July Fourth is a celebration of outdoor cooking, as well as our nation's birthday. It's time to brush off the barbecue and throw masses of processed meat on the grill.

As we all stand around waiting for the fire to die down so that we can make s'mores, it's also a time to ponder the notion that the barbecue is a ritual 700,000 years old or more, and it might have something to do with our big brains.

Human ancestors started out eating whatever they could; berries, bark, fruit and bits of small animals were probably the main fare. Anthropologists know these early proto-humans had an eclectic, mostly vegetarian, diet 3 million years ago because of the shape and size of their teeth. These folks had small front teeth and with short canines and giant flat molars, a mouth built for grinding, not for ripping apart hunks of flesh.

Around 2.5 million years ago, meat became a big deal.