Interactions: The Biological Context of Social Systems

by N. Eldredge and M. Grene, Columbia University Press, 7992. $46.00 hbk 1242 pages) ISBN 0 231 07946 X Aristotle argued that ‘as each of the parts of the body, like every other in- strument, is for the sake of some purpose, viz. some action, it is evi- dent that the body as a whole must exist for the sake of some complex action”. His reasoning remains valid, even if the complex action modern biologists have in mind is more likely to be ultimate reproductive success than his ultimate cause. As an example, the foraging for food by a Drosophila larva and an adult’s al- location of materials to gametes are different sorts of immediate actions, but the complex action to which they are both subordinate is repro- ductive success. For any attribute of any organism to be an adaptation, it is necessary and sufficient that it normally contribute to this complex action. Reproductive success thus becomes the final conceptual device of adaptationist explanation. Eldredge and Grene reject this sort of reasoning, which they label ‘ultra- Darwinism’. Only explicitly procrea- tive functions, not those related to nutrition and survival, should be seen as for the sake of reproduction. Evolutionary theory would be im- proved by a consistent conceptual separation of the reproductive from the economic, a term they prefer to ecological in this context. Woolfenden and Fitzpatrick* are taken to task for explaining territoriality in the Florida scrub jay (Aphelocoma coerulescens) by its contribution to reproduction in a future season or future year, because most of the time it merely enhances feeding. The two categories of adaptation are viewed as important because they give rise to the two different hierarchies of biological organiz- ation. Economic adaptations underlie an ecological hierarchy that ranges from the local population to the glo- bal ecosystem. Reproductive adapta- tions underlie a genealogical hierar- chy from the local deme through ever more inclusive clades to the planetary biota. The authors want more attention to be given to the his- tory of communities and ecosys- tems, although they emphasize that such entities do not evolve or adapt in the same sense as mendelian popu- lations They state that all reproduc- tive adaptations evolve by sexual selection and maintain that this is Darwin’s original concept and is widely acceptable to current workers. Thus, they attribute a vixen’s defense of her cubs to sexual selection. The book contains some annoying errors and counter-factual impli- cations. It gives the impression, in discussing both genealogical and ecological hierarchies, that the population structures and develop- mental patterns of higher terrestrial animals and plants are the very gen- eral rule. This is surprising, in view of Eldredge’s expertise on a major marine group. It downplays the great variation shown by life history pat- terns and ontogenetic niche shifts. It maintains that cannibalism is rare in nature and largely limited to filial in- fanticide. Recent field work3-6 gives quite a different impression. Large piscivorous fishes can carry canni- balism to the point of multilevel food chains within a single population’. Discussions of insect eusociality make it dependent on the special genetic relationships in monandrous haplodiploid colonies and ignore the reduced kinship levels in multiply inseminated or multiple- queen colonies. They propose a close genetic parallel between insect colonies and those of asexually pro- duced bryozoans and siphonophores and then contrast these with mam- malian genetic and social systems. They thereby ignore the fact that hymenopteran egg production is just as meiotic as mammalian, and therefore provides for within-colony genetic conflict. They ignore termites. I have many conceptual conflicts with Eldredge and Grene that are re- ally matters of scientific opinion and philosophy. They see speciation (origin of new mate-recognition sys- tems) as the crucial event in biotic evolution. I prefer a broader concept of cladogenesis. I agree with their assessment of the importance of stasis in the fossil record, but not with their explanation of it. Most the weaknesses they find in contemporary evolutionary thinking I regard as strengths. These are not points to belabor here, especially since I recently belabored them elsewhere*. Despite the ways I think that Eldredge and Grene are in error, I can recognize that they make many valid and original points. They provide a well-reasoned discussion of the complex topic of biological (and in- stitutional) individuality and related phenomena of asexually generated colonies. They take the reader through a stimulating and informative historical tour from Descartes through Weismann to recent work by Buss, Sober and many others. They propose what strike me as promising ideas on human sociality and its relationship to language capability and our spe- cial brand of altricial development.