phraseacknowledges that animal signals ‘may never meet the semanticsine qua non of human language’ (Rendall et al. 2009, page 236).This is true, but the phrase is not therefore oxymoronic. Rather, it istherefore agnostic. Those who categorically deny language-likecapabilities to animals, and those who promiscuously ascribe such

capabilities to animals, are twin believers. Adopting a functionalistapproach avoids these pitfalls by not attempting to providepremature explications of these extremely contentious scientificand philosophical conundrums related to animal consciousness.

In the absence of knowledge about mechanisms and the internalstates of animals, the following is an example of the type ofdescription that Rendall et al. (2009) would eschew: ‘In the pres-ence of predators, these animals produce alarm calls that providereferential information about those predators to conspecifics, whouse that information to guide their behaviour in such a way as toavoid predation’. In the absence of evidence, such an explanationgoes too far in implying human language capabilities. A moreneutral, ‘functional’ explanation might be worded as follows: ‘Theanimals produce vocalizations in the presence of predators thatfunction as alarm calls, as those vocalizations elicit predatoravoidance behaviour in conspecifics’. Such a functional explanation,properly understood, avoids mental attributions to animals, andconstitutes a convenient shorthand, avoiding, when unwarrantedby evidence, limitless and lengthy alternative explanations, such asthe hypothetical scenarios A and B provided above.

I took a brief look at some of my own work on animal signalling,and have sometimes described the behaviour of animals in waysthat may have inadvertently implied language-like capacities. Wewould all do well to take the essay by Rendall, Owren and Ryan veryseriously, keeping it in mind when we describe behaviour, so thatwe avoid implying human-like attributes to animals when it isunwarranted. Scrupulously adopting a functionalist approach,when evidence about the internal states of animals is unknown (orunknowable), can help achieve this goal.

References

Hauser, M. D. 1996. The Evolution of Communication. Cambridge, Massachusetts:MIT Press.

Macedonia, J. M. & Evans, C. S. 1993. Variation among mammalian alarm callsystems and the problem of meaning in animal signals. Ethology, 93, 177–197.

Rendall, D., Owren, M. J. & Ryan, M. J. 2009. What do animal signals mean? AnimalBehaviour, 78, 233–240.