An alternative theoretical approach to the study of historical influences on psychological aging with particular application to cognition has been presented by Willis and Schaie (2006 ; see also Schaie, a ). Both neurobiological and sociocultural influences on development have long been recognized. Co-evolutionary theorists ( Boyd & Richerson, 1985; Cavalli-Sforza & Feldman, 1981; Dunham, 1991; Tomasello, 1999 ) maintain that both biological and cultural evolution has occurred and that recent, cohort-related advances inhuman development in domains such as intelligence can be attributed largely to cumulative cultural evolution. Cultural activities impact the environment influencing mechanisms such as selection processes thus allowing humans to co-direct their own evolution ( Cavalli-Sforza & Feldman, 1981; Dunham, 1991 ). Baltes ’ co-constructionist approach imposes a lifespan developmental perspective on co-evolutionary theory and provides principles regarding the timing of the varying contributions of neurobiology and culture at different developmental periods and across different domains of functioning perspective proposed by Baltes and colleagues (Baltes, 1997 ; Li, 2003; Li & Freund, 2005 ).
Three principles are proposed regarding the relative contributions of biology and culture influences across the lifespan) The beneficial effects of the evolutionary selection process occur primarily in early life and are less likely to optimize development in the latter half of life. (2) Further advances inhuman development depend on ever increasing cultural resources. From a historical perspective, increases in cultural resources have occurred via cumulative cultural evolution and have resulted in humans reaching higher levels of functioning. At the individual level, increasing cultural resources are required at older ages for further development to occur or to prevent age-related losses. (3) In old age, the efficacy of increasing cultural resources is diminished due to decline in neurobiological functions.
Ina related co-evolutionary approach, Tomasello and others ( Dawkins, 1989; Dunham, 1991; Tomasello, 1999 ) have proposed mechanisms for social transmission of cultural knowledge. Humans have evolved forms of social cognition unique to humans, which have enabled them not only to create new knowledge and skills but more important to preserve and socially transmit these cultural resources to the next cohort/generation. Cultural learning thus involves both social transmission of cultural knowledge and resources developed by one person, and also sociogenesis or collaborative learning and knowledge creation.