Humans Are Biologically Herbivorous [人类天生就是草食性生物]

Humans Are Biologically Herbivorous [人类天生就是草食性生物]
	Carnivores  [食肉动物]	Omnivores [杂食动物]	Herbivores  [食草动物]	Humans  [人类]
Facial muscles	Reduced to allow wide mouth gape	Reduced	Well-developed	Well-developed
Jaw type	Angle not expanded	Angle not expanded	Expanded angle	Expanded angle
Jaw joint location	On same plane as molar teeth	On same plane as molar teeth	Above the plane of the molars	Above the plane of the molars
Jaw motion	Shearing; minimal side-to-side motion	Shearing; minimal side-to-side motion	No shear; good side-to-side, front-to-back	No shear; good side-to-side, front-to-back
Major jaw muscles	Temporalis	Temporalis	Masseter and ptergoids	Masseter and pterygoids
Mouth opening vs. head size	Large	Large	Small	Small
Teeth: Incisors	Short and pointed	Short and pointed	Broad, flattened and spade-shaped	Broad, flattened and spade-shaped
Teeth: Canines	Long, sharp, and curved	Long, sharp and curved	Dull and short or long (for defense), or none	Short and blunted
Teeth: Molars	Sharp, jagged and blade-shaped	Sharp blades and/or flattened	Flattened with cusps vs. complex surface	Flattened with nodular cusps
Chewing	None; swallows food whole	Swallows food whole and/or simple crushing	Extensive chewing necessary	Extensive chewing necessary
Saliva	No digestive enzymes	No digestive enzymes	Carbohydrate digesting enzymes	Carbohydrate digesting enzymes
Stomach type	Simple	Simple	Simple or multiple chambers	Simple
Stomach acidity  with food in stomach	≤ pH 1	≤ pH 1	pH 4-5	pH 4-5
Length of small intestine	3-6 times body length	4-6 times body length	10-12+ times body length	10-11 times body length*
Colon	Simple, short, and smooth	Simple, short, and smooth	Long, complex; may be sacculated	Long, sacculated
Liver	Can detoxify vitamin A	Can detoxify vitamin A	Cannot detoxify vitamin A	Cannot detoxify vitamin A
Kidney	Extremely concentrated urine	Extremely concentrated urine	Moderately concentrated urine	Moderately concentrated urine
Nails	Sharp claws	Sharp claws	Flattened nails or blunt hooves	Flattened nails
Taken from The Comparative Anatomy of Eating, by Milton R. Mills, M.D.  * "Body length" measured from neck to anus, as with the other animals.

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