The authors of the article The Reconstruction of Hominid Behavioral Evolution Through Strategic Modeling propose the use of strategic modeling to be able to better reconstruct the behavioral evolution of early human ancestors. They make a distinction between what they call referential models and conceptual models. Referential models are those that use stand ins for the real thing that researchers are actually interested in because, like in the case of hominid evolution, they cannot be directly studied or it would be unethical to do so (as in the case of medical research). So a researcher may propose that the key to understanding hominid behavioral evolution is an understanding of, for example, baboon behavior because it is argued that early humans shared a similar habitat to modern-day baboons. The problems with this approach are that it is difficult to choose any particular species of modern animal or even modern human hunter and gatherer populations as stand-ins for the ancient and unique animals that existed early in our evolution. The authors argue that there is in fact no reason to believe that a modern animal is a good equivalent for an extinct one and that use of such referential models is mostly arbitrary.
A conceptual model on the other hand is essentially a theory that among many other things has “elements that are well-defined and easily operationalized…the assumptions on which it is based are validated…it makes potentially falsifiable predictions” and can explain a wide range of phenomena with just a few major elements (Tooby and DeVore 1987, 185). Examples of good conceptual models are Newton’s mechanics and Darwin’s theory of natural selection (Tooby and DeVore 1987, 186). The authors argue that there is a need to develop a strong conceptual model to add to our understanding of hominid behavioral evolution.
“Strategic modeling” as used by the authors is meant to “cover the construction of conceptual models of primate and hominid behavior based on our understanding of 1) the genes as a unit of selection, and 2) animals as shaped to behave as strategists promoting their inclusive fitness” (Tooby and DeVore 1987, 189). Basically, the argument is that the laws of evolution have always functioned in the same way so that every species, modern or extinct, is a result of these laws. If we can figure out the circumstances in which hominids evolved, we can at least narrow down the possible traits of these animals. With each subsequent find or discovery, new information can be integrated into the model to further narrow the possibilities so that eventually we will have a clear picture of what our different hominid ancestors were like. So figuring out human evolution and the stages that our direct ancestors went through, is like plugging in what is known (data) into an equation (strategic model) in order to get a range of possibilities. This approach, the authors argue is sorely needed in order for the discipline to be a true science (Tooby and DeVore 1987, 237).
First you need a conceptual framework. This framework is what the authors call “the principles of strategic modeling” and they list 25 of them. These are the rules that are meant to help researchers to construct strategic models that make sense. The authors then use these rules to find fault with many of the major theories/models in evolutionary anthropology. For example, the “woman the gatherer hypothesis” that proposes that the key feature that propelled early hominids onto the evolutionary track that lead to modern humans and distinguished them from the pongids was the gathering of vegetable materials. The authors find fault with this theory because it does not adequately explain differences between the great apes and man, since apes also gather plant materials, or the ability of humans to survive in locations where plant sources of food are scarce, such as the arctic. Additionally, this theory does not explain why women would bring gathered food back to males who apparently did not do all that much (Tooby and DeVore 1987, 212-215). These criticisms are valid and make sense. In fact, once you put it in the conceptual framework, the theory seems almost nonsensical. Therefore strategic modeling is very useful in order to be able to sort out all of the very complicated issues that are intrinsic to the study of human evolution. Without a concrete set of guidelines to match data and hypotheses to, it is easy to get confused or forget to include some of the major principles of biology, ecology or evolution.
Another interesting point is that there is no evidence that throughout our long evolutionary history, hominids progressed in a linear fashion. The authors argue that evolution is driven by the environment and so every shift in ecological pressure would change what was selected for as well as the strategies used by hominids to survive. So there was no steady and gradual progression from ape to man but it happened in spurts, sometimes with complete reversals and was a much messier and complicated process than has been imagined (Tooby and DeVore 1987, 202-207). This makes sense because our evolution into our present form was not the “goal,” there is no ultimate “goal” of evolution in terms of the forms an organism should take, there is only the “goal” to increase an organism’s fitness in a particular environment. So if the environment changes so must the traits that are selected for, even if it means “moving backward.” For example, if evolutionary pressures selected for a larger brained animal and then the environment changed so that a larger brain was actually a disadvantage, evolution would select for a smaller brained animal to adapt to these new conditions. If the modern descendent of this animal has a large brain, this could be viewed as a regression, or could be grounds for dismissing that particular relative from the family tree. Therefore, we must view evolution as a series of distinct stages because anything else would be misleading about the nature of human evolution. “An extinct species should not be viewed as a crude, imperfect version of a living form, but as interesting in its own right, just as adapted to its own archaic present as any living animal. Each morphologically distinguishable fossil species needs to be characterized in terms of its distinctive interlocking system of adaptations” (Tooby and DeVore 1987, 204).
Tooby, John and Irven DeVore.
1987. The Reconstruction of Hominid Behavioral Evolution Through Strategic Modeling. Pages 183-237 in W.G. Kinzey, (Ed). The Evolution of Human Behavior: Primate Models. State University of New York Press, Albany.