The Four Forces of Evolution

Chapter 3: Living Primates

Learning Objectives

By the end of this chapter, having fully read it and reviewed the central themes, students should be able to:

1. Understand how humans are part of the primate order.

2. Understand how the differences exhibited in humans and non-human primates are differences of “degree” and not of “kind.”

3. Describe the common physical characteristics of primate species, such as:

a. Sensory organs and the importance of vision

b. Brain size and the cerebral hemisphere

c. Dentition pattern

d. Reproduction

e. Skeletal structure

4. Describe how and why living primates are divided into the five natural groups of:

a. Lemurs and Lorises

b. Tarsiers

c. New World monkeys

d. Old World monkeys

e. Small and Great Apes

5. List the most common characteristics to each of the five primate groups.

6. Discuss how and where primatologists conduct their research.

7. Discuss the ethical considerations that primatologists have to consider when conducting their research.

8. Understand the vast array of behavior and cultural patterns that primates exhibit, such as:

a. Social organization and community behavior

b. Learned behavior

c. Dominance hierarchies

d. Grooming

e. Hunting techniques

f. Sexual practices

g. Raising and protecting the young

h. Various forms of communication

i. Tool use and creation

9. Discuss why numerous primate species are in danger of extinction and why their extinction is important to key anthropological questions about our human heritage.

Detailed Chapter Outline

I. CHALLENGE ISSUE AND STUDENT LEARNING OBJECTIVES

II. METHODS AND ETHICS IN PRIMATOLOGY

A. Much like archaeologists or cultural anthropologists, primatologists employ a variety of methods and techniques to study our closest living relatives

B. Examples of different methods and foci are:

a. Comparative anatomy and physiology

b. Evolutionary relationships

c. Primate behavior in nature and captivity

d. Documenting primate linguistic and conceptual abilities

C. Primatological research also has many ethical dilemmas, such as:

a. How does the presence of researchers affect primate behavior?

b. Does habituating primates to human presence place the primates in danger?

c. Could researchers introduce new diseases into the primate population?

III. PRIMATES AS MAMMALS

A. Humans are classified within the primate order

B. Primates are a subgroup of the class Mammalia

C. Humans and apes (chimpanzees, bonobos, gorillas, orangutans, gibbons, and siamangs) are hominoids -- members of the superfamily Hominoidea

D. As mammals, primate share many characteristics:

a. The young are born live

b. They receive milk from mother’s mammary glands

c. They have a long period of infant and childhood dependency

d. They are highly active and with a relatively constant body temperature

e. They have an efficient respiratory system and a four-chambered heart

f. Their limbs are positioned below their skeletal frame

g. They stop growing when they reach adulthood

h. They have specialized teeth

E. First mammals appeared over 200 million years ago as nocturnal creatures

F. The first primates appeared over 65 million years ago as arboreal creatures

G. Today, most primates are diurnal animals

IV. PRIMATE CHARACTERISTICS

A. Primates share several characteristics and features, despite exhibiting a wide variation as an order

B. The main primate characteristics are the following:

a. Primate teeth

i. Reduction in the number and size of specialized teeth

b. Sensory organs

i. Reduction in the capacity for smell

ii. Finely developed vision

1. Binocular vision

2. Stereoscopic vision

3. Perception of color

iii. Acute sense of touch

1. Fostered by the development of sensitive pads and nails

c. The primate brain

i. An increase in brain size

ii. Elaboration of the cerebral hemisphere

d. The primate skeleton

i. Eyes rotated forward

ii. Specialized skeleton to allow flexible movements and an upright stance

iii. Virtually all primates have an opposable big toe and thumb

iv. Specialized clavicle related to locomotion

v. Retention of a flexible vertebrate limb pattern

V. LIVING PRIMATES

A. There are five groups of contemporary primates

B. Traditionally primates have been divided into prosimians (lemurs, lorises, and tarsiers), monkeys, apes, and humans.

a. Recent molecular evidence suggests tarsiers are closer to monkeys, apes, and humans.

i. Molecular approach divides primates into strepsirhines (lemurs and lorises) and haplorhines (tarsiers, monkeys, apes, and humans)

C. Lemurs and lorises most closely resemble the earliest primates

a. Lemurs are located on Madagascar

i. Lemurs diversified on Madagascar, with many becoming diurnal and terrestrial species

ii. Some ancestral lemurs were very large

b. Lorises are located in Africa and southern and eastern Asia

i. Lorises are all nocturnal and arboreal

ii. Most resemble ancestral primates

c. Lemurs and lorises are small and have retained many mammalian traits like a claw on their second toe known as a “grooming claw”

d. Lemurs and lorises practice grooming with a “dental comb”

D. Tarsiers, in some classification schemes, are grouped with lemurs and lorises as prosimians; however, they are genetically more closely related to apes and monkeys

a. Tarsiers share many attributes with lemurs and lorises

b. They are mainly nocturnal insect eaters

c. They are excellent jumpers and clingers

E. New World monkeys are classified as Anthropoids and located in tropical areas of South and Central America

a. New World monkeys are universally arboreal

b. Some possess prehensile tails

F. Old World monkeys are classified as Anthropoids and located in large areas of Africa and Asia and from Japan to the southern coast of Spain

a. Old World monkey may be arboreal or terrestrial

b. Their tails are not prehensiled

c. Baboons are particularly interesting to paleoanthropologists because they live in environments similar to the environments humans may have emerged in

G. The small and great apes are also classified as Anthropoids and include gibbons, siamangs, bonobos, chimpanzees, orangutans, and gorillas

a. Apes’ primary modes of locomotion are knucklewalking, quadrapedal, and brachiation

b. Apes can walk bipedally, but only for short periods of time

c. Apes are large wide-bodied primates

d. Apes lack a tail

e. There is geographical variation in apes’ locations

i. Gibbons and siamangs are native to Southeast Asia and Malayasia

1. They have short legs and compact, slim bodies

2. Their usual form of locomotion is brachiation

ii. Orangutans are found in Borneo and Sumatra

1. The people of Indonesia gave oranguatans their name “person of the forest.” In the Malay language orang means human and hutan means forest

2. They are more arboreal than the African apes

3. They are primarily solitary and fruit- and insect-eaters

iii. Gorillas are found in tropical Africa

1. They are knuckle-walkers

2. They are vegetarians

3. They are knuckly-walkers

4. They practice “bluffing” in order to defend themselves

iv. Chimpanzees and bonobos are found in tropical Africa

1. They are knuckle-walkers

2. They spend a great deal of time on the ground as foragers

3. They build nests in tress at nights

VI. PRIMATE BEHAVIOR

A. While primates exhibit genetic adaptations to their environments, behavior is also a prime method of primate adaptation

B. Young apes spend more time reaching adulthood than do other mammals

C. Chimpanzee and bonobos behavior and learned cultural patterns are exhibited in:

a. Social organization such as a community

b. Dominance hierarchies

c. Grooming rituals

d. The hunting of other animals

i. Several methods of hunting have been observed in chimpanzees; male hunting parties in the Gombe and highly coordinated team efforts in West Africa

ii. Bonobo females are the primary hunters sharing their meat with other females and less so with other males.

e. Concealed ovulation in bonobos

i. Sexuality goes far beyond male-female mating for the purposes of biological reproduction

ii. Sexual behavior for group cohesion or for the reduction of social tensions

iii. Heterosexual and homosexual practices

f. Prolonged periods of infant dependency

g. Various types of communication

i. Warning calls

ii. Threat calls

iii. Defense calls

iv. Gathering calls

v. Body language and specific gestures

vi. “Pant-hoots”

h. The production of different types of tools. Some examples include:

i. Chimpanzees use leaves as wipes or sponges to get water out of a hollow

ii. Chimpanzees use large sticks are used as clubs. Sticks and stones are used as missiles in aggressive or defensive display

iii. Chimpanzees use twigs as toothpicks on themselves and others

iv. Bonobos have not been observed using tools as extensively as Chimpanzees in the wild

v. Bonobos have been observed using leaves as trail markers in the wild

vi. Captive bonobos have been observed independently making stone tools

VII. THE QUESTION OF CULTURE

A. Culture is not something that is unique to humans

B. Learned and socially generated and shared behavior is vital to non-human primates

C. To understand our heritage and how and why we started to diverge from our primate cousins, it is imperative that we ensure their survival

a. Numerous non-human primates are endanger of becoming extinct due to:

i. The destruction of their habitat by economic development (farming, lumbering, cattle ranching, rubber tapping, burning and clearing of forest)

ii. The fact that they are being hunted for food or sport

iii. Being captured for black-market zoo trades

iv. War

v. The fact that they are captured for biomedical research

vi. Globalization

b. Recent reports show there has been some progress in conservation efforts

VIII. CHAPTER CHECKLIST AND QUESTIONS FOR REFLECTION

Key Terms

Anthropoids

Arboreal

Binocular vision

Brachiation

Community

Diurnal

Dominance hierarchy

Grooming

Haplorhines

Nocturnal

Opposable

Ovulation

Prehensile

Prosimians

Stereoscopic vision

Strepsirhines

Tool