Wrangham says that it's highly likely our ape-like ancestors stumbled upon ways to prepare food for easy digestibility; it's hard otherwise to explain their evolution into the small-toothed, upstanding, large-brained creatures we became. He says scientists have wrongly assumed that food preparation came along much later in the evolutionary timeline, after more human-like people came to be. As part of his argument he gives evidence that cooking was a much more significant breakthrough than other types of food preparation (such as pounding meat with a stone to tenderize it or drying it for preservation).
Here's Wrangham's brief mention of Kanzi:
Almost all the methods hunter-gatherers use to improve the nutritional value of plant foods involve fire, because heat is needed to gelatinize starch. Until fire was controlled, habilines [an early humanoid species] would have been stuck with eating raw plant foods whose caloric value could not be much improved by cold processing.One of the nice things about this anecdote is its use of a scientific observation in a way that's opposite to the norm. Where Wrangham tells us that our humanoid ancestors must have been at least as bright as the apes with which they associated, the norm has been to show that our evolutionary development hasn't taken us as far from the apes as we've thought. I think the inference we've been expected to draw from the ethnographic studies of recent decades is that humankind has been absurdly arrogant in assuming dominion over the dumb beasts of God's creation because, they say, many of these beasts — chimps and other apes, dolphins, whales, etc. — are hardly dumb.
The breakthrough could have been simple, because it did not require that fire be made from scratch. If fire could be captured, the tending would have been relatively easy. Among hunter-gatherers, children as young as two years old make their own fires by taking sticks from their mothers' fires. Even chimpanzees and bonobos can tend fires well. The bonobo Kanzi is famous for his ability to communicate with psychologist Sue Savage-Rumbaugh using symbols. During an outing in the woods, Kanzi once touched the symbols for "marshmallow" and "fire:' He was given matches and marshmallows, and he proceeded to snap twigs for a fire, light them with matches, and toast the marshmallows. By the time of habilines, brain size had roughly doubled compared with the relative brain size of great apes. It is very likely that habilines were mentally capable of keeping a fire alive.
-- p. 190, emphasis added
Wrangham reminds us that this romantic view of fellow creatures can easily be taken too far.
His corrective brings to mind the many TV chimps of my youth. Cute, human-like chimps were a staple in popular entertainment beginning with these TV shows of the 1950s. There was, for example, J. Fred Muggs on the Today Show, beginning in 1953 and many more to follow. I think the fad began with the appearance of Cheeta in the Tarzan movies of the 1930s and '40s (who's been in the news lately).
I suppose, since I've shown so much of Cheeta (and O'Sullivan's legs), I should include Bonzo as well:
Here are some Kanzi links:
A TED talk by Kanzi's trainer:
Susan Savage-Rumbaugh on apes
A lecture by Prof. Jeffrey Elman at UCSD:
Speaking Bonobo in Smithsonian mag
Kanzi: Conversation with an Ape in Cricket mag
Speaking Bonobo - The Language of 'Kanzi' on a blog