* Consider “stranger anxiety” as a candidate psychological adaptation. Its function is to motivate the infant to
recoil from potentially dangerous humans and to maintain close proximity to caregivers, thereby avoiding hazards that strangers might pose. Stranger anxiety possesses a number of well-articulated design features. It shows universality, emerging in infants in all cultures in which it has been studied. It emerges predictably during ontogeny at roughly 6 months of age, coinciding with the time when infants begin crawling away from their mothers and potentially encountering strangers. And its focus centers on strange males rather than strange females because strange males historically have been more hazardous to infants’ health. Stranger anxiety shows all the characteristics of “improbable design” for achieving a specific function.
* THE THEORY OF evolution by natural selection has revolutionary implications for understanding the design of the human mind and brain, as Darwin himself was the first to recognize (Darwin, 1859). Indeed, a principled understanding of the network of causation that built the functional architecture of the human species offers the possibility of transforming the study of humanity into a natural science capable of precision and rapid progress. Yet, nearly a century and a half after The Origin of Species was published, the psychological, social, and behavioral sciences remain largely untouched by these implications, and many of these disciplines continue to be founded on assumptions evolutionarily informed researchers know to be false…
* Adaptationism is based on the recognition that selection is the only known natural physical process that builds highly ordered functional organization (adaptations) into the designs of species, in a world otherwise continuously assaulted by the ubiquitous entropic tendency of physical systems to become increasingly disordered with time. Thus, although not everything is functional, whenever complex functional organization is found in the architectures of species, its existence and form can be traced back to a previous history of selection. Moreover, for a given selection pressure to drive an allele systematically upward until it is incorporated into the species-typical design, the same selective cause-and-effect relationship must recur across large areas and for many generations. Complex adaptations necessarily reflect the functional demands of the cross-generationally
long-enduring structure of the organism’s ancestral world, rather than modern, local, transient, or individual conditions. This is why evolutionary psychology as an adaptationist field concerns the functional design of mechanisms given a recurrently structured ancestral world, rather than the idea that behavior is the fitness striving of individuals tailored to unique circumstances Consequently, systems of complex, antientropic functional organization (adaptations) in organisms require explanation wherever they are found; their correct
explanation (barring supernatural events or artificial intervention) always involves a specific history of selection in ancestral environments; and so the prediction, discovery, mapping, and understanding of the functional architecture of organisms can be greatly facilitated by analyzing the recurrent structure of a
species’ ancestral world, in conjunction with the selection pressures that operated ancestrally.