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Human Evolution
and PREHISTORY
PART II: PRIMATE EVOLUTION
AND THE EMERGENCE OF
HOMININES
COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED.
Human Evolution
and PREHISTORY
Chapter Four:
MONKEYS, APES, AND HUMANS:
THE MODERN PRIMATES
Link to the Canadian Association for Physical Anthropology
COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED.
Chapter Preview
What Is The Place Of Humanity Among The
Other Animals?
What Are The Implications Of The Shared
Characteristics Between Humans And The
Other Primates?
Why Do Anthropologists Study The Social
Behaviour Of Monkeys And Apes?
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THE PRIMATE ORDER
Linnaean System
1. Prosimii (“lower primates”)
lemurs, lorises, tarsiers
2. Anthropoidea (“higher primates”)
monkeys, apes, humans
** based on overall similarity of the body plans
within each group
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THE PRIMATE ORDER
** based on genetic relationships (see chapter 3)
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Characteristics of the Primates
 All primates share a number of traits which are
considered to have been shared by a common
ancestor (ancestral traits)
 Some traits are derived, i.e. they have evolved and
changed from those in the common ancestor
 All of these traits are useful to arboreal, or treedwelling, animals
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The Primate Brain
 Enlargement of the brain, particularly cerebral
hemispheres
 Likely due to:
the evolution of visual acuity
insect predation in an arboreal setting
use of the hand as a tactile organ
 Elaboration of the cerebral cortex
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The Primate Sense Organs
Binocular vision
Stereoscopic vision
Decrease in sense of smell
Highly developed sense of touch
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The Primate Dentition
 Basic primate dentition:
incisors, canines, premolars, molars
 Evolutionary changes in:
reduction in number of teeth
function of premolars and molars
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The Primate Skeleton
 Tendency to a high, vaulted
cranium
 Enclosed bony eye socket
 Position of the foramen magnum
(indication of posture)
 Reduced snout or muzzle
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The Primate Skeleton
Great flexibility of the shoulder
(clavicle and (scapula)
Ability to brachiate
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The Primate Skeleton
Pentadactyly
Sensitive pads + nails + opposable
thumb = prehensile grasp
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Reproduction
Female estrus cycle, i.e. the time of
sexual activity during which ovulation
takes place
Small number of offspring at each
birth
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Care of the Young
Longer period of infant dependency
associated with:
An increase in longevity
Longer period of social learning
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Establishing Evolutionary
Relationships
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MODERN PRIMATES
Strepsirhines
Closest to the ancestral
condition
Lemurs (Madagascar)
Lorises (from Africa to
southern and eastern
Asia)
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MODERN PRIMATES
Haplorhines
Tarsiers (Tarsii)
Nocturnal insect eaters
Elongated tarsal (foot bone) for jumping
Arboreal
In vision and nose/lip structure, a resemblance
to monkeys
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MODERN PRIMATES
Haplorhines
Platyrrhini (New World Monkeys), e.g. spider
monkey
Flat noses with widely separated, outwardly flaring
nostrils
Arboreal
Some with prehensile tails
2-1-3-3 dental formula
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MODERN PRIMATES
Haplorhines
Catarrhini (Old World Monkeys)
 Noses with closely spaced, downward pointing
nostrils
 2-1-2-3 dental formula
 Lack of prehensile tails
 Arboreal (e.g. Asiatic langur) or terrestrial (e.g.
baboon)
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MODERN PRIMATES
Haplorhines
Small and Great Apes
 Our closest living relatives
 Semi-erect posture (“top heavy” and “front heavy”)
 Arboreal to varying degrees
 no external tail
 Broad shoulders
 Arms longer than legs (unlike humans)
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MODERN PRIMATES
Haplorhines
Gibbons and Siamangs
Southeast Asia, Malaysia
Extraordinarily long arms
Brachiation (using the arms to move from
branch to branch, with body hanging suspended)
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MODERN PRIMATES
Haplorhines
Orangutans
Borneo and Sumatra
 Move by walking with forelimbs in a fistssideways or a palms-down position
 Alone or in groups of adults, depending on
habitat productivity
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MODERN PRIMATES
Haplorhines
Gorillas
Equatorial Africa
 Focus on field of vision by moving by directing eyes rather
than moving head, like humans
 Ground dwellers, but may sleep in trees
 Knuckle-walkers
 Gentle and tolerant, using bluffing as part of behavioural
repertoire
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MODERN PRIMATES
Haplorhines
Chimpanzees (Pan)
Forested areas of subsaharan Africa
Bonobos (Pan)
Rainforests of Democratic Republic of Congo
 Ground foragers and knuckle-walker
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THE SOCIAL BEHAVIOUR OF
PRIMATES
The Group
In most species females and offspring constitute the
core
Among chimps largest unit is the community, 50+
individuals, although usually in subgroups
Dominance hierarchies exist, both male (e.g. chimps)
and female (e.g. bonobos)
The gorilla group is the “family”, 5-20 individuals
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THE SOCIAL BEHAVIOUR OF
PRIMATES
Individual Interaction
Establish close social bonds with one
another, e.g. bonobo females
Use of grooming, the ritual cleaning
of another animal’s coat
Among bonobos, chimps, gorillas,
the mother-infant bond is strongest
and most long-lasting
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THE SOCIAL BEHAVIOUR OF
PRIMATES
Sexual Behaviour
No fixed breeding season
Sexual activity tends to occur when
the female signals receptivity for
impregnation
Variety of behaviours
Most nonhuman primates are not
monogamous
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THE SOCIAL BEHAVIOUR OF
PRIMATES
Play
Means of learning about the environment
Means of testing strength, e.g. rank in
dominance hierarchies
Means of learning how to behave as adults, e.g.
food-getting activities
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THE SOCIAL BEHAVIOUR OF
PRIMATES
Communication
Vocalization, with a great range of calls,
used together with face and body
movements
Among the great apes calls are mainly
emotional rather than propositional
Visual communication is important
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THE SOCIAL BEHAVIOUR OF
PRIMATES
Home Ranges
Primates move about within circumscribed areas
Range size depends on group size and availability of
food
Gorillas and bonobos will defend, but rarely through
fighting
Chimpanzees react violently in the absence of
sufficient space
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THE SOCIAL BEHAVIOUR OF
PRIMATES
Learning and Toolmaking
 Ability to invent and to pass on knowledge
 Chimpanzees and bonobos make and use tools,
objects used to facilitate some task or activity,
e.g. termite sticks
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THE SOCIAL BEHAVIOUR OF
PRIMATES
Hunting
 Observed among chimpanzees and bonobos,
not gorillas
 For dietary, political, and sociosexual reasons,
e.g. to entice a female in estrus
 Among bonobos, females usually hunt
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ORIGINAL STUDY
The Culture of Chimpanzees
 The latest catalogue of cultural variations for
chimpanzees cites a minimum of 39 examples of
chimpanzee behaviour believed to have a cultural
origin
 Each community of chimpanzees exhibits its own set
of behaviours
 This cultural capacity suggests an underlying shared
ancient ancestry with humans
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THE SOCIAL BEHAVIOUR OF
PRIMATES
 There are many continuities between “us” and
nonhuman primates, although “degree” does make
a difference
 We should not erect “golden barriers” to set us
apart (Stephen Jay Gould)
 We share a common evolutionary heritage
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NEXT TIME:
Macroevolution and the
Early Primates
COPYRIGHT © 2008 Nelson Education Ltd. ALL RIGHTS RESERVED.