2. Tierpsychol., 69, 166-167 (1985) @ 1985 Verlag Paul Parey, Berlin und Hamburg ISSN 0044-3573 / Intercode: ZETIAG

Commentary

Department of Environmental, Population and Organismic Biology, University of Colorado, Boulder

Evolutionary Perspectives of Behavioral Development

By MARC BEKOFF

ROPER’S (1984, Z. Tierpsychol. 65, 166-167) recent review of the vol- ume “Behavioral development: The Bielefeld interdisciplinary project” is very informative and contains some useful food for thought for scientists interested in the ontogeny of behavior. H e correctly stresses that development is a life- long process and that careful observation must precede rampant speculation and theorizing.

ROPER also claims that “. . . behavioural development has yet to acquire a coherent theoretical framework. . .” (p. 166) and that “Behavioural devel- opment may still be groping for a synthesis. . .” (p. 167). I think he is correct, and that these problems are present because of the interest in development that is shown by scientists in numerous and diverse disciplines. But I also believe that there is a relatively simple and straightforward remedy. Behav- ioral development, like all other biological processes, can, and should, be viewed from an evolutionary perspective. This point of view is applicable to all aspects of behavior, and provides a theoretical and synthetic framework in which a wide variety of ontogenetic processes can be understood (LIEBER- MAN 1984; BEKOFF and BYERS 1985). The evolutionary perspective does not lessen the importance of studying infants as infants, but rather, it stresses that selection operates on individuals of all ages, not only on reproductive adults, and that young animals need to be able to adapt to numerous and diverse demands when they are young as well as when they are more independent and mature. It also stresses, as ROPER notes, “. . . that a developmental perspective necessarily encompasses adulthood, and that the study of development must be longitudinal” (p. 167).

By using an evolutionary perspective as a focal point, (1) seemingly diverse behaviors can be viewed in a more unified manner, ( 2 ) neurobiology and behavior can be more neatly packaged together, and (3) central issues involving discontinuity and continuity, learning, and behavioral flexibility

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Erolutionary Perspectives of Behavioral Ihvelopment 167

can be discussed from a common point of view. Also, prenatal and postnatal ontogeny, including maturation and senescence, can be analysed along a con- tinuum. Thus, behavioral patterns .issociated with these overlapping stages of development can be understood to be the result of selective forces that exert themselves on individuals of all ages. Finally, and of great importance, an evolutionary perspective lends itself nicely to comparative and life history analyses of development (BEKOFF and BYERS 1985).

When applied carefully, an evolutionary analysis and explanation of behavioral development will broadcn our horizons about ontogeny. Although it can be argued that all behavior may not be adaptive, we will never be able to estimate reliably how much is or is not until we gather pertinent infor- mation on the earliest emergence of the diverse behavioral phenotypes that are displayed by young animals, including embryos and fetuses. In summary, one solution to the dilemma that ROPE.R points out is to adopt an evolutionary perspective that permits scientists with diverse backgrounds to confront the extremely important and interesting problems with which developmental studies are concerned, from a common point of view.

Literature Cited

BEKOFF, M., and J. A . BYERS (1985): The development of behavior from evolutionary

LIEBERMAN, P. (1984): The Biology .uid Evolution of language. Harvard Univ. Press, and ecological perspectives. Evol. Biol. 19, i n press.

Cambridge, Mass.

Author’s address: Marc BEKOFF, Ikpar tment of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, Colorado 80309, USA.