(p. 211) Development
Over the preceding sections, a theme has been developing which now comes into sharp focus: namely, that understanding the evolved psychology of ourselves and other animals requires a much better understanding of the process of ontogeny and the selective pressures that have acted on it. Issues of developmental robustness raised by Mameli, ecological inheritance as discussed by Laland, and the notion that the phylogenetic origins of culture are to be found in ontogenetic processes (put forward by van Schaik and Silk) all receive elaboration here, in the context of explaining various aspects of normal human development.
For humans, in particular, an understanding of ontogenetic processes is crucial given the cultural niche we occupy: it means that we live in worlds almost entirely of our own construction, both literally and imaginatively. The means by which children come to appreciate the nature of their world has been canalized over the course of our evolution, enabling them to attend to the social information that is crucial for normal functioning almost from the moment they enter the world, as Baron-Cohen argues, and which can lead to the disabilities of autism when such mechanisms fail.
However, it is also clear that, despite this canalization, evolution has provided us with mechanisms that are highly ‘experience-expectant’ and require input from the world in order to refine the categories of stimuli to which they respond. Wyman and Tomasello argue that, if these early social mechanisms are in place, in particular the ability to engage in joint attention, the rest then follows in a cascade, as knowledge gained at one stage bootstraps the development of subsequent stages: a combination of classic Piagetian and Vygotskian approaches, but with the added evolutionary suggestion that the ability to enter into cooperative, collaborative interactions from the earliest stages of life is what differentiates us from the other apes.
The peculiar life history of humans (see Section V), and the long developmental periods we experience relative to other species, also provides a rich source of ideas concerning the links between phylogeny and ontogeny. While more research is still needed, it is becoming clear that, as Belsky argues, childhood experiences have a strong influence on the reproductive strategy an individual is likely to adopt as an adult, and that such choices are often highly adaptive in a given environment. Family environments, in particular, seem to play a strong, yet synergistic, role in shaping individual development, as both Sulloway and Bereczkei suggest using various examples to illustrate the ‘evocative’ nature of development.
The proximate mechanisms that underlie the life trajectories and reproductive strategies followed, and which allow individuals to respond flexibly to prevailing circumstances, often have deep physiological roots, as both Bereczkei and Flinn argue. Flinn, in particular, echoes the arguments put forward by Panksepp (Chapter 12), that hormonal/neurochemical responses are crucial for understanding neurological and psychological development, both evolutionarily and over the course of individual lifespans. Bereczkei also illustrates how sociality and social contact itself are crucial for the development of healthy, normally functioning individuals, while, at the same time, the mechanisms that rely on these social inputs are fairly robust; human children can (p. 212) show remarkable resilience in the face of social and other stressors. This is what we should expect from evolution—mechanisms that are heavily dependent on highly specified inputs would be at a disadvantage in competition with more broadly constrained mechanisms. A loving family seems to be the key to normal human development, but its precise composition, and the manner in which individuals engage with children and other family members, can be much more variable and fluid. Indeed, this variability can be crucial for the acquisition of culturally specific behaviours that allow individuals to become fully functioning, independent members of society.