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I guess the obvious question in all this is, if animal proteins above a certain threshold cause cancer (broadly stated), then what about carnivores? What is dif

I guess the obvious question in all this is, if animal proteins above a certain threshold cause cancer (broadly stated), then what about carnivores? What is different about their metabolism that lets them survive on a diet of pure animal flesh? As omnivores, do we share any of these processes, or are we really just herbivores that have become omnivores through cooking? Do you know of any research in this area?

grandalf 17y ago
I'm not familiar with specific research, but consider the following logical argument based on evolutionary theory: Any species has some set of foods it is capable of digesting. The set of such foods is a function of the environment in which the species has evolved. All of these specializations/tradeoffs of an organism's design (fangs, intestinal tract length, stomach composition, etc.) are a function of the species' unique evolutionary environmental history, and should be viewed as optimizations over past environmental factors. There is also the important factor of calorie scarcity as a driver of selection -- through most of evolutionary time, simply getting enough calories was paramount for all species, including the human species. Also note that there is significantly greater selection pressure for characteristics that facilitate survival through reproductive age even at the expense of overall longevity... so being able to eat (or even craving) a food that causes disease at age 60 historically offered a benefit well through the reproductive age and thus offered a net selection advantage. So, if one takes the list of foods a species is capable of eating and removes the notion of calorie scarcity, one can determine which foods are most optimal for vitality and longevity... Most of the arguments for why humans should eat meat, fats, etc., are based on the implicit assumption of calorie/nutrient scarcity. Of course if you're stranded in the arctic it's a great idea to eat some seal blubber... and it makes sense from an evolutionary perspective to crave it or to enjoy the smell of cooking meat. But when you're living in an advanced, rich society with essentially no calorie/nutrient scarcity, it becomes possible (and fun) to address the question of optimal nutrition.

grandalf 17y ago

I'm not familiar with specific research, but consider the following logical argument based on evolutionary theory: Any species has some set of foods it is capable of digesting. The set of such foods is a function of the environment in which the species has evolved. All of these specializations/tradeoffs of an organism's design (fangs, intestinal tract length, stomach composition, etc.) are a function of the species' unique evolutionary environmental history, and should be viewed as optimizations over past environmental factors. There is also the important factor of calorie scarcity as a driver of selection -- through most of evolutionary time, simply getting enough calories was paramount for all species, including the human species. Also note that there is significantly greater selection pressure for characteristics that facilitate survival through reproductive age even at the expense of overall longevity... so being able to eat (or even craving) a food that causes disease at age 60 historically offered a benefit well through the reproductive age and thus offered a net selection advantage. So, if one takes the list of foods a species is capable of eating and removes the notion of calorie scarcity, one can determine which foods are most optimal for vitality and longevity... Most of the arguments for why humans should eat meat, fats, etc., are based on the implicit assumption of calorie/nutrient scarcity. Of course if you're stranded in the arctic it's a great idea to eat some seal blubber... and it makes sense from an evolutionary perspective to crave it or to enjoy the smell of cooking meat. But when you're living in an advanced, rich society with essentially no calorie/nutrient scarcity, it becomes possible (and fun) to address the question of optimal nutrition.