ABSTRACT
This conclusion presents some closing thoughts on the concepts covered in the preceding chapters of this book. The book focuses on experimental data and theoretical considerations which suggested that the cradleboard might constitute a perturbation in the environment of Navajo mother–infant interaction. It argues that the process of adaptation is best seen in terms of hierarchically interconnected environmental tracking systems and that the process of adaptation is not limited to changes in the genotype over generations but that it includes the most immediate behavioral responses of individuals to environmental perturbations. The book describes group differences in behavior may be observed because of simple group differences in the distribution of nongenetic factors causing indivdual differences. It shows that levels of irritability in newborn Navajo infants were related to their mothers' blood pressure during pregnancy, reviews other studies showing similar blood pressure effects on irritability.
