William Calvin writes entertainingly about human evolution. But his pet theory that the spark for human intelligence came from throwing proto-javelins at proto-gazelles around water holes is a great example of the unpersuasiveness of evolutionary biology. Throwing requires a high level of fine motor coordination, large motor coordination, and forethought, and greater hunting ability clearly would convey evolutionary advantages. But the explanation is unfalsifiable, and can’t be rationally distinguished from competing theories, like Dunbar’s theory that intelligence arose from gossip, or Terrence Deacon’s theory that intelligence arose from proto-wedding rings (you see, humans need explicit symbols to mark the sexual availability of a female, since we don’t have estrus).
VS Ramachandran, in an overall very good book showing what neuropathology reveals about the working of the brain, includes a throwaway statement that the brain could not have a built-in mechanism for cooking, and cooking must therefore be derivative of other skills.
But one could create a just-so story about cooking that would be as persuasive as the story about throwing. Early humans that learned and remembered how to roast meat and detoxify vegetables would gain more calories and nutrients from their food and have an evolutionary advantage over eaters of raw food. The skills of memory, planning, persistence and communication and cooperation required for cooking would carry over easily to other evolutionary beneficial traits.
Come to think of it, child development casts into question both the throwing theory and the cooking theory. Children learn to talk, walk, stack things, and open things earlier than they can throw or hold pretend tea parties.
The overdetermined storytelling and explanatory traits of humans explain the origin myths generated by evolutionary biology, more than any of the myths explain the origins of human intelligence.
Update: A google search of Ramachandran finds a couple of more recent articles about mirror neurons, a not-yet-proven but more plausible fundamental catalyst for human intelligence. The ability to feel and echo another human’s sensation and action could be fundamental to complex social cooperation and cultural learning. An infant will stick his tongue out in response to his parent’s gesture; babies mirror actions and emotions long before they walk and talk. The mirroring hypothesis seems much more amenable to testing in a variety of ways ranging from genetic distance between humans and other primates, the results of mirroring disability (autism?), and the developmental relationship between mirroring, learning, and social development.