What other animal would plan an event, provide food to unrelated others, and sit together and share it without a food fight, all while laughing about stories of the past and hopes and dreams of the future ? There is none. No matter how smart your family dog may be, he would not divvy up a prime rib roast and pass it out to the other dogs of the neighborhood with a happy little bark; neither would our closest relatives, the chimps. Humans are social beings, and although there are other animal and insect species that are social, our species takes sociability to a previously unknown level. We are party animals, and on our way to becoming such we have evolved a whole host of unique features - features so unique that we humans are playing in another ballpark.
I’m not sure how convincing an argument Gazzaniga makes (I bailed out during his discussion of primate brain biology, including “the intriguing Brodmann Area 10”), but I do find his premise comforting. Next time I find myself overindulging at a wedding reception, I will feel less like a lush and more like a philosopher-king.