The American Dietetic Association notes that "most of mankind for most of human history has lived on vegetarian or near-vegetarian diets."

Meat-eaters: have claws

Herbivores: no claws

Humans: no claws

Meat-eaters: have no skin pores and perspire through the tongue

Herbivores: perspire through skin pores

Humans: perspire through skin pores

Meat-eaters: have sharp front teeth for tearing, with no flat molar teeth for grinding

Herbivores: no sharp front teeth, but flat rear molars for grinding

Humans: no sharp front teeth, but flat rear molars for grinding

Meat-eaters: have intestinal tract that is only 3 times their body length so that rapidly decaying meat can pass through quickly

Herbivores: have intestinal tract 10-12 times their body length.

Humans: have intestinal tract 10-12 times their body length.

Meat-eaters: have strong hydrochloric acid in stomach to digest meat

Herbivores: have stomach acid that is 20 times weaker than that of a meat-eater

Humans: have stomach acid that is 20 times weaker than that of a meat-eater

Meat-eaters: salivary glands in mouth not needed to pre-digest grains and fruits.

Herbivores: well-developed salivary glands which are necessary to pre-digest grains and fruits

Humans: well-developed salivary glands, which are necessary to pre-digest, grains and fruits

Meat-eaters: have acid saliva with no enzyme ptyalin to pre-digest grains

Herbivores: have alkaline saliva with ptyalin to pre-digest grains

Humans: have alkaline saliva with ptyalin to pre-digest grains

Based on a chart by A.D. Andrews, Fit Food for Men, (Chicago: American Hygiene Society, 1970)

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