[2] He is noted for the position that evolutionary processes need to be considered in determining how the mind deals with symbolic information and language.
His central thesis across these works is that the human capacity for symbolic thought arises not from the evolution of a language-specific mental module, but out of evolutionary changes to the prefrontal cortex affecting the executive function of the primate brain.
The enhanced attentional, metacognitive, and retrieval capacities that resulted from these changes made hominids immensely more capable of dealing with social complexity than their ancestors.
When we study literate English-speaking adults living in a technologically advanced society, we are looking at a subtype that is not any more typical of the whole human species, than, say, the members of a hunter-gatherer group.
The truth is, we don't know, but it would profit us greatly to find out, because the human cognitive system, down to the level of its internal modular organization, is affected not only by its genetic inheritance, but also by its own peculiar cultural history.