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1 July 2008 Wasp Social Evolution: But Don't Ask “Why?”
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James Hunt's recent book The Evolution of Social Wasps is an unusual contribution to the social-insect literature. On the one hand, it presents a great deal of detailed and useful information on the biology of social wasps. Thus, the book will be an important point of reference for anyone wanting to learn more about wasps. On the other, the author sees things from an unusual viewpoint with respect to W. D. Hamilton's theory of inclusive fitness. This is a theory that many people, but certainly not Hunt, feel has greatly enhanced our understanding of insect eusociality, which is characterized by individuals (workers) that reproduce very little or not at all and devote their lives to helping others—usually their mother and father—to reproduce more. The book also presents Hunt's own ideas concerning the evolution of worker behavior.

The book is arranged in three sections. The first (“History”) puts the social wasps in their phylogenetic context with chapters narrowing in from the Hymenoptera as a whole to “Paper Wasps and Vespines,” with the final chapter focusing on the phylogeny of the Vespidae, the family containing almost all the eusocial wasps, and traits that influence sociality in this group.

Hunt introduces the second section (“Dynamics”) by stating his belief that “many, perhaps most, of the mysteries of hymenopteran sociality might be resolved if investigators would ‘follow the protein’.” Unsurprisingly, the following chapters—“Individuals,” “Colonies,” and “Populations”—emphasize food and feeding and their effects on things such as the body size of the reared individuals. The final chapter in this section, “The Dynamic Scenario of Social Evolution,” is perhaps the most important in the book because it presents what Hunt probably feels is his greatest contribution to the study of wasp evolution: a mechanistic scenario in which individuals in social groups forgo reproduction on the basis of traits involved in controlling the reproductive physiology of noneusocial wasps with two generations per year.

The third section (“Paradigm Lost—and Found?”) completes the book. I am not sure whether it will prove to be usefully controversial and hence stimulate a debate, or whether it will simply be ignored because its stance is uncompromising––Hunt makes no attempt to build bridges. Inclusive fitness theory and behavioral ecology get little credit or sympathy, and perhaps not surprisingly, Hunt proposes his own “general conceptual framework to study sociality and a specific research agenda for the future study of hymenopteran social evolution.”

Hunt dismisses the widely accepted idea that it is possible to profitably study both “how “ and “why” questions in animal behavior, with the latter questions solidly in a subservient role: “Why questions, do, indeed, stimulate enquiry, but they should be used appropriately. They should be used to sketch out outlines of hypotheses. Those hypotheses then can be formalised, and rigorous tests can be designed to attempt falsification of those hypotheses. Those tests should be grounded in phylogeny and/or mechanisms. Once the data are in, they will address questions of how. Only then may interpretation (perhaps!) be couched in terms of why” (p. 193).

Important insights into reproduction, conflict, and conflict resolution within insect societies that have arisen from the application of inclusive fitness theory are not only dismissed or effectively ignored, they are also seen as likely to cause errors in judgment: “An investigator studying ‘investment ratios’ is narrowly constrained by preconceptions, whereas an investigator studying patterns of reproduction is less constrained. An investigator studying ‘worker policing’ will look for only a limited range of causes and explanations, whereas broader inquiry and interpretation are open to an investigator studying oophagy.… ‘Oophagy’ is a term reserved to science, and it has no use or implied meaning in human culture. Thus it can be studied in objective neutralism” (pp. 187–188). In fact, worker policing, in which workers prevent each other from reproducing, is mechanistically diverse. Worker policing also consists of more than egg eating alone (occurring through aggression in some contexts), so anyone following Hunt's recommendation would actually be more, not less, narrowly constrained. On page 193 Hunt quotes a colleague as saying “the problem is not with the question; the problem is satisfaction with the answer!” Clearly, Hunt finds little satisfaction with the kinds of insights that inclusive fitness theory can provide, and little of value in “why” questions.

In conclusion, the book presents the evolution of social wasps from the viewpoint of a person who combines decades of experience in studying wasps with very clear views of what is and is not interesting to study, and how that study should be conducted. If Hunt had been a 17th-century physicist, he would have had no problem with Tycho Brahe, but he probably would have objected somewhere between Kepler and Newton.

Francis L. W. Ratnieks "Wasp Social Evolution: But Don't Ask “Why?”," BioScience 58(7), 662-663, (1 July 2008).
Published: 1 July 2008

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