Integrating developmental psychology, dynamic systems theory and evolutionary theory

Results 2004

We have presented a poster at the annual meeting of the Human Behavior and Evolution Society. The poster addressed the question: “Should we use the adaptationist or the developmental approach in evolutionary psychology?” The abstract of this poster was:
There has been a recent debate in Psychological Bulletin about whether the adaptationist, neo-Darwinian approach or the evolutionary developmental (evo-devo) approach is most appropriate when applying evolutionary principles to psychology. Wagner (2000) argues that both approaches are relevant to biology, depending on the subject of study. When the variable under study is quantitative, for example, in the case of the common female-male sex ratio of 1:1, the explanation of the phenomenon can be given in terms of natural selection. Developmental mechanisms play no role. However, when the variable under study changes qualitatively, for example, when we want to explain the origin of eyespots on butterfly wings, we have to refer to developmental mechanisms that caused the qualitative change. Saying that eyespots enhance survival chance does not explain the origin of the eyespots. We argue that the same line of reasoning can be used in psychology. The adaptationist approach is more suitable for subjects in social p sychology like sex differences in mate choice and sexual strategies. Here the variable is mostly quantitative, for example the number of sex partners one desires. Natural selection explains the sex difference. However, the evo-devo approach is more suitable for answering the main questions in developmental psychology. For example, if we like to know whether there are stages in development or not, we have to look for the mechanisms behind development. Evo-devo biology provides interesting models that can also be applied to developmental psychology. The adaptationist approach does not offer these models.

A first manuscript has been submitted for publication. This manuscript provides a broad theoretical overview of the question whether evolutionary psychology can be useful in answering basic questions in developmental psychology. We formulated five basic questions in developmental psychology: 1) Do children develop domain-general or domain-specific mechanisms? 2) Are there stages in development? 3) What is the influence of nature and nurture on development? 4) Is the development of intelligence stable or plastic? 5) How do individuals differ? We argue that the framework of evolutionary psychology, that is, the adaptationist framework with its strong emphasis on natural selection, is not sufficient in order to be useful to answer these basic questions. We argue that we need to broaden the view of evolutionary psychology with the framework of evolutionary developmental biology and dynamic systems theory in order to reach a useful metatheory for developmental psychology. We give both theoretical arguments and exa mples to provide evidence for this point of view.

A second manuscript is in progress. This manuscript will be specifically about the basic question “How do individuals differ?”. On the one hand, evolutionary psychology emphasizes universal psychological characteristics of human begins. They argue that the basic architecture of the human mind is the same for every human being. Individual genetic differences must be small and rather meaningless. On the other hand, behavior genetics studies howmuch of the variance in psychological characteristics can be explained by genetic influence. Behavior genetics shows that genetic individual differences are large. How can these to fields, that both deal with the basic architecture, that is, the genes, of the human mind, be reconciled? We will show that evolutionary developmental biology and dynamic systems theory provide models that explain both the existence of basic characteristics with hardly any genetic variance, and the existence of characteristics with large amounts of genetic variance.

A third manuscript in progress will be about a specific model of evolutionary developmental biology and dynamic systems, that deals with three of the basic questions in developmental psychology, that is, domain-general vs domain-specific mechanisms, stagewise vs nonstagewise development, and plasticity of intelligence. This model will be used to simulate the differences in development between identical and nonidentical twins.