There is recent interest (again) in the evolution of intelligence. Apparently, this is a controversial area of intelligence, with evolutionary accounts regularly proposed, debated, and then mostly ignored until a new proposal comes along. The talk focuses on the possible reasons for this situation and offers solutions
The first reason concerns the issue of variation itself: theories explaining the evolution of intelligence often fail to distinguish between within-individual and between-individual mechanisms, thus confusing universals with variable traits. In theoretical biology variation in an evolutionarily adaptive trait is the exception, not the rule. That is, the explanation of adaptive variation usually requires specific models, since as a general rule evolution works exactly by eliminating variation.
The second reason is the focus on the general factor (g) when providing evolutionary accounts. It is controversial whether g can be meaningfully compared across species. In humans, g is composed of crystallised intelligence (Gc), among other factors: the ability to apply already acquired skills and knowledge, with an emphasis on language – vocabulary, reading comprehension, and verbal reasoning. This does not translate to nonhuman animals, making it unlikely that general factors reflect the same construct across species.
Two solutions are suggested.
First, when providing evolutionary explanations of between-subject constructs (e.g. factors) the focus should be on explaining variation. Relatedly, special emphasis should be laid on traits that demonstrate ergodicity: an overlap between the causes of individual differences and within-individual phenomena.
Second, instead of a reflective approach to g evolutionary accounts should consider a formative approach to the general factor. There are two recent accounts of intelligence that explain the positive manifold without a causal general factor: the Mutualism Model and Process Overlap Theory. According to these accounts g is an emergent, rather than latent property of mental test scores: the common consequence of the covariance among tests rather than its common cause. Such a formative stance could fit well to a comparative approach to intelligence, in which g would vary from species to species (depending on whether its exact composition includes social skills, language, etc.). Under such a formative/functionalist agenda the focus could be on individually identifying the cognitive capabilities of each species, ranging from olfactory abilities to social cognition, and how they uniquely contribute to the given species’ chances of survival and reproduction.
It is also recommended that evolutionary accounts of intelligence should focus on fluid reasoning (Gf). Gf can be meaningfully interpreted as a domain-general ability involved in complex, novel problem-solving. As such, its evolution might have been shaped by pressure to solve novel problems with evolutionary significance. Moreover, it can be interpreted across species, it demonstrates ergodicity, it is central to variation in cognitive abilities, and it is statistically near-indistinguishable from g.
