The classic debate is a debate of opposites; the new debate is one of chickensand eggs. On the one hand, the classic debate simply has no resolution becausenativists and empiricists cannot even agree on a dependent variable, much less acommon methodology. The new debate, on the other hand, is not a dead end; itmight just have a resolution. It won't be either the chicken or the egg,however, but it might just be the chick.

This chapter reviews, in turn, the two participants in the new debate,evolutionary psychology and developmental systems theory, and then we see wherean integration of the two might just become possible.

Evolutionary Psychology

Most theories of human development focus on proximal variables, ones concurrentwith the developmental events themselves or in the very recent past of theindividual. This is certainly true of the nativists and empiricists of theclassic debate. Evolutionary psychologists see things differently, verydifferently. Their focus is on the distal antecedents of our behavior anddevelopment, causes that are depicted as taking place a very, very, very longtime ago.

There is no one theorist who ideas represent evolutionary psychology (EP), asmight be the case if we were discussing Piaget or Freud. Rather, there are manypeople working within this tradition or perspective. Nevertheless, the mostconsistent and well-developed exposition of EP comes from the series of paperswritten over a number of years by John Tooby and Leda Cosmides (Cosmides andTooby n/d; Tooby and Cosmides 1997; Cosmides and Tooby 2001; Tooby et al. 2003;Tooby and Cosmides 2005). I first summarize the model by reviewing their workand then present two variations on the model, one moving EP closer todevelopmental behavior genetics and the other closer to developmental systemstheory (DST).