Topic 4: Primate Diet and Nutrition

Milton (1981)

• Digestion is compromise between rate of food passage and nutrient extraction efficiency (inverse relationship)

• Spider and howler monkeys have roughly equivalent gut capacities until colon, howler monkey has colon 2x the length/width of spider monkeys.

• Spider monkeys have shorter colons (less nutrients extracted) but have faster food passage

• Howler monkeys eat more leaves than spider monkeys (who are pretty strictly frugivorous) so makes sense why howlers need more processing time

• Primates cannot just swap diets, morphology does not allow for it to occur

Lambert (1998)

• Ingestion (procurement of food) -> digestion (chemical and mechanical processes) -> absorption -> defecation

• Primate foods consist of lipids, proteins, and carbohydrates

• Carbs are more complex and require specialized morphology to digest. Carb fermentation occurs in stomach and large intestine (distinction between 'foregut' and 'hindgut' fermenters)

• Increased volume of digestive cavity = increased volume of volatile fatty acids

• Larger primates generally have increased capacity to deal with hard-to-digest foods b/c GI tract is physically bigger, BUT…

• Body size does not explain range on dietary adaptation

Lambert & Rothman (2015)

• Fallback foods are not a static or scalable category, nor an intrinsic state of food/consumer

• What a primate has as a ""fallback"" is dependent on the current physiology of a primate

• Fallback foods not rigid (though optimal foraging theory (OFT) treats it as such

• Geometric frameworks (GFs) better at analyzing 'state dependent nutrient needs'

Takahashi et al. (2019)

• Cercopithecus mitis (adult female blue monkeys) are generalists who eat mainly fruits

• Young leaves = fallback foods

• % of fruit in diet and total calories both positively linked to overall fruit availability

• Other variables fluctuate in monkey diets, but their diets maintain overall daily protein & energy intakes

  • Flexibility may contribute to widespread range of C. mitis

  
  

Moy et al. (2023)

• Baboons have similar microbiomes to humans, good model for examining human microbiome

• Baboons on heavily processed diet (aka, human foods) had decrease in microbial alpha diversity and decrease in fiber-degrading bacterial species

• Threshold of dietary alteration must be reached before microbiome is substantially altered