Table: The Comparative Anatomy of Eating

Comparative Anatomy of Eating (Dr. Milton Mills)
Trait	Human	Herbivore	Omnivore	Carnivore
Intestines: Small	10–11 times body length	10–12+ times body length	4–6 times body length	3–6 times body length
Intestines: Colon	Long, sacculated	Long, complex; may be sacculate	Simple, short, and smooth	Simple, short, and smooth
Teeth: Incisors	Broad, flat, and spade shaped	Broad, flat, and spade shaped	Short and pointed	Short and pointed
Teeth: Canines	Short and blunted	Dull and short or long (for defense) or none	Long, sharp, and curved	Long, sharp, and curved
Teeth: Molars	Flat with nodular cusps	Flat with cusps vs. complex surface	Sharp blades or flattened	Sharp, jagged, and blade shaped
Saliva	Carbohydrate-digesting enzymes	Carbohydrate-digesting enzymes	No digestive enzymes	No digestive enzymes
Stomach: Type	Simple	Simple or with multiple chambers	Simple	Simple
Stomach: Acidity with Food	pH 4–5	pH 4–5	≤ pH 1	≤ pH 1
Stomach: Capacity	21% to 27% of total volume of digestive tract	< 30% of total volume of digestive tract	60% to 70% of total volume of digestive tract	60% to 70% of total volume of digestive tract
Chewing	Extensive chewing necessary	Extensive chewing necessary	Swallows food whole or simple crushing	None; swallows food whole
Nails	Flat nails	Flat nails or blunt hooves	Sharp claws	Sharp claws
Jaw: Type	Expanded angle	Expanded angle	Angle not expanded	Angle not expanded
Jaw: Joint Location	Above the plane of the molars	Above the plane of the molars	On the same plane as molar teeth	On the same plane as molar teeth
Jaw: Motion	No shearing; good side-to-side, front-to-back motion	No shearing; good side-to-side, front-to-back motion	Shearing; minimal side-to-side motion	Shearing; minimal side-to-side motion
Major Muscles	Masseter and pterygoids	Masseter and pterygoids	Temporalis	Temporalis
Mouth Opening vs. Head Size	Small	Small	Large	Large
Facial Muscles	Well developed	Well developed	Reduced	Reduced to allow wide mouth gape
Liver	Cannot detoxify vitamin A	Cannot detoxify vitamin A	Can detoxify vitamin A	Can detoxify vitamin A
Kidney	Moderately concentrated urine	Moderately concentrated urine	Extremely concentrated urine	Extremely concentrated urine
	Source: Mills, M.D., Milton. “The Comparative Anatomy of Eating | Digestion | Gastrointestinal Tract.” Scribd. Accessed February 15, 2019. https://www.scribd.com/doc/94656/The-Comparative-Anatomy-of-Eating.