The Cognitive Differentiation-Integration Effort Hypothesis: A Synthesis between the Fitness Indicator and Life History Models of Human Intelligence

Abstract

This article presents a potential synthesis between the fitness indicator and life history models of human intelligence through consideration of the phenomena of ability differentiation and integration. The cognitive differentiation-integration effort hypothesis proposes that these effects result from a life history tradeoff between cognitive integration effort, a mating effort component associated with strengthening the positive manifold amongst abilities; and cognitive differentiation effort, a somatic effort component associated with the cultivation of specific abilities. This represents one of two largely independent sources of genetic variance in intelligence; the other is mediated by general fitness and mutation load and is associated with individual differences in levels of 'genetic g'. These two sources (along with a common source of environmental variance) combine to give rise to a variety of cognitive phenotypes characterized by different combinations of high or low levels of 'genetic g' and cognitive specialism or generalism. Fundamental to this model is the assumption that measures of life history speed (K) and g are essentially independent, which is demonstrated via meta-analysis of 10 studies reporting correlations between the variables (ϭ .023, ns, n ϭ 2056). The implications of the model are discussed in an evolutionary, ecological, and developmental context. Seven key predictions are made in the discussion which if tested could provide definitive evidence for the hypothesis.

A review of intelligence GWAS hits: Their relationship to country IQ and the issue of spatial autocorrelation

“…Evolutionary mechanisms such as gene-culture co-evolution (e.g. Feldman & Laland, 1996) are good candidates for the explanation of the apparent high diversifying selection on intelligence (Woodley, 2011). For example, higher "genotypic intelligence" could cause the development of more complex societies, and life in these complex societies might increasingly select for high-IQ genes.…”

The behavioral correlates of overall and distinctive life history strategy.

“…Even more recent variants on this idea are the cognitive differentiation-integration effort (CD-IE) hypothesis (Woodley, 2011;Woodley, Figueredo, Brown, & Ross, 2013) and the strategic differentiation-integration effort (SD-IE) hypothesis (Figueredo, Woodley, Brown, & Ross, in press), which predicts the regulation by life history speed (K) of the magnitudes of the correlations among its components, such that slower life history strategists exhibit less correlated life history traits than faster life history strategists. Thus, slower life history strategists are both cognitively and conatively differentiated with respect to their life history traits because strategic specialization with respect to various domainspecific resource allocations permits resource polymorphism under the conditions of elevated intraspecific social competition characteristic of the higher and more stable population densities of slower life history strategists.…”

The cognitive ecology of Mexico: Climatic and socio-cultural effects on life history strategies and cognitive abilities

“…Woodley (2011) developed a hypothesis to explain the paradox in the relation between life history strategy and general intelligence, the Cognitive Differentiation-Integration Effort Hypothesis, which proposes that the correlation between K and g is attenuated at the individual level due to cognitive specialization at higher levels of K. As slower life history strategists evolve and develop in environments that are more stable, predictable, and controllable, slower life history individuals are able to invest more energetic and biomaterial resources than fast life history strategists to specializing in particular cognitive niches. Thus, as levels of K (slower life history) increase, the positive manifold of correlations between the indicators of intelligence weakens and the strength of the common factor (g) decreases (Woodley, 2011;; these domainspecific indicators thus come to resemble multiple intelligences rather than a unitary general intelligence. The present analysis pursues the socioeconomic implications of those differentiation and integration phenomena for human cognitive abilities.…”