Variation and cultural transmission of sperm whale (Physeter macrocephalus) codas
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"Communicative interactions are the essence of all animal societies, so it is appropriate to examine communication as a way to gain insight into social structure" (Baker, 1982) |
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The link between communication signal and social structure is particularly clear in cetaceans; whether signals are individual, group or population specific often reflects the social system of the species in question (Tyack, 1986; Tyack and Sayigh, 1997). For example, bottlenose dolphins (Tursiops truncatus) show individual-specific tonal "signature whistles" (Caldwell et al., 1990), and live in a fission-fusion society within which associations between individuals are labile in the short term, but can form the basis of long lasting relationships (Wells et al., 1987). "Resident" killer whales (Orcinus orca) show group-specific pulsed call repertoires (Ford, 1991), and live in highly stable matrilineal groups (Bigg et al., 1990). The song of the humpback whale (Megaptera novaeangliae) varies between populations (Winn et al., 1981), as do the low frequency pulses of fin whales (Balaenoptera physalus) (Thompson et al., 1992); both of these species show little stability in their social relationships (Whitehead and Carlson, 1988; Clapham, 1996). Thus cetacean vocalisation is an important aspect of their underlying population and social structure.
Learning appears to have a strong role in the development of vocal patterns in cetaceans, more so than has currently been found in any other mammal group outside humans (Janik and Slater, 1997; McCowan and Reiss, 1997); where investigated, this appears to take the form of social learning (McCowan et al., 1998; Heimlich-Boran and Heimlich-Boran, in press). Behaviour or information affecting behaviour that is acquired through social learning and passed on to other individuals is a broad definition of culture (Bonner, 1980; Mundinger, 1980; Boyd and Richerson, 1985; Aoki, 1991). When that behaviour or information is passed down from parent to offspring through learning then it is said to be vertically transmitted (Feldman and Laland, 1996). Vertical cultural transmission can have important evolutionary consequences because the transmitted information or behaviour can affect the biological evolution of a species (Russell and Russell, 1990; Laland, 1992). While theory suggests that such vertical transmission of behavioural traits should be a widespread phenomenon, it is in fact rarely documented outside humans (Laland et al., 1996). However, vocal behaviour is one area where it does occur; for example, social learning of songs in the true songbirds (Oscines) is among the few instances of vertical cultural transmission outside humans (Mundinger, 1982; Slater, 1986). In the Cetacea, we find one of even fewer examples of vertical transmission with high stability: the traditions in group-specific call repertoires of "resident" killer whales (Ford, 1991). Thus cetacean vocalisations can also offer insight into questions of animal culture.
I propose to investigate variation and cultural transmission in the coda vocalisation of sperm whales (Physeter macrocephalus) in the context of their population and social structures. More specifically, I intend to test the hypothesis that sperm whale coda repertoires are group-specific, attempt to quantify rates of change in coda repertoire over different time scales and attempt an assessment of functionality for codas and hence potentially for coda repertoires.
Animal Culture
Culture has been defined many times in subtly different ways; the table below gives some examples, mainly from the biological literature. From this table, culture can be broadly defined as behaviour or information affecting behaviour that is transmitted between individuals by non-genetic means, namely social learning.
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lrendell@is2.dal.caSome Definitions of Culture
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SOURCE |
DEFINITION |
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Aoki (1991) |
"the transfer of information between individuals by imitative or social learning" |
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Bonner (1980) p163 |
"I have defined culture as the transfer of information by behavioural means" |
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Boyd and Richerson (1985) p33 |
"Culture is information capable of affecting individuals' phenotypes which they acquire from other conspecifics by teaching or imitation" |
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Feldman and Laland (1996) |
"culture is treated as shared ideational phenomena (ideas, beliefs, values, knowledge)" |
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Heyes (1993) |
"a subset of traditions in which the focal behaviour has been formed through the accumulation of modifications through time" |
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Kummer (1971) p13 |
"cultures are behavioural variants induced by social modification, creating individuals who will in turn modify the behaviour of others" |
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Mundinger (1980) |
"culture is a set of [behavioural] populations that are replicated generation after generation by learning" |
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Nishida (1987) |
"Cultural behaviour is thus defined here as behaviour that is (a) transmitted socially rather than genetically, (b) shared by many members within a group, (c) persistent over generations and (d) not simply the result of adaptation to different local conditions." |
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Russell and Russell (1990) |
"The culture of a society may be defined as behaviour common to a substantial proportion of its members, socially transmitted within and between generations" |
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Slater (1986) |
"cultural transmission is the phenomenon whereby features of behaviour pass by learning from one individual to another" |
References
Aoki, K. (1991) Some Theoretical Aspects of the Origin of Cultural Transmission. Pages 439-449 in S. Osaura and T. Honjo (Eds.) Evolution of Life : Fossils, Molecules and Culture. Springer-Verlag, Tokyo.
Baker, M. C. (1982) Genetic population structure and vocal dialects in Zonotirchia (Emberizidae). Pages 209-232 in D. E. Kroodsma and E. H. Miller (Eds.) Acoustic Communication in Birds. Volume 2 : Song Learning and it's Consequences. Academic Press, London.
Bigg, M. A., Olesiuk, P. F., Ellis, G. M., Ford, J. K. B. and Balcomb, K. C. (1990) Social organization and genealogy of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington State. Rep. int. Whal. Commn (Special Issue) 12:383-405.
Bonner, J. T. (1980) The Evolution of Culture in Animals. Princeton University Press, Princeton, NJ.
Boyd, R. and Richerson, P. (1985) Culture and the evolutionary process. Chicago University Press, Chicago.
Caldwell, M. C., Caldwell, D. K. and Tyack, P. L. (1990) A review of the signature whistle hypothesis for the Atlantic bottlenose dolphin, Tursiops truncatus. Pages 199-234 in S. Leatherwood and R. R. Reeves (Eds.) The bottlenose dolphin:recent progress in research. Academic Press, San Diego.
Clapham, P. J. (1996) The social and reproductive biology of humpback whales : An ecological perspective. Mammal Rev. 26:27-49.
Feldman, M. W. and Laland, K. N. (1996) Gene-culture coevolutionary theory. Trends Ecol. Evol. 11:453-457.
Ford, J. K. B. (1991) Vocal traditions among resident killer whales (Orcinus orca) in coastal waters of British Columbia. Can. J. Zool. 69:1454-1483.
Heimlich-Boran, J. R. and Heimlich-Boran, S. L. (in press) Social learning in cetaceans: hunting, hearing and hierarchies. Symp. Zool. Soc., Lond. 73.
Heyes, C. M. (1993) Imitation, culture and cognition. Anim. Behav. 46:999-1010.
Janik, V. M. and Slater, P. J. B. (1997) Vocal learning in mammals. Advances in the Study of Behavior 26:59-99.
Kummer, H. (1971) Primate Societies : Group techniques of ecological adaptation. Aldine-Atherton Inc., Chicago.
Laland, K. N. (1992) A theoretical investigation of the role of social transmission in evolution. Ethol. Sociobiol. 13:87-113.
Laland, K. N., Richerson, P. J. and Boyd, R. (1996) Developing a theory of animal social learning. Pages 129-154 in C. M. Heyes and B. G. Galef Jr. (Eds.) Social learning in animals : The roots of culture. Academic Press, San Diego.
McCowan, B. and Reiss, D. (1997) Vocal learning in captive bottlenose dolphins : a comparison with humans and non-human animals. Pages 178-207 in C. T. Snowdon and M. Hausberger (Eds.) Social influences on vocal development. Cambridge University Press, Cambridge.
McCowan, B., Reiss, D. and Gubbins, C. (1998) Social familiarity influences whistle acoustic structure in adult female bottlenose dolphins (Tursiops truncatus). Aquat. Mamm. 24:27-40.
Mundinger, P. C. (1980) Animal cultures and a general theory of cultural evolution. Ethol. Sociobiol. 1:183-223.
Mundinger, P. C. (1982) Microgeographic and macrogeographic variation in the acquired vocalizations of birds. Pages 147-208 in D. E. Kroodsma and E. H. Miller (Eds.) Acoustic communication in birds. Volume 2. Academic Press, New York.
Nishida, T. (1987) Local Traditions and Cultural Transmission. Pages 462-474 in B. B. Smuts, D. L. Cheney, R. M. Seyfarth, R. W. Wrangham and T. T. Struhsaker (Eds.) Primate Societies. University of Chicago Press, Chicago.
Russell, C. and Russell, W. M. S. (1990) Cultural Evolution of Behaviour. Neth. J. Zool. 40:745-762.
Slater, P. J. B. (1986) The cultural transmission of bird song. Trends Ecol. Evol. 1:94-97.
Thompson, P. O., Findley, L. T. and Vidal, O. (1992) 20-Hz pulses and other vocalizations of fin whales, Balaenoptera physalus, in the Gulf of California, Mexico. J. Acoust. Soc. Am. 92:3051-3057.
Tomasello, M. (1994) The question of chimpanzee culture. in R. W. Wrangham, W. C. McGrew, F. B. M. de Waal and P. G. Heltne (Eds.) Chimpanzee Cultures. Harvard University Press, Cambridge, Massachusetts.
Tyack, P. (1986) Population biology, social behavior and communication in whales and dolphins. Trends Ecol. Evol. 1:144-150.
Tyack, P. L. and Sayigh, L. S. (1997) Vocal learning in cetaceans. Pages 208-233 in C. T. Snowdon and M. Hausberger (Eds.) Social Influences on Vocal Development. Cambridge University Press, Cambridge.
Wells, R. S., Scott, M. D. and Irvine, A. B. (1987) The social structure of free-ranging bottlenose dolphins. Pages 247-305 in H. H. Genoways (Ed.) Current Mammalogy. Volume 1. Plenum Press, New York.
Whitehead, H. and Carlson, C. (1988) Social behaviour of feeding finback whales off Newfoundland: comparisons with the sympatric humpback whale. Can. J. Zool. 66:217-221.
Winn, H. E., Thompson, T. J., Cummings, W. C., Hain, J., Hudnall, J., Hays, H. and Steiner, W. W. (1981) Song of the humpback whale - Population comparisons. Behav. Ecol. Sociobiol. 8:41-46.