Meat and Evolution

Many commentators try to appeal to an idea of what is natural or healthy, what humans are 'designed' to eat.  For example Gary Smith of the "Center for Red Meat Safety" claims that "Evolutionsist tell us humanity ... should now consider returning to a diet more like that of out Paleolithic ancestors--high-protein and low fat". 

A more dispassionate reading of the evolutionary data suggests that our more distant ancestors were herbivores.  Humans developed into omnivores during the late Miocene era, to provide energy for their relatively large bodies and energetic lifestyles.  As such, humans are naturally omnivores (Deneen, 2002; Milton, 1999; Smil, 2002).

As omnivores humans have some characteristics typical of of our distant herbivore ancestors such as:

• Needing to get our vitamin C from our diet
• Having a intestine that is long in comparison to our body size

However out bodies have been retrofitted in the more immediate evolutionary past to digest meat as is apparent from features such as:

• Production of hydrochloric acid by the stomach

Did Meat Make Us What We Are Today?
It is sometimes argued that switching to an omnivorous diet led directing to an increase in brain size and the evolution of humans as we are today. Others argue that the increased brain and decreased tooth size of hominids developed primarily before the shift to meat-eating and later adaption might related to the handling and cooking of tubers as much as meat (Pasquet and Hladick, 2005).

Conclusion
While consumption of meat is clearly part of our current biological design, it cannot be assumed that because something is natural that it is necessary or good.  People with access to diverse food sources can get all of their nutritional needs from non-animal sources (Smith, 2005).

See also:

•  Why Do People Eat Meat?

References:

• Deneen, S. (2002). Body of evidence: were humans meant to eat meat? E, 13, 33-34.
• Milton K. (1999). A hypothesis to explain the role of meat-eating in human evolution. Evolutionary Anthropology, 11-21.
• Pasquet P, Hladick C-M. (2005). Theories of human evolutionary trends in meat eating and studies of primate intestinal tracts. Estudios Del Hombre, 21-31.
• Smil, V. (2002). Eating meat: evolution, patterns and consequences. Population and Development Review, 28, 599-639.
• Smith GC. (2005). Why people eat beef. National Cattlemen's Beef Association Annual Convention in San Antonio, TX. February 2, 2005.