Eldra Solomon
Linda Berg
Diana W. Martin
www.cengage.com/biology/solomon
Chapter 22
(Sections 22.1-22.4)
The Evolution of Primates
Albia Dugger • Miami Dade College
Drs. Mary and Louis Leakey Study
Fossil Teeth from Australopithecus
Fig. 22-CO, p. 465
Paleoanthropology
• Fossil evidence from paleoanthropology, the study of human
evolution, allows scientists to infer the structure and habits of
early humans and other primates
• Teeth, which have changed dramatically during the course of
primate and human evolution – can identify an individual’s
species, approximate age, diet, and sex
Origins of Primates
• Based on fossil evidence, paleontologists hypothesized that
the first primates descended from small, shrewlike placental
mammals that lived in trees and ate insects
• Many traits of the 233 living primate species are related to
their arboreal (tree-dwelling) past
22.1 PRIMATE ADAPTATIONS
LEARNING OBJECTIVE:
• Describe the structural adaptations that primates have for
life in treetops
Primates
• Primates includes lemurs, tarsiers, monkeys, apes, and
humans
• The first primates appeared by the Early Eocene (56 mya)
• Several novel adaptations evolved in early primates that
allowed them to live in trees
Primate Characteristics
• Five highly flexible digits, including an opposable thumb (or
big toe) used to grasp objects with precision
• Stereoscopic vision: Eyes in the front of the head allow
integration of visual information from both eyes together –
important in judging distance and depth perception
• Relatively large brain, associated with increased sensory
input, intelligence, and socialization
KEY POINT: Primate Hands and Feet
Hand
Foot
(a) Lemur (Eulemur mongoz)
Fig. 22-1a, p. 466
Hand
(b) Tarsier (Tarsius spectrum)
Foot
Fig. 22-1b, p. 466
Hand
Foot
(c) Woolly spider monkey (Brachyteles
arachnoides)
Fig. 22-1c, p. 466
Hand
Foot
(d) Gorilla (Gorilla gorilla)
Fig. 22-1d, p. 466
KEY CONCEPTS 22.1
• Humans are classified in the order Primates, along with
lemurs, tarsiers, monkeys, and apes
• This classification is based on close evolutionary ties
22.2 PRIMATE CLASSIFICATION
LEARNING OBJECTIVES:
• List the three suborders of primates and give
representative examples of each
• Distinguish among anthropoids, hominoids, and
hominins
Classification
• Order Primates
• Suborder Prosimii (lemurs, galagos, and lorises)
• Suborder Tarsiiformes (tarsiers)
• Suborder Anthropoidea or anthropoids (monkeys, apes,
and humans)
Tarsiers
• Nocturnal primates
found in rain forests
of Indonesia and the
Philippines
Fig. 22-3, p. 468
Suborder Anthropoidea
• Anthropoid primates arose in Africa or Asia during the Middle
Eocene epoch (45 mya)
• The oldest anthropoid fossils (Eosimias), found in China and
Myanmar, were small, insect-eating arboreal primates that
were active during the day
• One significant difference between anthropoids and other
primates is the size of their brains
New World and Old World Monkeys
• New World monkeys (in South and Central America)
• Arboreal; some have prehensile tails
• Include marmosets, capuchins, howler monkeys, squirrel
monkeys, and spider monkeys
• Old World monkeys (in Africa, Asia, and Europe)
• Some are arboreal; none have prehensile tails
• Ground dwellers are quadrupedal
• Include baboons, macaques, guenons, mangabeys,
langurs, and colobus monkeys
New World and Old World Monkeys
(a) New World monkey. The white-faced
monkey (Cebus capucinus) has a
prehensile tail and a flattened nose with
nostrils directed to the side.
Fig. 22-4a, p. 468
(b) Old World monkey. The Anubis baboon
(Papio anubis) is native to Africa. Note that
its nostrils are directed downward.
Fig. 22-4b, p. 468
Hominoids
• hominoids
• A group composed of apes and hominins (humans and
their ancestors; also called hominids)
• A cat-sized, forest-dwelling arboreal monkey with a few
apelike characteristics, Aegyptopithecus, lived during the
Oligocene epoch (34 mya)
• Apes and Old World monkeys diverged 25 mya to 23 mya
Hominoids (cont.)
• The oldest fossils with hominoid features (Proconsul)
appeared about 20 mya
• Dryopithecines (Dryopithecus, Kenyapithecus,
Morotopithecus), apes that lived about 15 mya, may have
given rise to modern apes as well as to humans
• Five genera of hominoids exist today: gibbons (Hylobates),
orangutans (Pongo), gorillas (Gorilla), chimpanzees (Pan),
and humans (Homo)
Primate Evolution
Suborder Anthropoidea (Anthropoids)
Hominoids
Lesser Apes
Great Apes
Suborder Prosimii
Suborder Tarsiiformes
Lemurs
Tarsiers
New World Old World
monkeys monkeys
Gorillas
Gibbons Orangutans
Chimpanzees Humans
Common
anthropoid
ancestor
Common
hominoid
ancestor
Common
primate
ancestor
Fig. 22-2, p. 467
ANIMATION: Primate evolutionary tree
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Ape Evolution
(a) Fossils of Aegyptopithecus, a fairly primitive anthropoid, were
discovered in Egypt.
Fig. 22-5a, p. 469
(b) Skeletal reconstruction of Proconsul. (The reconstructed
parts are white.) This anthropoid had the limbs and body
proportions of a monkey but lacked a tail, like all apes.
Fig. 22-5b, p. 469
(c) Dryopithecus, a more advanced ape, may have been
ancestral to modern hominoids.
Fig. 22-5c, p. 469
Ape Locomotion
• Gibbons and orangutans are tree dwellers (can brachiate)
• Chimpanzees and gorillas have adapted to life on the
ground; they use their long arms to assist in quadrupedal
walking (knuckle walking)
• Like humans, apes lack tails, which makes them easy to
distinguish from monkeys
Apes
(a) A mother whitehanded gibbon
(Hylobates lar)
nurses her baby.
Gibbons are
extremely acrobatic
and often move
through the trees
by brachiation.
Fig. 22-6a, p. 470
(b) An orangutan
(Pongo pygmaeus)
mother and baby.
Orangutan anatomy
is adapted to living
in trees.
Fig. 22-6b, p. 470
(c) A young
lowland gorilla
(Gorilla gorilla) in
knuckle-walking
stance. Gorillas
spend most of the
day eating plants.
Fig. 22-6c, p. 470
(d) A mother bonobo
chimpanzee (Pan
paniscus) holds her
sleeping baby.
Bonobos are
endemic to a single
country, the
Democratic
Republic of Congo.
Fig. 22-6d, p. 470
Molecular Data
• The amino acid sequence of chimpanzee hemoglobin is
identical to that of humans; gorilla and rhesus monkey
hemoglobins differ from humans by 2 and 15 amino acids
• Orangutans diverged from gorilla, chimpanzee, and hominin
lines about 14 mya
• Gorillas diverged from chimpanzee and hominin lines 8 mya
• Chimpanzee and hominin lines diverged 6 to 7 mya
KEY CONCEPTS 22.2
• The study of living primates provides clues to help scientists
reconstruct the adaptations and lifestyles of early primates,
some of which were ancestors of humans
ANIMATION: Primate skeletons
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22.3 HOMININ EVOLUTION
LEARNING OBJECTIVES:
• Describe skeletal and skull differences between apes and
hominins
• Briefly describe the following early hominins: Orrorin,
Ardipithecus, and Australopithecus anamensis, A. afarensis,
and A. africanus
• Distinguish among the following members of genus Homo: H.
habilis, H. ergaster, H. erectus, H. antecessor, H.
heidelbergensis, H. neanderthalensis, and H. sapiens
• Discuss the origin of modern humans
The Human Skeleton
• The human skeleton has distinct features that reflect humans’
ability to stand erect and walk on two feet (bipedal posture)
• The curvature of the human spine provides better balance
and weight distribution for bipedal locomotion
• In humans, the shape of the pelvis and alignment of toes are
adapted for upright walking
• The foramen magnum is centered in the base of the human
skull, positioned for erect walking
Gorilla and Human Skeletons
Simply curved
spine
Foramen magnum
at the center base
of skull
Foramen magnum at
the center rear of skull
Tall, narrow pelvis
(front view)
Complex
curvature of
human
spine
Shorter, broader
pelvis (front
view)
First toe not
aligned with
others
First toe not
opposable, and
all toes aligned
Gorilla skeleton
Human skeleton
Fig. 22-7, p. 471
The Human Skull
• Relative to body size, human brains are much larger than ape
brains
• Modern human skulls lack prominent supraorbital ridges
• Human faces are flatter than those of apes, and the jaws are
shaped differently – humans have smaller teeth
Gorilla and Human Heads
Supraorbital
ridge
Incisors
Rectangular shape
(a) The ape skull has a pronounced supraorbital ridge.
Fig. 22-8a, p. 472
Incisors
U shape
(b) The human skull is flatter in the front and has a pronounced chin. The human
brain, particularly the cerebrum ( purple ), is larger than that of an ape, and the
human jaw is structured so that the teeth are arranged in a U shape. Human
canines and incisors are also smaller than those of apes.
Fig. 22-8b, p. 472
The Earliest Hominins
• Most paleoanthropologists place Sahelanthropus (6 to 7 mya)
close to the base of the human family tree
• Orrorin is an early hominin that arose about 6 mya
• Researchers studying the fossil leg bones of Orrorin think
that it walked upright and was bipedal
• Ardipithecus, Australopithecus, and Paranthropus species are
often referred to as australopithecines
• Australopithecines were bipedal, a hominin feature
Australopithecines
• The first Ardipithecus, A. kadabba, appeared about 5.8 mya
• Ardipithecus ramidus, which appeared about 4.8 mya, may
have given rise to Australopithecus anamensis, which
probably gave rise to another primitive hominin,
Australopithecus afarensis
• Many paleoanthropologists think that A. afarensis gave rise
to several australopithecine species, including
Australopithecus africanus, Paranthropus spp., and
possibly Homo habilis
Australopithecus afarensis
• A remarkably
complete 3.2-millionyear-old skeleton,
nicknamed Lucy,
was found in
Ethiopia in 1974 by a
team led by U.S.
paleoanthropologist
Donald Johanson
Fig. 22-10, p. 474
Homo habilis and Homo ergaster
• Homo habilis was the earliest known hominin with some of
the human features lacking in australopithecines, including a
slightly larger brain
• Homo habilis fashioned crude tools from stone
• The best-known fossils of H. ergaster, (2.0 to 1.4 mya) come
from Kenya
• Homo ergaster may be the direct ancestor of later humans
Homo erectus
• Homo erectus had a larger brain than H. habilis; made more
sophisticated tools; and may have worn clothing, built fires,
and lived in caves or shelters
• Homo erectus, probably a later Asian offshoot of H. ergaster,
appears to be an evolutionary dead end
Homo erectus Skull from China
Pronounced
supraorbital
ridge
Receding
forehead
Projecting
face/jaws
Fig. 22-11, p. 475
Acheulean Tool
Fig. 22-12, p. 475
Inquiring About:
THE SMALLEST HUMANS
• In 2004, fossils were
found of seven adult
humans that were about
1 m (about 3 ft) tall
• Homo floresiensis
p. 476
Archaic Humans
• Archaic humans are regionally diverse descendants of H.
ergaster that lived in Africa, Asia, and Europe 1.2 mya to
200,000 years ago
• The brains of archaic humans were essentially the same size
as our brains, although their skulls retained some ancestral
characters – they had rich and varied cultures
• Some researchers classify the oldest archaic human fossils
discovered in Europe as Homo antecessor (1.2 mya to
800,000 years ago)
Archaic Humans (cont.)
• Homo heidelbergensis (600,000 to 300,000 years ago) may
have descended from H. antecessor
• H. heidelbergensis had a larger brain – similar in size to that
of modern humans – than either H. ergaster or H. antecessor
• Many scientists think that both Neandertals and modern
humans descended from H. heidelbergensis
Neandertals
• Neandertals (250,000 to 30,000 years ago) had short, sturdy
builds; receding chins and foreheads; heavy supraorbital
ridges and jawbones; large front teeth; and nasal cavities with
triangular bony projections
• Neandertals cared for the aged and the sick, an indication of
advanced social cooperation
• They apparently had rituals, possibly of religious significance,
and sometimes buried their dead
Neandertal Tools
• Neandertal tools
(Mousterian tools)
were more
sophisticated than
those of H. erectus
Fig. 22-13, p. 477
The Disappearance of Neandertals
• The disappearance of the Neandertals about 28,000 years
ago is a mystery debated among paleoanthropologists
• Many scientists think that Neandertals were a separate
species, Homo neanderthalensis
• Analysis of Neandertal mitochondrial DNA (mtDNA) shows
that its sequence differs significantly from all modern human
mtDNA sequences
Modern Homo sapiens
• Homo sapiens, anatomically modern humans, existed in
Africa about 195,000 years ago
•
By about 30,000 years ago, anatomically modern humans
were the only members of genus Homo remaining, excluding
small, isolated populations
• Both recent fossil finds and extensive molecular analyses
have promoted the out-of-Africa model as the main
explanation for the origin of modern humans
One Interpretation of Human Evolution
Fig. 22-9, p. 473
Molecular Anthropology
• Recent genetic studies compared mtDNA, Y chromosome,
and autosomal DNA in present-day populations to ancient
DNA extracted from Neandertal and early H. sapiens remains
• These studies support the case for Africa as the birthplace of
modern humans
Human Migrations,
Based on Y Chromosome Data
LLY22
M242
M173
M343
M170
M17
M9 M201
M172, M135
M304 M96
YAP
M60
M2
M89
M168 M69
Origin
M91
M45
M174
M122
M3
M20
M130
M175
M4
M130
Fig. 22-14, p. 477
KEY CONCEPTS 22.3
• Fossil evidence indicates that the earliest human ancestors
arose in Africa and shared many features with their apelike
ancestors
• The human brain did not begin to enlarge to its present size
and complexity until long after human ancestors had evolved
bipedal locomotion
ANIMATION: Genetic distance between
human groups
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ANIMATION: Human evolution, genus homo
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22.4 CULTURAL CHANGE
LEARNING OBJECTIVE:
• Describe the impact of human culture on the biosphere
Human Culture
• At the level of our DNA sequences, we are roughly 98%
identical to gorillas and 99% identical to chimpanzees
• Human culture is not inherited in the biological sense but is
learned, largely through language
• Human culture is generally divided into three stages:
• Development of hunter–gatherer societies
• Development of agriculture
• The Industrial Revolution
Development of Agriculture
• Humans began to cultivate crops about 10,000 years ago,
resulting in a more dependable food supply and more
permanent dwellings
• Animal domestication generally followed later, which supplied
people with food, milk, and hides
• In agricultural societies, fewer people are needed to provide
food for everyone – agriculture freed some people to pursue
other endeavors, including religion, art, and crafts
The Industrial Revolution
• The Industrial Revolution (18th century) concentrated
populations in urban areas near centers of manufacturing
• The spread of industrialization increased demand for natural
resources to supply raw materials for industry
• The human population expanded so dramatically (6.8 billion in
2009) that there are serious questions about Earth’s ability to
support so many people
Humans and The Biosphere
• Human culture has resulted in large-scale disruption and
degradation of the environment
• Many species cannot adapt to the rapid environmental
changes caused by humans and are becoming extinct
• The decrease in biological diversity from species extinction is
alarming
KEY CONCEPTS 22.4
• Human culture began when human ancestors started making
stone tools