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Open Access Publications from the University of California


The International Journal of Comparative Psychology is sponsored by the International Society for Comparative Psychology. It is a peer-reviewed open-access digital journal that publishes studies on the evolution and development of behavior in all animal species. It accepts research articles and reviews, letters and audiovisual submissions.

Volume 19, Issue 2, 2006


Identity of Comparative Psychology: Its Status and Advances in Evolutionary Theory and Genetics

Recent developments in theories in evolution, development and comparative psychology indicate that a redefinition of comparative psychology may be useful. A brief review of the marginalization of the scientific and academic identity of comparative psychology indicates the need to integrate contemporary thinking in evolutionary biology, genomics and developmental theory. Schneirla’s concept of integrative levels, punctuated equilibrium and exaptation theory elaborated by Eldredge, Gould, and Vrba, and advances in genomics (e.g., retrotransposon function) would be helpful in countering the marginalization of comparative psychology. A provisional redefinition is offered for discussion by those who identify themselves as members of the discipline; comparative psychology is the science of the elucidation of similarities and differences in the evolution and development of the activity of all species to illume the processes by which their activity contributes to the beneficence of their relationship to the abiotic and biotic aspects of the environment. Comparative psychology as a “science” emphasizes methods of investigation relating to all levels of the integration of processes that are relevant to the evolution and development of the activity of all species.

Role of Development in Evolutionary Change: A View from Comparative Psychology

Evolution has come to be increasingly discussed in terms of changes in developmental processes rather than simply in terms of changes in gene frequencies. This shift is based in large part on the insight that since all phenotypic traits arise during ontogeny as products of individual development, a primary basis for evolutionary change must be variations in the patterns and processes of development. Comparative psychology has a unique role to play in defining and describing these developmental dynamics, in large part because its specific aims and purposes are not well represented in other sub-disciplines within the life sciences. These include an empirical concern with the developmental and ecological dynamics contributing to behavioral and psychological functioning (especially in terms of degrees of flexibility or malleability) and the significant role of behavior in the evolutionary process (particularly in generating novel phenotypes). Comparative psychologists have provided converging evidence supporting the view that shifts in behavior brought about by changes in the environment and the resulting changes in the activity of the organism can lead to variations within and across generations in morphology and physiology, providing the engine for generating evolutionary change.

Studying Evolution in Action: Foundations for a Transgenerational Comparative Psychology

The gene centered framework of the modern evolutionary synthesis serves to constrain the contributions to evolutionary knowledge that can be gained from comparative studies of animal development. Contrary to this position, a case is made that understanding the dynamics of ontogenetic processes across generations can illuminate processes of evolution. Examples are provided that show how alterations of developmental contexts in one generation influence patterns of development in subsequent generations. The conceptual foundations and implications of a transgenerational orientation to studying animal development are discussed. By adopting a transgenerational approach, comparative psychologists can study evolutionary processes in action and thus play a more prominent role in discussions of evolution.

Psychology is a Developmental Science

In this paper we argue that psychology should be understood as a developmental science, and we place the discipline squarely in the realm of the natural sciences. The case is made that scientific progress in psychology has been (and still is) impeded by prolonged misadventures down conceptual dead ends such as biological reductionism, the nature/nurture debate, evolutionary psychology, and the persistent insistence on emphasizing dependent variables that defy observation and measurement, such as “mind” and cognitive modules. We take issue with the behavior geneticist’s approach to psychology while making the case that many psychologists and biologists today seem wholly unaware of many of the most recent experimental results in the area of molecular genetics, especially as they relate to development. We propose that such results, as well as those in the area of nonlinear dynamics, support a developmental systems perspective of psychology emphasizing the epigenetic nature of development as well as the importance and reality of emergent properties in psychology in particular and science in general. Whereas we do not dismiss the significance of biological processes for a full appreciation of behavioral origins, we understand biology to merely be one of many participating factors for psychology.

Social Traditions and the Maintenance and Loss of Geographic Variation in Mating Patterns of Brown-Headed Cowbirds

Considerable geographic variation often exists in behaviors of different populations of a species. Of key interest are the mechanisms generating this variation, and the impact this variation may have on gene flow between two populations. Here, we review two sets of studies of brown-headed cowbirds, Molothrus ater, indicating that the social background of an individual can impact its ability to court, pair, and mate with individuals of one behavioral tradition/population relative to individuals of another behavioral tradition/population. The first studies involved two populations with extant differences in mating behaviors and found that young cowbirds of one population that interacted over ontogeny with members of a behaviorally-distinct population developed courtship behaviors and mating patterns similar to members of that ‘foster’ population. The second set of studies tested the possibility of generating distinct systems of mating behavior within one population and found that young cowbirds that interacted over ontogeny with different age-structured social groups developed effectively distinct mating patterns. Thus, social traditional processes in cowbirds can create, maintain, or dissolve population-level differences in courtship and communication. This work highlights the power of the social environment to act as a structuring ecology for behaviors fundamental to reproductive success.

Role of Peers in Cultural Innovation and Cultural Transmission: Evidence from the Play of Dolphin Calves

Observations of the spontaneous play behaviors of a group of captive bottlenose dolphins ( Tursiops truncatus ) revealed that each individual calf’s play became more complex with increasing age, suggesting that dolphin play may facilitate the ontogeny and maintenance of flexible problem solving skills. If this is so, play may have evolved to help young dolphins learn to adapt to novel situations. Novel play behaviors were more likely to be produced by dolphin calves than by adults, demonstrating that calves were the main source of innovative play behaviors in the group. Calves were also more likely to imitate novel play behaviors first produced by another dolphin, suggesting that calves contribute significantly to the spread of novel behaviors within a group. All in all, these data suggest that peers may be important catalysts for both cultural innovation and cultural transmission, and that the opportunity to interact with peers may enhance the effect play has on the emergence of flexible problem solving skills.

Ordering and Executive Functioning as a Window on the Evolution and Development of Cognitive Systems

We summarize some key features of our comparative and developmental programme at Edinburgh with particular reference to serial ordering and executive control as a window on the growth of cognitive competences in both evolution and development. Based on research on relational rather than associative learning mechanisms, we first argue that nonhuman primates share some core conceptual representations supporting semantic and rational development in humans. Reviewing recent findings from comparative work on seriation and classification, we also show that non-human primates can use ordering mechanisms similar to those that emerge during human development. From theses analyses, we argue that key features of thought and language have strong evolutionary precursors.