What primates need
 

All primates need protein, carbohydrates, fats, vitamins and minerals, and water.

Primate foods: where they get what they need
 

Primates eat leaves, fruits, seeds, prey, gum, corms, flowers and nectar. 

What sorts of nutrients do each of these dietary items provide?

Some primates also eat soil occasionally, but it is controversial as to why they do this.

Primates generally eat at least one class of items high in protein (e.g. leaves, animal prey) and at least one class of item high in carbohydrates (e.g. fruit, insects, gum).

What body part of insects is particularly rich in carbohydrates?

Primate species are generally assigned to one of three general dietary categories: frugivores, folivores, or insectivores. 

 
How and why foods differ in abundance

Why are plant foods more abundant than animal foods? 

Why do potential plant foods appear to be more abundant than they really are?

How do secondary compounds in plant material act as feeding deterrents?  Be sure you understand the differences between alkaloids and tannins.

How have some animals overcome the deterrent effects of certain alkaloids?

Why are fruits less abundant than leaves? 

Why are young leaves less abundant than mature leaves?

Factors that influence variation in primate diets
 

1) Body Size and Basal Metabolic Rate (BMR)

The amount of energy needed is closely related to body size. The larger the body, the more total energy needed.

BMR is the rate at which energy is used up or exchanged in basic life processes.   It is measured in terms of O₂ depletion per unit time.

BMR relationship to body weight

Kleiber's Law:  Mathematical expression of the relationship of BMR to weight: BMR=kW^.75, where k= constant and W=weight

From the figure above, larger animals use less energy per unit body weight even though larger animals have a higher BMR than smaller animals. 

The larger the animal, the more efficient it is at utilizing energy from a source.  This is graphically represented by plotting the Mass-Specific Basal Metabolic Rate (MSMR=BMR/weight) versus body weight.

MSMR relationship to body weight

 
 
 

Primates less than 600 g generally concentrate on insects, while primates larger than 600 g generally concentrate more on leaves to obtain protein.   This relationship between body size and choice of food is summarized in the Jarman Bell Principle. 

Jarman Bell Principle: 
 
 

	total nutrient requirements	nutrient requirement per body weight
large animal	large amount (abundant food)	small amount (poor quality food)
small animal	small amount (rare food)	large amount (high quality food)

Why are nearly all large primates unable to subsist primarily on insects? 

2) Activity level

By being relatively inactive, a primate can reduce the amount of energy it needs (e.g. sportive lemurs, colobus monkeys)

3) Physiological demands of growth and reproduction

Females tend to focus on foods that are higher in energy and protein.

4) Adaptations and behavioral specializations for harvesting food

a) Anatomical: What are the anatomical specializations of aye ayes, marmosets, brown capuchins, and baboons that allow them to exploit foods unavailable to other primates? 

b) Behavioral specializations: special skills, cecotrophy, tools, cooperation 

5) Adaptations for processing and digesting foods

a) Dental specialization (tooth structure varies with diet) 

b) Sacculated stomach (e.g. colobine monkeys) 

c) Enlarged hindgut (e.g. howler monkeys) 

6) What is available in the local habitat

Food availability varies between locations. 

At a single location, why might capuchin monkey diet vary from season to season and from year to year? 

Pages 167-180: How Humans Evolved

These pages cover primate diets and activity patterns. 

You can review the concept of basal metabolic rate by consulting pages 167-168. 

Minerals, nutrients, secondary compounds and food items in the diets of primates are reviewed on pages 168-173.

Why is foraging in a tropical forest not an easy task for primates?

Primate dietary adaptations of the teeth and gut are discussed on page 175.  Why do folivores tend to have more specialized digestive systems than frugivores and insectivores?

Why do primatologists believe that primates evolved from a nocturnal ancestor?

The proportion of time spent on different activities (e.g. feeding, moving, resting) is influenced to some extent by ecological conditions (e.g. food abundance and dispersion).

Pages 133-137: The Primate Anthology

What are some of the problems posed by a leafy diet and how have some primates solved these problems?

Why do folivores generally have smaller home ranges and shorter daily path lengths than frugivores?

Chapter 14: The Primate Anthology

How did meat-eating behavior develop and spread among young baboons at Kekopey?

In what ways do the authors think a change in "food supply" promoted baboon hunting behavior at Kekopey?

Chapter 21: The Primate Anthology

Note that the howler monkey diet at Canas differs seasonally.

What was the relationship between alkaloids and food choice at Canas?

Why is it overly simplistic to assume that folivores like the howlers at Canas have access to an ubiquitous food source (i.e. leaves)?

Chapter 23: The Primate Anthology

Uakaris are among the most frugivorous of the primates.  How do they manage to subsist on seeds even when fruits are at their rarest?

Why does the author believe uakaris fail to inhabit the nearby dry forests where so many other primate species thrive?

Chapter 24: The Primate Anthology

What food item do marmosets at Fazenda Montes Claros specialize on?

What morphological adaptations do marmosets possess that facilitate their specialization on this food item?

Why do marmoset food preferences vary based on the time of year? 

Chapter 26: The Primate Anthology

If muriquis prefer fruit to leaves, why is their diet composed more of leaves than fruit?

Why must howler monkeys be more choosy about the leaves they eat than muriquis?

What is the evidence that the diet of muriquis at Fazenda Montes Claros helps them combat parasite infection?