Download Ch 22 ppt

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

To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

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

To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

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

To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

ANIMATION: Human evolution, genus homo

To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

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