Forms and meaning of primate communication

Presenter: Roya ShariatiANU College of Archaeology and

AnthropologySupervisor: Prof. Colin Groves

What is Communication?

Communication is the transfer of information from one Primate

to another. The message or signal is passed between a sender

and a receiver. The ability to detect and respond to stimuli is

essential for survival. By detecting changes in the external

environment, humans and other animals are able to respond

appropriately.

Form Of Communication

GesturesFacial ExpressionGaze FollowingVocalizationOlfactory communicationElectro Communication

Pictures from science daily web and wikipidia

Pictures from Sciencedaily website and Wikipedia

Vocalization:

Many of primates communicate through vocalizations.

Primate communication also involves mental representation in some

cases, most clearly in the representational vocalizations used by

primate species.

Vocalization are believed to serve a variety of functions, including

territorial advertisement; intergroup intimidation and spacing;

announcing the precise locality of specific individuals, food sources, or

danger; and strengthening intragroup cohesion.

Vocal organs (Chiba & Kiiama 1940)• Non-human primates have vocal organs similar to ours, but

– the size of their tongue relative to the size of the mouth is much larger

– their pharynx (area between the larynx and the mouth) is shorter

Primate vocalizations

• Both non-human primates and humans use the larynx for the source of sound production and the oral cavity above the larynx as the filter.

Kratzenstein‘s geometric-acoustic considerations based on reflections within elliptical cones (Gessinger 1994)

• Non-human primates have much larger tongue: not advantageous in manipulating the shape of the vocal tract.

• Non-human primates have shorter pharynx: less room to play with the shape of the vocal tract.

– But they have lower risk of choking on food

Source-filter theoryThe source-filter theory describes speech production as a two stage process involving the generation of a sound source, with its own spectral shape and spectral fine structure, which is then shaped or filtered by the resonant properties of the vocal tract.

The vowel, its nature and structure / by Tsutomu Chiba and Masato Kajiyama 1941

Source-filter theory: illustration

Source filter theory and vocalization

• So what a vocalization sounds like depends on whatthe sound source is like and how that source is filtered

• The source can be created by vibrating the vocal foldsin the larynx

– How fast the vocal folds vibrate will determine the fundamental frequency of the sound

• The shape of the vocal tract above the larynx determines the nature of the filter – which frequencies are amplified and which are attenuated

– One can make sounds of equal pitch but different quality (timbre)

Barks and pant-threats• Lips are slightly protruded and maximally spread

apart at the beginning of each sound– The lower jaw, or the mandible drops to the lowest point– This is more prominent for barks than for

pant-threats– The teeth are partially separated during the production

• Barks are more likely to be associated with physical aggression

Noisy and undulating screams

• Produced by individuals being threatened by a dominant member of the group

– Noisy screams are more consistently associated with physical attack than undulating screams

• The lips are retracted, revealing the teeth– Lip retraction appears more prominent for

noisy scream than for undulating scream

Coos and grunts• Coos and grunts are produced during group

movement, affiliative activities, and when one approaches another to groom

• When producing coos, the lips are separated fairly wide and somewhat protruded while the mandible is lowered

• When producing grunts, lips are separated, often to a negligible degree, and there is no lip protrusion

links• Rhesus monkey callshttp://www.wjh.harvard.edu/~mnkylab/media/rhesuscalls.htmlhttp://www.soundboard.com/sb/Rhesus_Monkey_sounds.aspx

• Rhesus monkey articulation– Hauser et al. (1993). The role of articulation in the production ofrhesus monkey, Macaca mulatta, vocalizations. Anim. Behav., 45,423-433.http://galliform.psy.mq.edu.au/Reprints/Hauser_Evans&Marler_1993.pdf

• – Lieberman et al. (1980). Vocal tract limitations on the vowel repertoires of rhesus monkey and other nonhuman primates, Science, 164, 1185-1187.

http://web.haskins.yale.edu/Reprints/HL0080.pdf

Call Context

• Food Many primates produce distinct calls when discovering or eating food.

• Predators Many primates produce alarm calls in response to predator (Cheney and

Seyfarth, 1990),

• Mating In most of species both sexes produce copulation calls (Hauser, 1996)

Caller Identity

• Individual• Sex• Group membership

Rhesus food discovery vocalizations

• When rhesus macaques discover food, they call out, at which point other group members come running

• Hauser (1996) catalogued five different food calls– ‘warbles’, ‘chirps’, and ‘harmonic arches’ are

associated with rare and high-quality foods (e.g. coconut)– ‘coos’ and ‘grunts’ are for common, low-quality

foods

• ‘Silent discoverers’ who are caught with food are severely beaten up, and this is true for high and low ranking individuals

• Males make food calls less often than females

Food calls are intentional, not reflexive

• When individuals discover food, they first scan the area, looking for enemies and/or allies

• Members of social groups have different calling behaviours than males who live peripherally, waiting to join a social group

– When peripheral males find food, they never call

– These peripheral silent discoverers never receive targeted aggression

• These observations suggest that rhesus macaques can intentionally withhold information about food discoveries

Rhesus mating vocalizations

• Males produce extremely loud and individually distinctive screams during mating

• Hauser (1996) found that males who call during copulation obtain significantly more mating than males who were silent

• However, vocal males also received significantly more aggression than did silent males

• This suggests there are potential survival costs to calling (natural selection pressure), but potential reproductive benefits (sexual selection pressure)

Gibbon songs

• Gibbons, unique among non-human primates, produce complex songs in order to attract mates, advertise pair bonds (duets), repel introducers, and warn each other of predators

• http://www.gibbons.de/main/sound/sounds/07hool_sounds/hoDuett88a2027.wav

Gibbons (Hylobates spp.) produce loud

and long song bouts that are mostly

exhibited by mated pairs. Typically,

mates combine their partly sex-specific

repetoire in relatively rigid, precisely

timed, and complex vocal interactions to

produce well-patterned duets. A cross-

species comparison reveals that singing

behaviour evolved several times

independently in the order of primates.

Most likely, loud calls were the substrate

from which singing evolved in each line.

(Geissmann, T., 2000).Singing male white-handed gibbon (Hylobates lar, Zoo

Rapperswil)

Another specialization is the occurrence of duet singing in all gibbons with the exception of H. klossii and H. moloch (Geissmann 1993). Duets are mostly sung by mated pairs . Typically, mates combine their repertoire in relatively rigid, more or less precisely timed vocal interactions to produce well-patterned duets.http://www.gibbons.de/main/sound/sounds/08conc_sounds/coDuett94b3270.wav

Vervet monkeys

Vervet monkey alarm calls

• Vervet monkeys produce acoustically distinct alarm calls in response to

different classes of predator

– Large cats (e.g. leopard, cheetah)

– Birds of prey (e.g. martial eagle, crowned hawk eagle)

– Snakes (e.g. pythons, mambas)

• Hearing the leopard call, the members of the troupe run up to the top of

the nearest tree

• Hearing the eagle call, the members of the troupe run into a nearby bush

or under the lower branches of a nearby tree

• Hearing the snake call, the troupe of vervets all stand up on their hind

legs in the open and look around on the ground

Conclusion:communicate with a group. Animal communication is more based on the need to warn of danger or to describe the location of food, it is more of a necessary means of survival. Human language however adopts these characteristics of needing communication for survival but adds to them to form a language system that is both needed for survival but is also a social communication device, that is used spontaneously, something an animal does not especially require in order to survive in the animal world.(Tomasello and Call 1997).

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Hauser, M. D. (1996) The evolution of communication., Cambridge, MIT Press

Owings, D. H. & Morton, E. S. (1998) Animal vocal communication: A new approach, Cambridge, Cambridge University Press

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