Chapter 6

A Survey of the Living Primates

Chapter Outline• Primates Characteristics• Primate Adaptations• Geographical Distribution and Habitats• Diet and Teeth

Chapter Outline• Locomotion• Primate Classification• A Survey of the Living Primates• Endangered Primates

Primates As Mammals• There are approximately 190 species of

nonhuman primates• Primates belong to:

Vertebrate class - Mammalia Subgroup of placental mammals.

Prosimians• Members of a suborder of Primates, the

Prosimii. • Traditionally, the suborder includes

lemurs, lorises, and tarsiers.

Primates• Members of the order of mammals

Primates, which includes prosimians, monkeys, apes, and humans.

Anthropoids• Members of a suborder of Primates, the

Anthropoidea.• Traditionally, the suborder includes

monkeys, apes, and humans.

Primates Characteristics• Fur (body hair)• Long gestation followed by live birth• Homeothermy, the ability to maintain a

constant body temperature• Increased brain size• Capacity for learning and behavioral

flexibility.

Primate Limbs • A tendency towards erect posture.• Hands and feet possess grasping ability.• Features of the hands and feet:

5 digits on hand and feet Opposable thumb partially opposable great toe Tactile pads enriched with sensory

nerve fibers at the ends of digits

Primate Limbs• A horse’s front foot,

homologous with a human hand, has undergone reduction from 5 digits to one.

Primate Limbs• Raccoons are capable of

considerable manual dexterity and can readily pick up small objects with one hand, they have no opposable thumb.

Primate Limbs• Many monkeys are able

to grasp objects with an opposable thumb, while others have very reduced thumbs.

Primate Limbs• Humans are capable

of a “precision grip.”

Primate Limbs• Chimpanzees with their

reduced thumbs are capable of a precision grip but frequently use a modified form.

Primate Senses and the Brain• Color vision is a characteristic of all diurnal

primates, nocturnal primates lack color vision.• Depth perception is made possible by eyes

positioned forward on the front of the face.• Decreased reliance on the sense of smell. • The brain has expanded in size and become

increasingly complex.

Binocular Vision in Primates

Primate Maturation• Longer periods of gestation• Reduced numbers of offspring• Delayed maturation• Extension of the entire life span.

Primate Learning and Behavior• Have a greater dependence on flexible,

learned behavior.• Tend to live in social groups. • Males are permanent members of many

primate social groups, a situation unusual among mammals.

Base of an Adolescent Chimpanzee Skull

• In an adult animal, the bones of the skull would be fused together and would not appear as separate elements as shown here.

Question• Which of the following is not a primate

characteristic?a) stereoscopic visionb) highly developed sense of smellc) orthograde or upright postured) prehensility

Answer: b• A highly developed sense of smell is

not a primate characteristic.

Question• Binocular vision in primates contributes

toa) color vision.b) lateral vision.c) panoramic vision.d) stereoscopic vision.

Answer: d• Binocular vision in primates contributes to

stereoscopic vision.

Primate Adaptation• Primate anatomical traits evolved as

adaptations to environmental circumstances. Arboreal Hypothesis Visual Predation Hypothesis Angiosperm Radiation Hypothesis

Arboreal Hypothesis• Arboreal living was the most important

factor in the evolution of primates.• Prehensile hand is adapted to climbing in

the trees.• A variety of foods led to the omnivorous

diet and generalized dentition.

Visual Predation Hypothesis• Primates may have first adapted to

shrubby forest undergrowth and the lowest tiers of the forest canopy.

• Forward facing eyes enabled primates to judge distance when grabbing for insects.

• Flowering plants may have influenced primate evolution.

Angiosperm Radiation Hypothesis• Suggests the basic primate traits were

developed in conjunction with the rise of the angiosperms (flowering plants) that began around 140 mya.

• Flowering plants provide numerous resources for primates, including nectar, seeds, and fruits.

Geographical Distribution of Living Nonhuman Primates

Geographical Distribution of Living Nonhuman Primates

Primate Habitats• Most live in tropical or semitropical areas

of the new and old worlds.• Most are arboreal, living in forest or

woodland habitats.• No nonhuman primate is adapted to a

fully terrestrial environment; all spend some time in the trees.

Primate Diet and Teeth• Generally omnivorous, reflected in their

generalized dentition.• Most eat a combination of fruits, leaves,

and insects.• Most have four types of teeth: incisors,

canines, premolars and molars.

Dental Formula

• The human maxilla (a) illustrates a dental formula characteristic of Old World monkeys, apes, and humans. The Cebus maxilla (b) shows the dental formula typical of most New World monkeys.

Primate Locomotion• Most are quadrupedal, using all four limbs

in their locomotion.• Arm swinging is found among the apes.• Prehensile tails, found only among the

new world monkeys, are used as an aid to locomotion.

Differences in Anatomy and Limb Proportions and Locomotor Patterns

Differences in Anatomy and Limb Proportions and Locomotor Patterns

Differences in Anatomy and Limb Proportions and Locomotor Patterns

Differences in Anatomy and Limb Proportions and Locomotor Patterns

Human Chromosome 2• Human chromosome 2

has banding patterns that correspond to those of chimpanzee chromosomes 12 and 13.

• These similarities suggest that human chromosome 2 resulted from the fusion of these two ape chromosomes during the course of hominid evolution.

Revised Partial Classification of the Primates

• The terms Prosimii and Anthropoidea have been replaced by Strepsirhini and Haplorhini.The tarsier is included in the suborder with monkeys.

Prosimians• The most primitive of the primates.• Characteristics:

Reliance on olfaction Laterally placed eyes Shorter gestation and maturation

periods Dental specialization called the "dental

comb”

Rhinarium• This cat’s rhinarium

enhances his sense of smell.

Dental Comb• Prosimian dental

comb, formed by forward projecting incisors and canines.

Lemurs• Found on the island of Madagascar and other

islands off the coast of Africa.• Extinct elsewhere in the world.• Characteristics:

Larger lemurs are diurnal and eat vegetable foods: fruit, leaves, buds, and bark.

Smaller lemurs are nocturnal and insectivorous (insect -feeding).

Geographical Distribution of Modern Lemurs

Ring Tailed Lemur

Sifakas in Their Native Habitat in Madagascar

Slow Loris

Galago or “Bush Baby”

Lorises• Found in tropical forests and woodlands of

India, Sri Lanka, southeast Asia, and Africa.• Characteristics:

Use a climbing quadrupedalism. Some are insectivorous; others supplement

their diet with fruit, leaves, gums, and slugs. Females frequently form associations for

foraging or in sharing the same sleeping nest.

Tarsiers• Small nocturnal primates found on the

islands of southeast Asia.• Eat insects and small vertebrates which

they catch by leaping from branches.• Basic social pattern appears to be a

family unit consisting of a mated pair and their offspring.

Tarsier

• Geographical distribution of tarsiers.

Question• Which of the following is NOT true of

tarsiers?a)They are nocturnal.b)They are insectivorous.c)They live in groups of 10-12

individuals.d)They can rotate their heads almost

180 degrees.

Answer: c• Tarsiers do not live in groups of 10-12

individuals.

Anthropoids (Monkeys, Apes and Humans)• Common traits:

Larger brain and body size Reduced reliance on the sense of smell Greater degree of color vision Bony plate at the back of the eye socket Different female reproductive anatomy Longer gestation and maturation periods Fused mandible

Monkeys• Represent about 70% of all primate

species.• Divided into two groups separated by

geography and several million years of evolutionary history: New world monkeys Old world monkeys

New World Monkeys• Almost exclusively arboreal.• Found in southern Mexico and central and

south America.• Two families: Callitrichidae and Cebid

New World Monkeys• Prince Bernhard’s titi

monkey (discovered in 2002)

New World Monkeys• Female muriqui with

infant

New World monkeys.• Squirrel monkeys

New World monkeys.• White-faced capuchins

New World monkeys.• Male uakari

New World Monkeys: Callitrichidae • Live in families composed of a mated pair

or a female and two adult males, plus the offspring.

• Males are involved with infant care.

New World Monkeys: Cebid• Possess prehensile tails.• Most live in groups of both sexes and all

ages.• Others live as monogamous pairs with

subadult offspring.

Old World Monkeys• Habitats range from tropical forests to semiarid

desert to snow-covered areas in Japan and china.

• Characteristics: Most quadrupedal and arboreal All belong to the Cercopithecidae family. Divided into subfamilies, the cercopithecines

and the colobines.

Geographical Distribution of Modern Old World Monkeys

Adult Male Sykes Monkey

Savanna Baboons(a) Male (b) Female

Characteristics Distinguishing Hominoids From Monkeys

• Larger body size • Absence of a tail• Shortened trunk• More complex behavior• More complex brain• Increased period of infant development

and dependency

Gibbons and Siamangs• Found in the tropical areas of southeast Asia.• Adaptations for brachiation may be related to

feeding while hanging from branches.• Diet is largely fruit with leaves, flowers, and

insects.• Basic social unit is a monogamous pair and

their offspring. • Males and females delineate their territories

with whoops and “songs”.

Geographical Distribution of Modern Asian Apes

White-handed Gibbon

Orangutans (Pogo pygmaeus)• Found in heavily forested areas of Borneo

and Sumatra.• Almost completely arboreal.• males = 200 lbs, females = 100 lbs• Pronounced sexual dimorphism. • Solitary• Principally frugivorous (feed-eating).

Gorillas (Gorilla Gorilla)• Largest of the living primates.• Confined to forested regions of central Africa.• Males can weigh up to 400 pounds, females

200 pounds.• Primarily terrestrial, using a posture called

“knuckle –walking”.• Groups consist of one large silverback male, a

few adult females, and their subadult offspring.

Geographical Distribution of Modern African Apes

Western Lowland Gorillas(a) Male (b) Female

Mountain Gorillas(a) Male (b) Female

Chimpanzees (Pan Troglodytes)• Found in equatorial Africa.• Anatomically similar to gorillas particularly in

limb proportions and upper-body shape.• Locomotion includes knuckle-walking on the

ground and brachiation in the trees.• Eat a variety of plant and animal foods. • Large communities of as many as 50

individuals.

Chimpanzees(a) Male (b) Female

Bonobos (Pan paniscus) • Only found in an area south of the Zaire river.• Population is believed to only number a few

thousand individuals.• Exploit the same foods as chimps, including

occasional small mammals.• Male-female bonds constitute the societal core.• Sexuality includes frequent copulations

throughout the female's estrous cycle.

Female Bonobos With Young

Humans (Homo Sapiens)• The only living species in the family

Hominidae.• Human teeth are typical primate teeth.• Dependence on vision for orientation to

the world

Humans (Homo Sapiens)• Flexible limbs and grasping hands• Omnivorous diet• Cognitive abilities are the result of

dramatic increases in brain size.• Bipedal

Endangered Primates• Over half of all living primates are

endangered, many face immediate extinction.

• Three reasons: Habitat destruction Hunting for food Live capture for export or local trade

Hunting of Primates• In West Africa the most serious problem

is hunting to feed the growing human population.

• Estimated that thousands of primates, are killed and sold for meat every year.

• Primates are also killed for commercial products.

Question• Which of the following is not a reason that

nonhuman primates are endangered?a) habitat destructionb) hunting for foodc) live capture for either the exotic pet

trade or biomedical researchd) establishment of biological reserves

Answer: d • The establishment of biological

reserves is not a reason that nonhuman primates are endangered.

Tropical Rain Forests of the World