I found this item from http://abcnews.go.com/sections/living/ interesting.
Humans have been cooking their food for a long time.


                      By 1.9 million years ago, when Homo erectus
                 appeared, teeth became smaller and jawbones
                 less robust. Females got bigger-closer in size
                 to males. Brains and bodies both grew.
                      Laden and Wrangham said the changes
                 occurred because the pre-humans had
                 discovered fire and learned how to make roots
                 and other vegetables easier to eat and more
                 nutritious.
                      While some anthropologists argue it was
                 because meat entered the diet, L
aden and a
                 team of anthropologists, nutritionists and
                 primatologists argued otherwise.
                      "However you put meat in doesn't fit in," he
                 said.

                 Some Meat Consumed
                      Laden pointed to recent studies that
                 indicated pre-humans ate some meat-probably
                 scavenged from carcasses-more than 2.5
                 million years ago. But their bodies did not
                 change until much later.
                      "At 2 million years we see no change in the
                 distribution of (animal) bones (at pre-human
                 sites) and we don't see meat as being
                 high-energy food source. It has to be (a)
                 high-energy food source to explain this doubling
                 of body size," he said.
                      I
n addition, evidence is building that humans
                 started to use fire just at the time their bodies
                 changed. Meat is just as nutritious whether it is
                 raw or cooked, but plant food is not.
                      "(Cooking) also makes a lot of things less
                 toxic and more chewable. If you are an ape with
                 fire, there is a much longer list of foods you
                 can eat," Laden said.
                      "We strongly suspect hominids began using
                 fire about 1.9 million years ago, when Homo
                 erectus appeared," he added.

                 Fire for Half Million Years
                      He said colleagues working in Kenya have
                 recently contacted his team and said they have
                 evidence that humans were controlling fire that
                 long ago. The most rece
nt accepted evidence
                 puts fire use at just 200,000 to 500,000 years
                 ago.
Cathryn