The claim was that "cancer was all but unknown" in hunter-gatherer eras, and only dramatically increased in tandem with modern diets.

Since wild animals appear to get cancer as often as humans, this seems unlikely:-

http://www.livescience.com/9680-cancer-kills-wild-animals.html

As far as Gary Taubes is concerned, my own experience was that cooked animal foods made me extremely fat, while cooked or raw carb-heavy vegan diets made me ultra-thin( and eternally, ravenously hungry etc., but anyway..).

Geoff