chapter 16: primate evolution · the main theme of this chapter is evolution. students learn how...

Products Available FromGlencoeTo order the following products,call Glencoe at 1-800-334-7344:Curriculum KitGeoKit: Earth’s HistoryVideodiscsSTV: AnimalsSTV: Biodiversity

Products Available FromNational Geographic SocietyTo order the following products,call National Geographic Societyat 1-800-368-2728:VideosThe Diversity of LifeFossils: Clues to the Past

Index to NationalGeographic MagazineThe following articles may beused for research relating to thischapter:“The Dawn of Humans:Redrawing Our Family Tree?” byLee Berger, August 1998.“Expanding Worlds: The Dawnof Humans,” by Rick Gore, May1997.“The First Steps: The Dawn ofHumans,” by Rick Gore,February 1997.

Teacher’s Corner

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Primate EvolutionPrimate Evolution

TransparenciesReproducible MastersSection

PrimateAdaptation andEvolution

Human Ancestry

Section 16.1

Section 16.2

Teacher Classroom Resources

Section Focus Transparency 39

Section Focus Transparency 40Basic Concepts Transparency 23Reteaching Skills Transparency 25

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Assessment Resources Additional ResourcesSpanish ResourcesEnglish/Spanish AudiocassettesCooperative Learning in the Science ClassroomLesson Plans/Block Scheduling

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Chapter Assessment, pp. 91-96MindJogger VideoquizzesPerformance Assessment in the Biology ClassroomAlternate Assessment in the Science ClassroomComputer Test BankBDOL Interactive CD-ROM, Chapter 16 quiz

Chapter 16 OrganizerChapter 16 Organizer

Activities/FeaturesObjectivesSection

Primate Adaptationand EvolutionNational Science EducationStandards UCP.1-5; C.3, C.4,C.6; G.2, G.3 (1 session)

Human AncestryNational Science EducationStandards UCP.2-5; A.1,A.2; C.3, C.6; E.1, E.2;G.1-3 (2 sessions)

1. Recognize the adaptations of primates.2. Compare and contrast the diversity of

living primates.3. Distinguish the evolutionary relation-

ships of primates.

4. Compare and contrast the adaptationsof australopithecines with those of apesand humans.

5. Summarize the major anatomicalchanges in hominids during human evo-lution.

Inside Story: A Primate, p. 430MiniLab 16-1: Comparing Old and New

World Monkeys, p. 433Problem-Solving Lab 16-1, p. 434Focus On Primates, p. 436Earth Science Connection: The Land Bridge

to the New World, p. 448

MiniLab 16-2: Compare Human Proteinswith Those of Other Primates, p. 439

Problem-Solving Lab 16-2, p. 443Investigate BioLab: Comparing Skulls of

Three Primates, p. 446

Section 16.2

Section 16.1

MATERIALS LIST

BioLabp. 446 metric ruler, protractor, copy ofskull diagrams of Australopithecusafricanus, Gorilla gorilla, and Homosapiens

MiniLabsp. 433 nonep. 439 calculator (optional)

Alternative Labp. 442 metric ruler or tape measure

Quick Demosp. 432 skull models or photosp. 441 video tape of sculptor doingpaleoanthropological reconstruction

Need Materials? Contact Carolina Biological Supply Company at 1-800-334-5551or at http://www.carolina.com

428A

Refer to pages 4T-5T of the Teacher Guide for an explanation of the National Science Education Standards correlations.

Reinforcement and Study Guide, pp. 69-70Concept Mapping, p. 16BioLab and MiniLab Worksheets, p. 75Laboratory Manual, pp. 109-112Inside Story PosterContent Mastery, pp. 77-80

Reinforcement and Study Guide, p. 71-72Critical Thinking/Problem Solving, p. 16BioLab and MiniLab Worksheets, pp. 76-79Laboratory Manual, pp. 113-116Content Mastery, p. 77-80Tech Prep Applications, pp. 23-24 L2

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Key to Teaching StrategiesKey to Teaching Strategies

Level 1 activities should be appropriatefor students with learning difficulties.Level 2 activities should be within theability range of all students.Level 3 activities are designed for above-average students.ELL activities should be within the abilityrange of English Language Learners.

Cooperative Learning activitiesare designed for small group work.These strategies represent student prod-ucts that can be placed into a best-workportfolio.These strategies are useful in a blockscheduling format.

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The following multimedia resources are available from Glencoe.

Biology: The Dynamics of LifeCD-ROM

Video: Primate CharacteristicsBioQuest: Biodiveristy ParkVideo: Gorilla

Videodisc ProgramPrimate Charactersitics

The Infinite VoyageThe Keepers of EdenThe Dawn of Humankind

The Secret of Life SeriesGone Before You Know It: The Biodiversity CrisisWhat’s in Stetter’s Pond: The Basics of LifeHomosapiens–Origin (a), (b)

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http://www.carolina.com

Section

What Is a Primate?Have you ever gone to a zoo and

seen monkeys, chimpanzees, gorillas,or baboons? If you have, then you’veobserved some different types of pri-mates. A primate is a group of mam-mals that includes lemurs, monkeys,apes, and humans. Primates come ina variety of shapes and sizes, but,despite their diversity, they sharecommon traits.

What characteristic accounts for thecomplex behaviors of primates? Findout by reading the Inside Story on thenext page. Perhaps the most distinc-tive trait of all primates is the roundedshape of their heads. They also havea flattened face when compared with

faces of other mammals. Fittingsnugly inside the rounded head is abrain that, relative to body size, is thelargest brain of any terrestrial mam-mal. Primate brains are also morecomplex than those of other animals.The diverse behaviors and socialinteractions of primates reflect thecomplexity of their brains.

The majority of primates are arbo-real, meaning they live in trees, andhave several adaptations that helpthem survive there. For example, theprimate skeleton is well adapted formovement among trees. All primateshave relatively flexible shoulder andhip joints. These flexible joints areimportant for climbing and swingingamong branches.

16.1 PRIMATE ADAPTION AND EVOLUTION 429

Monkeys have always fasci-nated humans, perhapsbecause of the many struc-

tural and behavioral similarities we share with them. In 1871, in his book The Descent of Man, CharlesDarwin proposed that there might bean evolutionary link among monkeys,apes, and humans. Today, scientistsexamine both living primatesand primate fossils in thesearch for information abouthow primates may haveevolved.

SECTION PREVIEW

ObjectivesRecognize the adapta-tions of primates.Compare and contrast the diversityof living primates.Distinguish the evolutionary relation-ships of primates.

Vocabularyprimateopposable thumbanthropoidprehensile tail

16.1 Primate Adaptation and Evolution

Baboons (top)and a Homohabilis skull

429

Section 16.1

BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES

Use with Chapter 16,Section 16.1

How are the chimpanzee hand and the baboon hand similar? How do they differ from the squirrel hand?

What tasks might a chimpanzee’s hand enable the animalto complete that the hand of the squirrel might not?

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Chimpanzee hand Baboon hand Squirrel hand

PrepareKey ConceptsStudents discover the sharedcharacteristics of primates. Thecharacteristics of each primategroup are explored and the evo-lution of primates is discussed.

Planning■ Obtain a human skeleton and

collect pictures or specimensof primate and nonprimatemammalian skeletons for theVisual Learning.

■ Obtain pictures or models ofprosimian and anthropoidskulls for the Quick Demo.

■ Obtain slides or videos thatshow examples of each primategroup for the Visual Learning.

1 FocusBellringer Before presenting the lesson, display Section Focus Trans-parency 39 on the overhead pro-jector and have students answerthe accompanying questions.

Assessment PlannerAssessment PlannerPortfolio Assessment

Problem-Solving Lab, TWE, p. 434Portfolio, TWE, pp. 434, 436MiniLab, TWE, p. 439BioLab, TWE, p. 447

Performance AssessmentProblem-Solving Lab, TWE, p. 443Assessment, TWE, p. 445MiniLabs, SE, pp. 433, 439

Alternative Lab, TWE, pp. 442-443BioLab, SE, pp. 446-447

Knowledge AssessmentAssessment, TWE, p. 432Section Assessments, SE, pp. 435, 445Chapter Assessment, SE, pp. 449-451

Skill AssessmentMiniLab, TWE, p. 433Assessments, TWE, pp. 435, 442Alternative Lab, TWE, pp. 442-443

428 PRIMATE EVOLUTION

Primate Evolution

What You’ll Learn■ You will compare and

contrast primates and their adaptations.

■ You will analyze the evidencefor the ancestry of humans.

Why It’s ImportantHumans are primates. A knowl-edge of primates and their evo-lution can provide an under-standing of human origins.

The Opposable ThumbIn this chapter you will studythe opposable thumb. Moveyour thumb to the palm of your hand. Now, try to pick up various shaped objects.

To find outmore about

primate evolution, visit theGlencoe Science Web Site.www.glencoe.com/sec/science

16

GETTING STARTEDGETTING STARTED

ChapterChapter

Humans are not the onlyanimals that constructand use tools. This chim-panzee has broken off atwig to use like a fishingpole to catch termites, afavorite food.

428

Theme DevelopmentThe main theme of this chapteris evolution. Students learn howthe availability of human fossilsand archaeological evidenceaffect the development of hypo-theses about human evolution.Another theme, unity withindiversity, is developed throughdescriptions of shared primatecharacteristics.

Chapter 16Chapter 16

MultipleLearningStyles

Look for the following logos for strategies that emphasize different learning modalities.Kinesthetic Getting StartedDemo, p. 428; Project, p. 440Visual-Spatial Biology Journal,p. 432; Portfolio, p. 434;

Meeting Individual Needs, p. 434;Reteach, pp. 435, 445; Quick Demo,p. 441; Enrichment, p. 444

Interpersonal Project, pp. 437,444

Intrapersonal Biology Journal,p. 430; Meeting Individual

Needs, p. 433Linguistic Meeting IndividualNeeds, pp. 437, 444; Biology

Journal, p. 441Logical-Mathematical Portfolio,p. 436; Going Further, p. 447Naturalist Extension, p. 435

GETTING STARTED DEMOGETTING STARTED DEMO

Kinesthetic Instruct stu-dents to pick up pencils

without using their thumbs,and use them to write theirnames. Then, ask students todescribe how their thumbsdiffer from their other fingers.P

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If time does not permit teach-ing the entire chapter, use theBioDigest at the end of theunit as an overview.

http://www.glencoe.com/sec/science

Primate hands and feet are uniqueamong mammals. Their digits, fin-gers and toes, have nails rather thanclaws and their joints are flexible. Inaddition, primates have an adaptiveopposable thumb—a thumb thatcan cross the palm to meet the otherfingertips. Opposable thumbs enableprimates to grasp and cling toobjects, such as the branches of trees,Figure 16.1. They also enable pri-mates to manipulate tools.

Primates have a highly developedsense of vision, called binocularvision. Primate eyes face forward sothat they see an object simultane-ously from two viewpoints. This eyepositioning enables primates to per-ceive depth and thus gauge distances.As you might imagine, this type ofvision is helpful for an animal jump-ing from tree to tree. Primates alsohave color vision that aids depth per-ception, enhances their ability todetect predators, and helps them findripe fruits.

Primate OriginsThe similarities among the many

primates is evidence that primatesshare an evolutionary history.Scientists use fossil evidence andcomparative anatomical, genetic, and

biochemical studies of modern pri-mates to propose ideas about howprimates are related and how theyevolved. Biologists classify primatesinto two major groups: prosimians andanthropoids, as shown in Figure 16.2.

Prosimianlike primates evolved first

Prosimians are small, present-dayprimates that include, among others,the lemurs, aye-ayes, and tarsiers.Most prosimians have large eyes andare nocturnal. They live in the tropi-cal forests of Africa and SoutheastAsia, where they prowl through theleafy canopy in search of insects,seeds, and small fruits. The earliest


Figure 16.1Notice the thumb ofthe chimpanzee. Anopposable thumbhelps a primate graspand cling to objectsand manipulatethem.

Figure 16.2Primates are dividedinto two groups: theprosimians and theanthropoids, whichare subdivided into monkeys and hominoids.

Primate Ancestors

Anthropoids

Hominoids

New world monkeys Tarsiers

Lemurs

Lorises, Pottos, and Galagos

African apesOrangutans

Gibbons

Humans

Old world monkeys

Hominids

Prosimians

OriginWORDWORD

anthropoidFrom the Greekwords anthropos,meaning “man,”and eidos, meaning“shape.” Theanthropoid apesresemble humans in their generalappearance.

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A Primate

Primates are a diverse group of mammals, but they sharesome common features. For example, you can see in the

drawing of an orangutan that primates have rounded headsand flattened faces, unlike most other groups of mammals.

Critical Thinking Why would binocular vision be an adaptive advantage for primates?

Orangutans

INSIDESSTORTORYY

INSIDE

Brain volume A primate’sbrain volume is large relativeto its body size. The complexbehaviors of a primate reflect its large brain.

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Vision Vision is thedominant sense in a primate. In addition togood visual perception,a primate has binocularvision, which provides itwith a stereoscopic viewof its surroundings.

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Opposable thumbs The primate’sopposable thumbs enable it to graspand manipulate objects. The thumb isalso flexible, which increases the pri-mate’s ability to manipulate objects.

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Arm movementThe shoulders of a primate are adaptedfor arm movement indifferent directions.Flexible arm move-ment is an importantadvantage for arbo-real primates.

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Flexible joints The flexiblejoint in a primate’s elbow allows the primate to turn itshand in many directions.

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Feet A primate’s feet can graspobjects. However, modern primateshave different degrees of efficiencyfor grasping objects with their feet.

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2 Teach

PurposeStudents examine traits commonto primates.

Teaching Strategies■ Ask students why primates arepopular zoo attractions and whatmakes primates unique. Listresponses on the chalkboard.■ Remind students that humansare primates and, although notarboreal, share these adaptations.■ Discuss each major primatecharacteristic, having studentsexplain how each is an importanthuman adaptation.

Visual Learning■ Display pictures or specimens

of primate (including human)and other mammalian skele-tons and teeth to compare andcontrast them.

■ Show how a human skeleton’shands, feet, and joints are sim-ilar to those of other primates.

Critical ThinkingBinocular vision allows primatesto judge depth, a useful adapta-tion for arboreal species.

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Observing a Primate Intrapersonal Have students findthe scientific name of a primate

they have seen and then write answers tothe following questions: Where did youfirst see the primate? What was it doing?What about the primate interested you?What more about the primate would youlike to learn?

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P R O J E C TInterpreting BehaviorPaleoanthropologists use a variety of meth-ods to interpret primate behavior from fossilevidence. Have student groups report onone of the following methods:■ Analyzing the wear on teeth to learn

what extinct primates ate

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■ Using cladistics to determine phylogeny

■ Analyzing muscle function in living pri-mates

Student reports should include one or twoexamples of how the method answered aquestion about primate evolution.

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IINSIDENSIDESSTORTORYY

INSIDE

VIDEODISCBiology: The Dynamicsof Life

Primate Characteristics (Ch. 7) Disc 1, Side 2, 47 sec.

CD-ROMBiology: The Dynamicsof Life

Video: Primate CharacteristicsDisc 2

!7rÖ"

Concept DevelopmentPrimate hands are divided intothree regions: the carpus, themetacarpus, and the phalanges.Point out each region anddescribe its anatomy. Explain thatthe wrist consists of eight or ninebones aligned in two rows.Between the two rows is the mid-carpal joint that provides flexibil-ity. The joints at the juncture ofthe metacarpals and most pha-langes lack mobility. The joint atthe thumb’s base is extremelymobile.

Then, remind students that,although most primate handshave the same numbers of bones,the relative bone sizes vary withthe species’ needs for locomotionor manipulation. For example,the slow-climbing loris has astrong thumb and long, lateraldigits for grasping branches. Incontrast, gibbons and spidermonkeys have long, slender digitsthat function almost like hooks asthey hang under branches.

Internet Address Book

Note Internet addressesthat you find useful in

the space below for quick reference.

Resource ManagerResource Manager

Section Focus Transparency 39and Master

Laboratory Manual, pp. 109-112 L2

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Concept Mapping, p. 16

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skeletal features, such as a more orless upright posture, than prosimians.

Monkeys are classified as NewWorld monkeys or Old World mon-keys. Try the MiniLab to comparesome characteristics of these twogroups of monkeys.

New World monkeys, which livein the rain forests of South Americaand Central America, are all arboreal.A long, muscular prehensile tail(pree HEN sul), characterizes many ofthese primates. They use the tail as afifth limb, grasping and wrapping itaround branches as they move fromtree to tree. Among the New Worldmonkeys are tiny marmosets andlarger spider monkeys.

Old World monkeys are generallylarger than New World monkeys.They include the arboreal monkeys,such as the colobus monkeys andguenons, the terrestrial monkeys,such as baboons, and monkeys, suchas macaques, which are equally athome in trees or on the ground. OldWorld monkeys do not have prehen-sile tails. They are adapted to manyenvironments that range from thehot, dry savannas of Africa to thecold mountain forests of Japan.

Hominoids are classified as apes orhumans. Apes include gibbons,orangutans, chimpanzees, bonobos,and gorillas. Apes lack tails and havedifferent adaptations for arboreal lifefrom those of the prosimians andmonkeys. For example, apes havelong, muscled forelimbs for climbingin trees and swinging from branches.


Comparing Old and NewWorld Monkeys In thisactivity, you will gather andthen compare data aboutOld World monkeys andNew World monkeys.

Procedure! Copy the data table.@ Examine the diagrams.# Complete the data

table.

Analysis1. Why would a low body

weight be helpful for ananimal with an arboreallife style?

2. Which group appears tobe more closely relatedto humans? Explainyour answer. (Note:Humans have eight pre-molars, twelve molars,and a total of 32 teeth.)

MiniLab 16-1MiniLab 16-1 Comparing and Contrasting

New WorldMonkey

Premolars

Molars

Old WorldMonkey

Nostrils far apartand open up

Tail can grasp Tail cannot grasp

Nostrils closeand open down

CharacteristicOld World monkey

New World monkey

Number ofpremolars ( jaw)

Number of molars ( jaw)

Total teeth in mouth

Nostril position

Tail

Body weight 0.14 to 11 kg 1.2 to 30 kg

Data TableGibbons aresmall apes thatlive in SoutheastAsia. They havelong arms andlong, curved fingers.

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Purpose Students will compare and con-trast traits of Old World andNew World monkeys.

Process Skillscompare and contrast, analyzeinformation, draw a conclusion,think critically

Teaching Strategies■ Explain the meaning of theterm “prehensile.”■ Review the number and typeof human teeth. Ask students tocount their teeth. Discuss anydifferences, such as uneruptedmolars.■ Use photos of Old World andNew World monkeys to illustratetheir nostrils.

Expected ResultsNumber of premolars (1/4 jaw)=3, 2; number of molars (1/4jaw)=3, 3; total teeth in mouth=36,32; nostril position=up, down;tail=prehensile, not prehensile.

Analysis1. It would allow for efficient

movement in trees.2. Old World monkeys share

more traits with humans.

Skill Ask students to visita zoo and determine if the mon-keys are Old World or NewWorld by their features. Use thePerformance Task AssessmentList for Making Observations andInferences in PASC, p. 17. L2

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AssessmentAssessment

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MiniLab 16-1MiniLab 16-1

fossils of prosimians are about 50 to55 million years old.

Some scientists consider fossils ofan organism called Purgatorius to bethe earliest of primate fossils.Purgatorius, which probably resem-bled a squirrel, was a prosimianlikeanimal that lived about 66 millionyears ago. Although there are no liv-ing species of Purgatorius, present-day prosimians, Figure 16.3, areprobably quite similar.

Humanlike primates evolveHumanlike primates are called

anthropoids (AN thruh poydz).Anthropoids, some of which areshown in Figure 16.4, include mon-keys and hominoids. In turn, homi-noids include apes and humans.Many features distinguish anthro-poids from prosimians. In particular,anthropoids have more complexbrains than prosimians. Anthropoidsare also larger and have different


Figure 16.4Monkeys and homi-noids are classifiedas anthropoids.

Figure 16.3Most prosimians aresmall, nocturnal animalsthat live in tropical environments.

Golden liontamarins arearboreal NewWorld mon-keys that live inSouth America.

AA

This mandrill is an Old Worldmonkey that lives in the forestsof West Africa, and spendsmost of its time on the ground.

BB

AA The aye-aye, aprosimian found in Madagascar,uses its long middle finger to dig for grubs.

BB Tarsiers are prosimians that livein the Philippines, Borneo, andSumatra.

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Knowledge Have studentswrite an essay about how theirlives would be affected if theirshoulder and hip joints movedonly back and forth, like those ofdogs and horses.

Tying to PreviousKnowledgeReview the environmental condi-tions and the types of organismsliving in the early Cenozoic Era,when primates evolved. Remindstudents that many mammaliangroups diversified at this time.Discuss how these factors mayhave influenced primate evolu-tion.

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Cartoon EvolutionVisual-Spatial Ask students to col-lect some cartoons that relate to

human evolution. Have them work ingroups to develop their own cartoons.

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MEETING INDIVIDUAL NEEDS MEETING INDIVIDUAL NEEDS

GiftedIntrapersonal Many unansweredquestions about primate evolution

remain. Have students report on one ofthe following topics.■ What group gave rise to the primates?■ What is the phylogeny of tarsiers?■ How did New World monkeys reach

South America?

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Quick DemoQuick Demo

Use photos, illustrations, mod-els, or actual skulls to show thedifferences between prosimiansand anthropoids. For example,contrast the fused frontal boneof anthropoids to the unfusedone of prosimians.

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VIDEODISCThe Infinite Voyage:The Keepers of Eden

Extinction and the National Zoo’sTamarin Monkey Project (Ch. 4)13 min. 30 sec.

!7KVF"

Training AnimalsAsk students to suppose that they trainanimals for people who have visual, audi-tory, and physical challenges. Have themlist the tasks that they could train mon-keys, but not dogs, to perform.

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VIDEODISCGTV: Planetary ManagerAnimal, Side 2

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Figure 16.6Modern apes are diverse,and fossils indicate thatancient apes were evenmore diverse. Orangutansare arboreal apes that livein the forests of Borneoand Sumatra (a). Gorillasare ground-dwellingAfrican apes that live insmall social groups (b).

Section AssessmentSection Assessment

Understanding Main Ideas1. What adaptations help primates live in the trees?2. Describe how hominoids are classified.3. What features distinguish anthropoids from

prosimians?4. What is the major physical difference between

Old World monkeys and New World monkeys?

Thinking Critically5. Imagine you are a world famous primatologist, a

scientist who studies primates. An unidentified,

complete fossil skeleton arrives at your lab. You suspect that it’s a primate fossil. What observations would you make to determine if your suspicions are accurate?

6. Classifying Make a table listing the differenttypes of primates, key facts about each group,and how the groups might be related. For morehelp, refer to Organizing Information in the Skill Handbook.

SKILL REVIEWSKILL REVIEW

to this climatic cooling. Fossils indi-cate how the apes adapted and diver-sified. You can see the modern-daydiversity of apes in Figure 16.6.

Remember that hominoids includethe apes and humans. By examiningthe DNA of each of the modern homi-noids, scientists have evaluated theprobable order in which the differentapes and humans evolved. From thistype of evaluation, it appears thatgibbons were probably the first apesto evolve, followed by the orangutansthat are found in southeast Asia.Finally, the African apes, chim-panzees, and gorillas evolved. Someanthropologists suggest that one ofthe groups of African apes was theancestor of modern humans.

can see the worldwide geographicdistribution of monkeys and apes.

Old World monkeys probablyevolved more recently than NewWorld monkeys. Scientists suspectthis is true because the oldest fossilsof Old World monkeys are only about20 to 22 million years old. The fossilsindicate that the earliest Old Worldmonkeys were arboreal like today’sNew World monkeys.

Hominoids evolved in Asia and Africa

According to the fossil record, therewas a global cooling when the homi-noids evolved in Asia and Africa. Atabout the same time, the Old Worldmonkeys evolved and became adapted

a

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3 AssessCheck for UnderstandingHave students write the sharedcharacteristics of primates anddescribe beside each its adaptivesignificance.

ReteachVisual-Spatial Give studentsoutline maps of the world.

Have them develop a key to showwhere the groups of primateslive.

ExtensionNaturalist Have studentsprepare a primate phyloge-

netic tree that contains the nameof each primate group, when thegroup evolved, and the group’sunique characteristics.

Skill Have students createin their journals a diagram thatshows the possible evolutionaryrelationships of the primategroups.

4 CloseDiscussionReview the highlights of primateevolution. Have students identifythe major evolutionary develop-ments. L1

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Section AssessmentSection AssessmentSection Assessment1. Opposable thumbs, digits with nails, and

flexible feet help primates grip branches.Flexible skeletons and binocular visionenable them to gauge depth and distance.

2. Hominoids are classified as apes orhumans.

3. Anthropoids have larger brains, differentskull and skeletal structures, and largersizes than prosimians.

4. New World monkeys have prehensiletails. Old World monkeys are generallylarger and lack prehensile tails.

5. Observations could include the presenceof an opposable thumb, a large brainsize, nails rather than claws, binocularvision, and flexible joints.

6. Check student lists for accuracy andunderstanding of the main concepts.

Although many apes are arboreal,most also spend time on the ground.Gorillas, the largest of the apes, livein social groups on the ground.Among the apes, social interactionsand long-term parental care indicatea large brain capacity.

Humans have an even larger braincapacity and walk upright. You willread more about human primates inthe next section. Anthropologistshave suggested that monkeys, apes,and humans share a common anthro-poid ancestor based on their struc-tural and social similarities. Use theProblem-Solving Lab to explore thisidea. The oldest anthropoid fossilsare from Africa and Asia and date toabout 37 to 40 million years ago.

Anthropoids evolved worldwideThe oldest monkey fossils are of

New World monkeys and are 30 to35 million years old. Although NewWorld monkeys probably share acommon anthropoidlike ancestorwith the Old World monkeys, theyevolved independently of the OldWorld monkeys because of geo-graphic isolation. In Figure 16.5, you


New WorldMonkeys

Gorillas

Old WorldMonkeys

Gibbons

Chimpanzees

Figure 16.5The present-day,worldwide distri-bution of monkeysand apes suggeststhat they probablyevolved a longtime ago from acommon ancestor.

How do primate infants and adults compare? Someinfant primates, such as macaques, cling to their mothers fortheir first few months of life. Therefore, muscles associatedwith clinging may represent a higher percentage of totalbody weight in infant macaques than in adult macaques.

AnalysisThe graph shows the percentages of body weight for

specific body parts of adult and infant macaques.

Thinking Critically1. Explain the difference between the percentage of body

weight of infant heads and adult heads.2. Explain why the percentage of body weight for hands and

feet change as macaques mature. Would you expect thesame pattern in humans? Explain your answer.

Problem-Solving Lab 16-1Problem-Solving Lab 16-1 Using Numbers

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Infant Macaque

Macaque Body Weight Percentages

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Purpose Students will observe that theweights of several body regionsof an infant and adult primatecorrelate with different percent-ages of their body weights.

Process Skillsanalyze information, compareand contrast, draw a conclusion,make and use graphs, think criti-cally, use numbers

Teaching Strategies■ Explain to students that non-human infant primates typicallygo everywhere with their mother,clinging at first to her belly, andlater to her back.■ Remind students that, unlike aprimate’s other organs, its braindoes not grow much after birth.

Thinking Critically

1. Major changes in brain sizedo not occur during growth.

2. The percentage decreasesbecause the need for strongmuscles to continually grasptheir mothers diminishes.No. Human infants do notcling to their mothers.

Portfolio Ask students toprepare a graph similar to the onethey just used. The graph shouldcompare the percent body weightsfor a human infant and adult. Usethe Performance Task AssessmentList for Graph from Data inPASC, p. 39.

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Problem-Solving Lab 16-1Problem-Solving Lab 16-1

PortfolioPortfolio

Ape and Baboon EvolutionVisual-Spatial Have students drawthe probable events in baboon and

ape evolution. Their illustrations shouldinclude the time period and the environ-mental factors that may have influencedape and baboon evolution.P

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Learning DisabledVisual-Spatial Give students pho-tographs, illustrations, or videos of

each group of primates. Have studentswrite the names of each group and atleast five of its characteristics in their jour-nals. Then, have students review their liststo compare and contrast the characteris-tics.

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Reinforcement and StudyGuide, pp. 69-70

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NEW WORLD MONKEYSUnlike their Old World counter-parts, New World monkeys haveprehensile tails. Sometimes com-pared to an extra hand, the tail canwrap around a tree limb and sup-port the monkey’s weight. Thus,the animal can dangle upsidedown to eat. The capuchins(above) of Central and SouthAmerica have thumbs that can move to touchother fingers and helpthem pick up food.

Unlike monkeys, apes have no tails, andthey are usually larger than monkeys.While monkeys run on all fours, apes walkon two legs with support from their hands.Chimpanzees (left), gibbons, gorillas, andorangutans (above) are all apes. Living inAfrica and Asia, these primates have largebrains and are considered to be more likehumans than any other animal. They aresubject to many of the same diseases ashumans, can use simple tools, and somehave been taught to communicate withhumans using sign language.

APES

▼

1 THINKING CRITICALLY Examine the photo of New Worldmonkeys. How is having a tail an adaptive advantage forthese primates?

2 COMPARING AND CONTRASTING Which of the species in thisfeature probably live in trees? Explain your answer.

EXPANDING Your View

ORANGUTAN

CAPUCHINS

CHIMPANZEE

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Visual Learning■ Prepare a video or slide pre-

sentation of one or morespecies of each primate groupto provide detail about thegroups’ behaviors and ecolo-gies.

■ Show pictures of primate fos-sils and discuss how each fossilprovides evidence of primateevolution.

Answers to Expanding Your View

1. The tail aids in balance andallows them to grasp a branchand keep their hands free.

2. Long-tailed primates proba-bly live in trees: prosimians,New World monkeys, andsome Old World monkeys.

Monkeys foundin Europe, Asia,and Africa arecalled OldWorld monkeys.They grow larg-er than theirNew World rela-tives and haveno prehensiletail for grasping.

Pads of tough skin on their rumps cushion them while they are seated. Among Old World monkeys, the mandrill (above) wins the prize for the most colorful face. The Japanese macaque (right), or snow monkey, lives farther north than any other species of monkey.

PROSIMIANSThese small, tree-dwelling prosim-inans look least like other pri-mates. Their triangular faces, setoff by large round eyes,lack muscles needed tomake facial expressionsthat other primates use forcommunication. They canbe as small as a mouse oras big as a large house cat.Perhaps the best knownprosimians are the lemurs (right),which live only in Madagascar andneighboring islands off the coast ofeastern Africa.

OLD WORLD MONKEYSCatch the gaze of anorangutan and you’ll bestaring into a face very muchlike your own. Similaritiesbetween apes and humansare striking—expressiveeyes, fingers that can grasp,keen intelligence, and com-plex social systems. Theresemblance is no coinci-dence. Apes and other pri-mates are humans’ closestrelatives. The Primate orderis made up of 13 families,including Hominidae, towhich Homo sapiens, ourspecies, belongs.

PrimatesRING-TAILED LEMUR

JAPANESE MACAQUES

FOCUS ON

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MANDRILL

SQUIRREL MONKEY

AYE-AYE

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Focus OnPrimatesPurpose Students will learn about thecharacteristics of the major pri-mate groups.

BackgroundBy investigating the functionalrelationships between primatefeatures, such as size, tooth struc-ture, bone shape, and behavioralhabits, the probable evolution ofmany anatomical differences canbe better understood.

Teaching Strategies■ Discuss the characteristics ofeach group, emphasizing howeach adaptation is important forits environment.■ Guide students to hypothesizehow natural selection may haveaffected the groups’ evolution.■ Discuss some of the methodsused to analyze primate fossils,such as biomechanical studies toinfer locomotion and scanning-electron microscopy to infer diet.

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Fossil Problems Logical-Mathematical Have studentssolve the following problems.

■ A fossil skeleton of a primate known asApidium is discovered in Egypt. It is 31million years old and shows similarities toNew World monkeys. Could this animalbe an ancestor of New World monkeys? Itis unlikely because the fossil is from the

same period when the New World mon-keys evolved.

■ A jaw fragment discovered in easternAfrica is 8 million years old. Scientists sug-gest that it might be from the commonancestor of African apes and humans.What tests might you perform to verifythis idea? analysis of skeletal structuresand brain size PP

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PortfolioPortfolio P R O J E C TAll About a Primate

Interpersonal Have student groupsmake presentations about particu-

lar species of primates. Presentations canbe models, posters, videos, or skits andmust include behavior, anatomy, ecology,taxonomy, evolution, and importance tohumans.

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English Language LearnersLinguistic Have students define thefollowing terms: opposable thumb,

binocular vision, prosimian, anthropoid,and ape. Have students circle the word inthe following group that does not belong:New World monkey, opposable thumb,Old World monkey, ape, prosimianP

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BioQuest: BioDiversity ParkDisc 3, 4

VIDEOTAPEThe Secret of Life

Gone Before You Know It: TheBiodiversity Crisis


Video: GorillaDisc 4

Therefore, apes with the ability towalk upright better and more oftenthan others probably survived moresuccessfully on the ground and livedto reproduce and pass the character-istic to offspring. According to thisreasoning, the bipedal organisms thatevolved might have been the earliestforms of a hominid.

Although the fossil record isincomplete, more hominid fossils arefound every year. The many fossilsthat scientists have found revealmuch about the anatomy and behav-ior of early hominids. Fossils of skullsprovide scientists with informationabout the appearance and braincapacity of the early hominid types.Complete the BioLab at the end ofthe chapter to learn more about thekinds of information scientists gatherfrom skulls of hominids.

Early hominids walked uprightIn Figure 16.7, you see a South

African anatomist, Raymond Dart,who, in 1924, discovered a skull of a

Figure 16.7Raymond Dart discovered the first aus-tralopithecine fossil, the Taung child,Australophithecus africanus. The skullhas features of both apes and humans.

16.2 HUMAN ANCESTRY 439

MiniLab 16-2MiniLab 16-2 Analyzing Information

PrimatePercent difference

Amino acids differentfrom humans

Baboon

Chimpanzee

Gorilla

Lemur

Data Table

Compare Human Proteins with Those of Other PrimatesScientists use differences in amino acid sequences in proteinsto determine the evolutionary relationships of living species.In this activity, you’ll compare representative short sequencesof amino acids of a protein among groups of primates todetermine their evolutionary history.

Procedure! Copy the data table.@ For each primate listed in the table above, determine

how many amino acids differ from the human sequence.Record these numbers in the data table.

# Calculate the percentage differences by dividing the num-bers by 15 and multiplying by 100. Record the numbers inyour data table.

Analysis1. Which primate is most closely related to humans? Least

closely related?2. Construct a diagram of primate evolutionary relationships

that most closely fits your results.

Baboon Chimp Lemur Gorilla Human

ASNTHRTHRGLYASPGLUVALASPASPSERPROGLYGLYASNASN

SERTHRALAGLYASPGLUVALGLUASPTHRPROGLYGLYALAASN

ALATHRSERGLYGLULYSVALGLUASPSERPROGLYSERHISASN



Table 16.1 Aminio Acid Sequences in Primates

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Purpose Students will learn how compar-ing amino acid sequences indi-cates phylogenetic relationships.

Process Skillscompare and contrast, make anduse tables, interpret data

Teaching Strategies■ Explain the molecular and bio-chemical methods used to deter-mine phylogeny.

Expected ResultsThe human, chimpanzee, andgorilla sequences are identical.Baboons differ by 33 percent andlemurs by 47 percent.

Analysis1. gorilla and chimpanzee;

lemur2. Baboons should branch off

lemurs. Gorillas, chimpan-zees, and humans should beclose together.

Portfolio Ask students tosummarize this activity. Havethem predict the results of analyz-ing another protein. Use thePerformance Task AssessmentList for Lab Report in PASC, p. 47 PP

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MiniLab 16-2MiniLab 16-2

Section


HominidsSome scientists propose that

between 5 and 8 million years ago inAfrica, a population that was ances-tral to the African apes and humansdiverged into two lines. According tothis hypothesis, one line evolved intothe African apes—gorillas and chim-panzees. The other line evolved intomodern humans. These two lines arecollectively called the hominids (hohMIHN udz)—primates that can walkupright on two legs and includegorillas, chimpanzees, bonobos, andhumans. Hominids do not includethe other types of apes—the gibbonsand orangutans.

There are relatively few fossils tosupport this hypothesis, but DNA

studies of the modern hominids pro-vide data that support the idea. Youcan work with some of these data inthe MiniLab on the next page.

Some anthropologists suggest thatthe divergence of the African popula-tion of ancestral hominids mighthave occurred in response to envi-ronmental changes that forced someancestral apes to leave their treetopenvironments and move onto theground to find food. In order tomove efficiently on the ground whileavoiding predators, it was helpful for the apes to be bipedal, meaningable to walk on two legs. In additionto speed, walking on two legs leaves the arms and hands free for otheractivities, such as hunting, feeding,protecting young, and using tools.

What would it be like to discover anancient primate skull? Well,you’d probably have to spend

weeks at the excavation site brushing smallsections of the area each day. Some daysyou’d find a piece of bone; other days youwouldn’t. After weeks of tedious labor, youmight be ready to assemble the pieces ofbone in your laboratory. After more weeks of work, you might finally be looking into the empty orbits of a very human-looking skull that generates more questions than answers. What organism was this? How did it live?

SECTION PREVIEW

ObjectivesCompare and contrastthe adaptations of australopithecines withthose of apes andhumans.Summarize the majoranatomical changes inhominids during humanevolution.

VocabularyhominidbipedalaustralopithecineNeanderthalCro-Magnon

16.2 Human Ancestry

An australopithecinereconstruction(above) and an australopithecineskull

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Section 16.2

PrepareKey ConceptsStudents will study the archaeo-logical evidence of human evolu-tion. They will investigate ideasabout the behavior of differentgroups of probable human ances-tors and how cultural adaptations,such as the use of tools, fire, andlanguage, may have originated.

Planning■ Gather several round stones to

use as tools for the Project.

1 FocusBellringer Before presenting the lesson, display Section Focus Trans-parency 40 on the overhead pro-jector and have students answerthe accompanying questions.

BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES

Use with Chapter 16,Section 16.2

What do these skeletons suggest about the way eachorganism moved?

How might the australopithecine be better suited thanthe gorilla for using tools?

11

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Gorilla

Australopithecine

Cultural DiversityThe Hominid Gang

Linguistic Finding human fossils is dif-ficult and requires considerable exper-

tise. Introduce the contributions of Kenyanfossil expert Kamoya Kimeu, the leader of ateam of fossil hunters known as the HominidGang. Since the 1960s, Kimeu’s work has ledto the discovery of many important hominid

fossils, including “Lucy” and the 12-year-oldHomo erectus male, the “Strapping Youth.”

Have students read sections from OriginsReconsidered by Richard Leakey and RogerLewin or other similar books to learn moreabout Kimeu and the techniques involved infinding human fossils. L3

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VIDEODISC The Infinite Voyage:The Dawn of Humankind, DatingFossils: Effects of Dating Methods

and Interbreeding Theories(Ch. 5) 4 min.!7U`H"

DNA Studies Create Controversy (Ch. 7) 3 min. 30 sec.!7itB"

The BioLab at theend of the chaptercan be used at thispoint in the lesson.

INVESTIGATEINVESTIGATE


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Resource ManagerResource ManagerSection Focus Transparency 40 and

MasterLaboratory Manual, pp. 113-116 L2

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You may be wondering what lifewas like for hominids like Lucy.Because of the combination of ape-like and humanlike features, one ideais that A. afarensis and other speciesof australopithecines might havelived in small family groups, sleepingand eating in trees. But, to travel,they walked upright on the ground.The fossil record indicates that an A. afarensis individual rarely survivedlonger than 25 years.

In addition to fossils of A. afarensisand A. africanus, fossils of two, orperhaps three, other species of aus-tralopithecines have been found.These other species, discovered atsites in East Africa and South Africa,are dated about 1 to 2.5 million yearsold. Overall, the later species aresimilar to the earlier ones. However,these later hominids are grouped intothe genus Paranthropus because theirfossils suggest that the individualswere more robust and had largerteeth and jaws than earlier species.

The evolutionary relationshipsamong australopithecines are not clearfrom the fossil record. However, thegenus disappears from the record atabout 1 million years ago. Althoughaustralopithecines became extinct,some paleoanthropologists proposethat an early population of thesehominids might have been ancestralto modern hominids.

The Emergence ofModern Humans

Any ideas about the evolution ofmodern hominids must include howbipedalism and a large brain evolved.Australopithecine fossils provide sup-port for the idea that bipedalismevolved first. But when did a largebrain evolve in a hominid species?When did hominids begin to usetools and develop culture?

Early members of the genus Homo madestone tools

In 1964, anthropologistsLouis and Mary Leakey,Figure 16.9, describedskull portions belonging toanother type of hominid inTanzania, Africa. Thisskull was more humanlike than thoseof australopithecines. In particular,the braincase was larger and the teethand jaws were smaller, more likethose of modern humans. Because ofthe skull’s human similarities, theLeakeys classified the hominid withmodern humans in the genus Homo.Because stone tools were found nearthe fossil skull, they named thespecies Homo habilis, which means"handy human."

Radiometric dating indicates thatHomo habilis lived between about 1.5 and 2 million years ago. It is theearliest known hominid to make anduse stone tools. These tools suggestthat Homo habilis might have been ascavenger who used the stone tools tocut meat from carcasses of animalsthat had been killed by other animals.


Figure 16.9Louis and MaryLeakey discov-ered many fossilsin the OlduvaiGorge area ofTanzania, Africa.

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Misconception“Why, if humans evolved fromapes, are there still apes alivetoday?” This question representsa common misconception thatstudents have about human evo-lution. Explain that humansevolved from ancestors of apes,which were neither humans norapes. Reiterate that the commonancestor of the two groups prob-ably lived in the Miocene period.

Using Science TermsReinforce the idea that Homohabilis, meaning “handy man,”was so named because evidenceindicates that this hominid usedtools. Have students correlatethis with the term handymantoday as it refers to people whouse tools to make household ormechanical repairs.

young hominid with an apelike brain-case and facial structure. However,the skull also had an unusual featurefor an ape skull—the position of theforamen magnum, the opening in theskull through which the spinal cordpasses as it leaves the brain.

In the fossil, the opening waslocated on the bottom of the skull, asit is in humans but not in apes.Because of this feature, Dart proposedthat the organism had walkedupright. He classified the organism asa new primate species, Australopithecusafricanus (aw stray loh PIHTH uh kus •af ruh KAHN us), which means“southern ape from Africa.” Theskull that Dart found has been datedat about 1 to 2 million years old.

Since Dart’s discovery, paleoan-thropologists, scientists who studyhuman fossils, have recovered manymore australopithecine specimens.They describe an australopithecineas an early hominid that lived inAfrica and possessed both apelike andhumanlike characteristics.

Early hominids: Apelike and humanlike

Later, in East Africa in 1974, anAmerican paleoanthropologist,Donald Johanson, discovered anearly complete australopithecineskeleton that he called "Lucy" after a popular song of the time.Radiometric dating shows that Lucyprobably lived about 3.5 millionyears ago. Johanson proposed thatthe Lucy skeleton was a new species,Australopithecus afarensis. Other fossilsof A. Afarensis indicate that thisspecies probably existed between 3and 5 million years ago, making it theearliest known hominid species.

Although the fossils show that A. afarensis individuals had ape-like shoulders and forelimbs, thestructure of the pelvis, as shown in Figure 16.8, indicates that these individuals were bipedal, likehumans. On the other hand, the sizeof the braincase suggests that theirbrains had a small, apelike volumeand not a larger human volume.


Figure 16.8Some skeletal featuresof an australopithecineare intermediatebetween those ofmodern apes andhumans. Compare theskull and pelvic boneof Australopithecusafarensis (b) withthose of the chim-panzee (a) and thehuman (c).

OriginWORDWORD

paleoanthropologyFrom the Greekwords paleo, meaning“ancient,” anthropo,meaning “human,”and logos, meaning“study.”Paleoanthropology is the study of human fossils.

ChimpanzeePan Troglodytes

Ancient HominidAustralopithecus afarensis

HumanHomo Sapiens

Ischialtuberosity

Acetabulum

Ilium

Ischialtuberosity

Ilium

Ischialtuberosity

Ilium

Acetabulum Acetabulum

a b c

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Chalkboard ActivityVisual-Spatial On a sectionof the chalkboard that you

do not have to erase for a while,begin a time line of hominid tohuman evolution as it is describedin this section. Encourage stu-dents to insert the time periods,such as 3-5 million years ago forA. afarensis, on the time line asthey read about each group.

Visual LearningFigure 16.8 Discuss the observ-able differences in the three setsof bones. Ask students what char-acteristics A. afarensis shared withhumans. bipedal What character-istic is apelike? the jawbone and thesize of the facial area

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P R O J E C TUsing Stone Tools

Kinesthetic Provide groups of studentswith simple stone tools and have them

put on lab aprons and safety goggles. Youcan make the tools from quartz or flintstones. Hit one stone against the other toremove flakes and then use both the flakes

and the cores as tools. Have students designexperiments to test the effectiveness of thetools for different tasks, such as cuttingmeat, cutting branches, or breaking openfresh beef bones. Have them write a reportof their findings.

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VIDEODISCThe Infinite Voyage: TheDawn of Humankind,

Human Origins: Unexpected Finds in South Africa (Ch. 6) 5 min.

!7_jJ"


Australopithecines in PrimateEvolution

Linguistic Have students write a shortessay about the significance of aus-

tralopithecines in primate evolution. Theycan conclude their essays with some unan-swered questions about australopithecines.L2

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Recent DiscoveriesLinguistic Have students research cur-rent hominid discoveries, the evolution

of human speech, or the relationshipbetween Neanderthals and Cro-Magnons.Have them write a summary of their find-ings.

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VIDEOTAPEThe Secret of Life

What’s in Stetter’s Pond: TheBasics of Life

Quick DemoQuick Demo

Visual-Spatial Show stu-dents videos that describe

how sculptors help paleoan-thropologists by applying theirknowledge of anatomy andanthropology to reconstructthe flesh and bones of extincthumans, such as theNeanderthals.

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Critical Thinking/ProblemSolving, p. 16

Reteaching Skills Trans-parency 25 and Master

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ago. However, some scientists pro-pose that more human-lookinghominids might have arisen from H. erectus before it disappeared.

Culture developed in modern humans

The incomplete fossil record andthe inaccuracies of dating fossils pro-duce controversy about dating theemergence of modern humans.However, paleoanthropologists haveenough evidence to propose possiblepaths to the origin of the modernhuman species, Homo sapiens. Adescription of one such path follows.

The fossil record indicates that thespecies H. sapiens appeared in Europe,Africa, the Middle East, and Asiaabout 100 000 to 400 000 years ago.The early forms of the species arecalled archaic H. sapiens because theirskulls resemble those of H. erectus buthave less prominent browridges,more bulging foreheads, and smallerteeth. Also, the braincases of archaicH. sapiens are larger than those of H. erectus, and can contain a brainvolume of 1000 to 1400 cm3, which iswithin the modern human range.

Best known among these archaicH. sapiens were Neanderthals (nee AN

dur tawlz), illustrated in Figure 16.12.

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Figure 16.12Neanderthals wereskilled hunters. Theyhad many tools,including spears,scrapers, and knives.

You can compare the sizes of twoskulls of the genus Homo in theProblem-Solving Lab on this page.

The Neanderthals lived fromabout 35 000 to 100 000 years ago inEurope, Asia, and the Middle East.

How similar are Neanderthals and humans? Fossil evidence can provide clues to similarities and differences between Neanderthals and humans.

AnalysisExamine the diagram of a

human skull superimposed on a Neanderthal skull. The cranial capacities (brain size) of the two skulls are provided.

Thinking Critically1. How much larger is a Neanderthal brain than a human

brain? Express the value as a percentage.2. Which skull has the more protruding jaw? A thicker

browridge? Are a protruding jaw and thick browridgesmore apelike or humanlike characteristics? Explain yourjudgment.

3. What clues do fossils such as spear points and hand axes,shelters made of animal skins, and flowers and animalhorns at burial sites provide about the lifestyle ofNeanderthals?

Problem-Solving Lab 16-2Problem-Solving Lab 16-2 Applying Concepts

AA

Brow-ridge

1600 cm3

1450 cm3

Neanderthal

Modern human

DECODE

Purpose Students will compare Nean-derthals and modern humans.

Process Skillsthink critically, apply concepts,compare and contrast, draw aconclusion, interpret scientificillustrations, observe and infer

Teaching Strategies■ Review percentage.■ Illustrate brain volume usingtwo beakers filled respectivelywith 1600 mL and 1450 mL ofcolored water. A cm3 and mL arecomparable

Thinking Critically

1. 150 cm3 larger—9.4 % larger2. Neanderthal has the apelike

features of a thick brow ridgeand a protruding jaw.

3. They were probably huntersand had religious values.

Performance Ask studentsto redraw the outlines of bothskulls and reconstruct the appear-ance of both heads by drawing thelocations of skin and muscle. Usethe Performance Task AssessmentList for Scientific Drawing inPASC, p. 55.

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Analysis1. What is the average height of your

class members? The average forearmlength? The average finger length?Answers depend on measurements.

2. Explain the variations. Traits andgrowth rates vary among humans.

3. How might the data change if youmeasured the same traits of a group ofadults? fewer extreme measurements

Skill Have students develop hypo-theses about how natural selection mayact on the variability of these three traitsin the future. Use the Performance TaskAssessment List for Formulating aHypothesis in PASC, p. 21. L2

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You can see a Homo habilis skull inFigure 16.10.

Hunting and using fireSome anthropologists propose that

a H. habilis population gave rise toanother species about 1.6 millionyears ago. This new hominid specieswas called Homo erectus, which means“upright human.” H. erectus had alarger brain and a more humanlike facethan H. habilis. However, it had promi-nent browridges and a lower jaw with-out a chin, as shown in Figure 16.11,which are apelike characteristics.

Some scientists interpret the stonetools called hand axes that they findat some H. erectus excavation sites asan indication that H. erectus hunted.In caves at these sites, they have alsofound hearths with charred bones.This evidence suggests that thesehominids used fire and lived in caves.

The distribution of fossils indicatesthat H. erectus migrated from Africaabout 1 million years ago. Then thishominid spread through Africa andAsia, and possibly migrated intoEurope, before becoming extinctbetween 300 000 and 500 000 years


Figure 16.11An almost com-plete Homo erec-tus skeleton of a12-year-old malewas discoveredin East Africa in1985. H. erectushad a brain vol-ume of about900 cm3 and longlegs like modernhumans.

Figure 16.10The average brain volume of Homo habiliswas 600 to 700 cm3,smaller than the aver-age 1350 cm3 volume of modern humans, but larger than the 400 to 500 cm3 volumeof australopithecines.

Alternative LabMeasuring Human Variation

Purpose Students will analyze variations in threehuman traits.Materialsmetric ruler or tape measure

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1. Prepare a data table with the follow-ing headings: Height (cm), Length ofleft index finger (cm), and Length ofleft forearm (cm).

2. Working with a partner, measure incentimeters your height, the length ofyour left index finger, and length ofyour left forearm (elbow to wrist).Record the results in your data table

and on a class data table. Calculate aclass average for each measurement.

3. Divide the class measurements for eachtrait into five equal intervals. Countthe number of students within eachinterval. Make bar graphs for eachmeasurement.

Expected ResultsThe data will vary. Students will note awide range of variation in each trait.

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Skill Modern primateswith large molars eat tough foodssuch as plant stems, seeds, andfruits. Living gorillas have anaverage molar area of 1011 mm2

and humans average 500 mm2. A.africanus had an average molararea of 901 mm2 and H. erectusaveraged 656 mm2. Have studentsuse the data to infer the diets ofA. africanus and H. erectus.P

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Doing Field WorkAsk students to imagine thatthey are studying evidence ofHomo erectus in a cave. Havethem make a list of evidence-gathering rules that includeways of protecting the siteand assuring accurate mea-surements, map-making, andinformation recording in adatabase.

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Problem-Solving Lab 16-2Problem-Solving Lab 16-2

VIDEODISCThe Infinite Voyage: TheDawn of Humankind

Evolution of Early Man (Ch. 2)6 min.

Cave Art: Religious and CulturalSignificance (Ch. 1)

6 min. 30 sec.

!77BB"

!7-8J" VIDEODISCThe Infinite Voyage: TheDawn of Humankind

Development of Modern Man (Ch. 4), 10 min.

!7KVF"

Fossil evidence shows that humanshave not changed much anatomicallyover the last 200 000 years. Humansprobably first established themselvesin Africa, Europe, and Asia. Then,about 12 000 years ago, evidenceshows that they crossed a land bridge

Figure 16.14These diagrams rep-resent two possiblepathways for theevolution of Homosapiens.

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Pathway 1

Mill

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Australopithecus afarensis

Australopithecus africanus

Homo habilis

A. boiseri A. robustus

Homo erectus

Homo sapiens

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Australopithecus afarensis

Australopithecus africanus

A. aethiopicus

Homo habilis

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Homo erectus

Homo sapiens

Section AssessmentSection Assessment

Understanding Main Ideas1. What evidence supports the idea that species of

australopithecines were intermediate formsbetween apes and humans?

2. Why was the development of bipedalism a veryimportant event in the evolution of hominids?

3. What evidence supports the idea that H. habiliswas an ancestor of H. erectus?

4. Describe the evidence that supports the idea that Neanderthals were not the ancestors of Cro-Magnon people?

Thinking Critically5. What kind of animal bones might you expect to

find at the site of Homo habilis remains if H.habilis was a scavenger? A hunter?

6. Interpreting Scientific Illustrations Draw a time line to show the evolution of hominids.Indicate each species of hominid that evolvedand where it evolved. For more help, refer toThinking Critically in the Skill Handbook.

SKILL REVIEWSKILL REVIEW


into North America. You can readmore abouth this event in the EarthScience Connection at the end of thechapter. By 8000 to 10 000 years ago,Native Americans had built perma-nent settlements and were domesti-cating animals and farming.

445

3 AssessCheck for Understanding

Visual-Spatial Have studentsconstruct a time line of the

following events; use of fire,bipedal movement, tool use, lan-guage, art, burial of the dead.

ReteachVisual-Spatial Have studentsmake a bar graph showing

the evolution of human brainsize.

ExtensionHave students illustrate a humanphylogenetic tree.

Performance Have stu-dents give an oral report about a day in the life of a hominidspecies.

4 CloseDiscussionDiscuss what future paleoanthro-pologists might determine abouttoday’s humans. Have studentsidentify probable artifacts andtheir information. L1

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Section AssessmentSection AssessmentSection Assessment1. They have a brain capacity larger than

apes and smaller than humans. Theyclimbed trees like apes, but walked likehumans.

2. Bipedalism allowed hominids to betterscan the horizon for predators and freedtheir forelimbs for carrying objects.

3. Homo habilis was the first hominid topurposefully construct stone tools.

4. Genetic and archaeological evidence sug-gests that Neanderthals were not theancestors of Cro-Magnon people.

5. If H. habilis were scavengers, bones thatcontain little meat, such as ribs, would beat their sites. If they were hunters, therewould be meat-containing bones at theirsites.

6. Evaluate the time lines for accuracy.

Fossils reveal that Neanderthals hadthick bones and large faces withprominent noses. The brains ofNeanderthals were at least as large asthose of modern humans.

The fossil records also indicatethat Neanderthals lived in caves dur-ing the ice ages of their time. In addi-tion, the tools, figurines, flowers, andother evidence from excavation sites,such as burial grounds, suggest thatNeanderthals may have had religiousviews and communicated throughspoken language.

What happened to Neanderthals?Could Neanderthals have evolved

into modern humans? The fossilrecord shows that a more moderntype of H. sapiens spread throughoutEurope between 35 000 to 40 000years ago. This type of H. sapiens iscalled Cro-Magnon (kroh MAG nun).Cro-Magnons were identical tomodern humans in height, skullstructure, tooth structure, and brain size. Paleoanthropologists suggest that Cro-Magnons were

toolmakers and artists, as shown inFigure 16.13. Cro-Magnons proba-bly also used language, as their skullscontain a bulge that corresponds tothe area of the brain that is involvedin speech in modern humans.

Did Neanderthals evolve into Cro-Magnons? Current genetic andarchaeological evidence indicates thatthis is unlikely. Current dates forhominid fossils suggest that modernH. sapiens appeared in both SouthAfrica and the Middle East about 100 000 years ago, which was aboutthe same time the Neanderthalsappeared. In addition, genetic evi-dence supports the idea of an Africanorigin of modern H. sapiens, perhapsas early as 200 000 years ago. Thisidea suggests that the African H. sapiens migrated to Europe and Asia.

Most fossil evidence supports theidea that Neanderthals were mostlikely a side branch of H. sapiens, andnot an ancestral branch of modernhumans. Look at Figure 16.14 to seetwo proposed evolutionary paths tomodern humans.


Figure 16.13The dwelling sites ofCro-Magnons, full ofcave paintings,detailed stone andbone artifacts, andtools, have beenexcavated in Europe.

444


English Language LearnersLinguistic Have students supply thehominid species name for each of

the following descriptions: (1) earliestmaker of stone tools, (2) chimpanzee-sized brain and bipedal, (3) earliesthominid to move out of Africa, (4) thick-boned and maker of diverse tools.P

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P R O J E C TSocial Behavior in EarlyHominids

Interpersonal Have small groups ofstudents develop a project for study-

ing nonhuman primates to infer socialbehavior in early hominids.

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VIDEODISCThe Secret of LifeHomo sapiens—

Origin (a)

The Infinite Voyage: The Dawnof Humankind, Bridging ofFossils and Genetic Research (Ch. 9), 2 min. 30 sec.

!7;FjH"

!7;FtI"

!7~$G"Evolution of the Mind (Ch. 10)4 min.

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Visual LearningFigure 16.14 illustrates two pos-sible phylogenetic trees of humanevolution. Point out that somepaleoanthropologists have sug-gested alternative phylogenies.

EnrichmentVisual-Spatial Have studentsdraw probable evolutionary

pathways of humans that includetime periods and three character-istics of each species. L3

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VIDEODISCThe Infinite Voyage:The Dawn of Human-

kind, “Out-of-Africa” vs. Multi-regional Debate on Originationof Modern Man (Ch. 8)6 min.

!7s~D"


Basic Concepts Transparency23 and Master

Reinforcement and StudyGuide, pp. 71-72

Content Mastery, pp. 77, 79-80 L1

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Homo sapiens—Origin (b)


1. Comparing and Contrasting Howwould you describe the similari-ties and differences in face-to-brain area in the three primates?

2. Interpreting Observations Howdo the cranial capacities compareamong the three skulls? How dothe jaw angles compare?

3. Drawing Conclusions Based onyour findings, what statementscan you make about the place-ment of australopithecines inhuman evolution?

ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

1. Your teacher will provide copiesof the skulls (1/2 natural size) ofAustralopithecus africanus, Gorillagorilla, and Homo sapiens.

2. The rectangles drawn over theskulls represent the areas of thebrain (upper rectangle) and face(lower rectangle). On each skull,determine and record the area ofeach rectangle (length � width).

3. Measure the diameters of the cir-

PROCEDUREPROCEDURE

1. Face area in cm2

2. Brain area in cm2

3. Is brain area smalleror larger than face area?

4. Is brain area 3 times larger than face area?

5. Cranial capacity in cm3

6. Jaw angle

7. Does lower jaw stick outin front of nose?

8. Is sagittal crest present?

9. Is browridge present?

Gorilla Australopithecus Modern human

Data Table

cles in each skull. Multiply thesenumbers by 200 cm2. The resultis the cranial capacity (brain vol-ume) in cubic centimeters.

4. The two heavy lines projected onthe skulls are used to measure howfar forward the jaw protrudes.Use your protractor to measurethe outside angle (toward theright) formed by the two lines.

5. Complete the data table.

Going FurtherGoing Further

Application Different parts of the australopithecine skeleton are also interme-diate between apes and humans. Obtaindiagrams of primate skeletons to determinethe similarities and differences.

To find out more aboutprimate evolution, visit

the Glencoe Science Web Site.www.glencoe.com/sec/science


2. Apes have a small cranialcapacity, whereas humanshave a large cranial capacity,and that of australopithecineswas intermediate but closerto the apes. An ape has asmall jaw angle, and a humanhas a large jaw angle. The jawangle of australopithecineswas intermediate but closerto that of the ape.

3. Many australopithecine skulltraits were intermediatebetween those of apes andhumans, and some were moresimilar to those of apes.Australopithecines representvery early human ancestors.

Portfolio Have studentsformulate three hypotheses aboutthe natural selection pressuresthat may have taken place duringaustralopithecine evolution. Havethem place their hypotheses intheir portfolios. Use the Perform-ance Task Assessment List forFormulating a Hypothesis inPASC, p. 21. PP

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447


Comparing Skullsof Three Primates

A ustralopithecines are the earliest hominids in the fossil record. Inmany ways, their anatomy is intermediate between living apes

and humans. In this lab, you’ll determine the apelike and humanlikecharacteristics of an australopithecine skull, and compare the skulls ofaustralopithecines, gorillas, and modern humans. The diagrams of skullsshown below are one-fourth natural size. The heavy black lines indicatethe angle of the jaw.


ProblemHow do skulls of primates provide

evidence for human evolution?

ObjectivesIn this BioLab, you will:■ Determine how paleoanthropolo-

gists study early human ancestors.■ Compare and contrast the skulls of

australopithecines, gorillas, andmodern humans.

Materialsmetric rulerprotractorcopy of skull diagrams

Skill HandbookUse the Skill Handbook if you need

additional help with this lab.

PREPARATIONPREPARATION

Gorilla1/4 natural size

Modern human1/4 natural size

Australopithecus1/4 natural size

Browridge

Sagittal crest

Browridge


Time Allotment One class period

Process Skillsobserve and infer, measure in SI,hypothesize, compare and con-trast, make and use tables

■ Give each student a copy ofthe skull diagrams from theBioLab and MiniLab Work-sheets book to use in thisBioLab. These skulls are one-half natural size.

■ Alternatively, copy the skull arton this student edition pageand increase it by 50% for stu-dents to use.

1. Humans have a small facialarea compared with brainarea. Apes have a large facialarea compared with brainarea. Australopithecines wereintermediate between apesand humans but closer toapes.

ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

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PROCEDUREPROCEDURE

Teaching Strategies■ Remind students that australopithecinesexisted between 1 and 5 million years ago,around the time that African apes andhumans probably diverged. Because of theirage, australopithecines were probably primi-tive anatomically.■ To estimate cranial capacities, studentsshould draw circles just inside each skull on

the worksheets provided or on the copiedand enlarged skulls from the student editionpage.■ Estimating cranial capacity by multiply-ing by the factor of 200 is suitable only forthese drawings because the factor is basedon the scale of the drawings at one-half nat-ural size.

Going FurtherGoing Further

Logical-MathematicalObtain illustrations or ac-

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1. Face area in cm2

2. Brain area in cm2

3. Is brain area smaller or larger than face area?

4. Is brain area 3 times larger than face area?

5. Cranial capacity in cm3

6. Jaw angle

7. Does lower jaw stick out in front of nose?

8. Is sagittal crest present?

9. Is browridge present?

32 cm2

23 cm2

SmallerNo600 cm3

35°YesYesYes

19 cm2

23 cm2

LargerNo600 cm3

55°YesYesYes

12 cm2

40 cm2

LargerYes1060 cm3

90°No NoNo

Gorilla Australopithecus Modern human

Data Table


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Chapter 16 AssessmentChapter 16 Assessment

SUMMARYSUMMARY

Section 16.1

Section 16.2

Main Ideas■ Primates are primarily an arboreal group of

mammals. They have adaptations, such asbinocular vision, opposable thumbs, and flexiblejoints, that help them survive in trees.

■ There are two groups of primates: prosimians,such as lemurs and tarsiers; and anthropoids,which include monkeys and hominoids.

■ Fossils indicate that primates appeared on Earthabout 65 to 70 million years ago. Major trendsin primate evolution include an increasing brainsize and walking upright.

Vocabularyanthropoid (p. 432)opposable thumb

(p. 431)prehensile tail (p. 433)primate (p. 429)

PrimateAdaptation andEvolution

Main Ideas■ One idea about the evolution of humans is that

the earliest hominids arose in Africa approxi-mately 5 to 8 million years ago. Australopithe-cine fossils indicate that these individuals werebipedal, but also climbed trees.

■ The fossil record indicates that humans devel-oped over time. Their brain and body size grad-ually increased, bipedalism became more effi-cient, and their jaws and teeth decreased in size.

■ The appearance of stone tools in the fossilrecord coincided with the appearance of thegenus Homo about 2 million years ago. The useof fire and language, as well as the developmentof culture, probably developed in more recentHomo species.

Vocabularyaustralopithecine

(p. 440)bipedal (p. 438)Cro-Magnon (p. 444)hominid (p. 438)Neanderthal (p. 443)

HumanAncestry

CHAPTER 16 ASSESSMENT 449

1. Which living primate group is probably themost similar to the earliest primates?a. apes c. prosimiansb. monkeys d. hominids

2. The first Homo sapiens were ________.a. Cro-Magnon peopleb. Homo erectusc. Australopithecus afarensisd. Neanderthals

UNDERSTANDING MAIN IDEASUNDERSTANDING MAIN IDEAS 3. Which of the following pairs of terms is mostclosely related?a. primate—squirrelb. arboreal—gorillac. prosimian—hominidd. Cro-Magnon—Homo sapiens

4. Because the eyes of primates face forward,they ________.a. have color visionb. have binocular visionc. can climb trees welld. see well to the sides

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Main IdeasSummary statements can be used bystudents to review the major con-cepts of the chapter.

Using the VocabularyTo reinforce chapter vocabulary, usethe Content Mastery Booklet andthe activities in the Interactive Tutorfor Biology: The Dynamics of Life onthe Glencoe Science Web Site:www.glencoe.com/sec/science


All ChapterAssessment

questions and answers have beenvalidated for accuracy and suitabil-ity by The Princeton Review.

The Bering Land Bridge, or Beringia, is a stripof land that connects Asia and North America.During the last Ice Age, Beringia was dry land

above sea level. Human ancestors may havewalked across this land to reach North America.

The 1500 km-wide piece of land known as theBering Land Bridge is located between the

Bering and Chukchi Seas and links northeasternSiberia and northwestern North America. Today,the land bridge is about 267 meters below theocean’s surface. However, during the last ice age,sea level was much lower than it is today. At thattime, this land bridge was above the water’s sur-face. Humans could have migrated from Asia toNorth America across this land bridge. Recentevidence indicates that such a human migrationprobably occurred 11 330 to 11 000 years ago.

Dating the land bridge Anthropologists compared two kinds of data to determine the 11 000-year date for human migration acrossBeringia. They used radiometric dating methodson fossils and data tables that indicate the sealevels at different times in geological history.Both data reveal that Beringia was last above sea level about 11 000 years ago, which is about 4000 years earlier than previous calculations haddetermined.

Pollen reveals plant life Pollen found in sediments dredged from the bottoms of theBering and Chukchi Seas indicates that the landbridge and the surrounding areas were tundraecosystems. Willows, birch, sedge tussocks, and spring flowers were the dominant plants of the area, and caribou probably roamed overthe frozen soil.

The pollen studies also showed that the temperature at the time was warmer than it is inpresent-day Alaska. Scientists have used thisfinding to propose that perhaps the Ice Age was


ConnectionEarth ScienceEarth Science

Connection The Land Bridge tothe New World

Study the map shown above. Suggest anotherway that prehistoric humans might have enteredthe New World.

To find out more about humanorigins, visit the Glencoe Science

Web Site.www.glencoe.com/sec/science

CONNECTION TO BIOLOGYCONNECTION TO BIOLOGY

ending. The glaciers would have melted in awarming climate and the sea level would haverisen, covering the land bridge with water.

An alternate route In addition to these findings, recent archeological studies in SouthAmerica have uncovered new information about human migration to the New World.Researchers from the University of Illinois havediscovered evidence that prehistoric humanslived in Brazil about 12 800 years ago. The question paleoanthropologists now ask is didhumans enter the New World only via theBering Land Bridge, or was there another route to the Americas?

Modern coastline

Ancient coastline

Ice sheets 21 000 years ago

Ice sheets 12 000 years ago

Possible migration route

NORTHAMERICA

SOUTHAMERICA

Siberia

448

PurposeStudents will learn about thetypes of evidence that paleoan-thropologists use to propose howmodern humans entered the NewWorld.

Teaching Strategies■ Use the illustration on thispage, along with a world map orglobe, to discuss how humanancestors might have migratedfrom their African place of originto the Americas.■ Review radiometric dating.■ Students can prepare wetmounts of pollen from a varietyof flowers and, after viewing,draw and label each pollen type.■ Ask students to imagine thatthey are in the first group ofhumans crossing the Bering LandBridge. Have them write an essayabout their experiences.

Connection to BiologyPrehistoric humans may haveused boats to enter the NewWorld.

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ConnectionEarth ScienceEarth Science

Connection

1. c2. d3. d4. b

UNDERSTANDING MAIN IDEASUNDERSTANDING MAIN IDEAS

Internet Address Book

Note Internet addresses that you find useful in the spacebelow for quick reference.


Chapter Assessment, pp. 91-96MindJogger VideoquizzesComputer Test BankBDOL Interactive CD-ROM, Chapter

16 quiz

VIDEOTAPEMindJogger Videoquizzes

Chapter 16: Primate EvolutionHave students work in groups as they playthe videoquiz game to review key chapterconcepts.



For additional review, use the assessmentoptions for this chapter found on the Biology: TheDynamics of Life Interactive CD-ROM and on theGlencoe Science Web Site.www.glencoe.com/sec/science

CD-ROM


CHAPTER 16 ASSESSMENT 451

25. Observing and Inferring How could you tellfrom the position of the foramen magnumthat an animal walked upright? Explain.

26. Formulating Hypotheses How would youtest the idea that opposable thumbs are bene-ficial adaptations for arboreal mammals?

27. Interpreting Data The data in Table 16.2are from an experiment comparing aminoacid sequences in apes. What conclusions canyou draw from such data?

28. Concept Mapping Complete the conceptmap by using the following vocabulary terms:australopithecine, hominids, Cro-Magnon,bipedal, Neanderthal, opposable thumbs

THINKING CRITICALLYTHINKING CRITICALLY ASSESSING KNOWLEDGE & SKILLSASSESSING KNOWLEDGE & SKILLS

The intermembral index is the ratio of forelimb length to hindlimb length.Primates with a high index are good branchswingers. Primates with a low index tend towalk on all four legs.

Interpreting Data Study Table 16.3 andanswer the following questions.1. Which group appears to have the great-

est range of intermembral distance?a. prosimiansb. New World monkeysc. Old World monkeysd. hominoids

2. Which group appears to have the nar-rowest range of intermembral distance?a. prosimiansb. New World monkeysc. Old World monkeysd. hominoids

3. Interpreting Data To which groupmight a primate with an intermembralindex of 92 belong? Explain your answer.

Species

Intermembral IndexFORELIMB LENGTH HINDLIMB LENGTH X 100

Prosimians

Indri

Slow Ioris

New World monkeys

Squirrel monkey

Black spider monkey

Old World monkey

Pig-tailed macaque

Hanuman langur

Hominoids

Orangutan

Common chimpanzee

Table 16.3 Intermembral Index of Some Primates

64

88

80

105

92

83

139

103

Primate

Percentage amino acidsequence difference from humans

Gibbon

Orangutan

Chimpanzee

Gorilla

Table 16.2 Comparisons of Amino Acid Sequences

5.2

3.7

1.8

2.1

thrivedin the

Ice Age

include

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25. For an animal to walk erect, itsspinal cord must enter the skullat its base. The foramen mag-num would be located moretoward the back of the skullthan at its base in an animalthat used four appendages forlocomotion.

26. Students can design an experi-ment to test and compare thesuccess of two arboreal animals,a primate and a nonprimate, ina situation unique to arboreallife, such as obtaining fruit atthe ends of branches.

27. Chimpanzees are the mostclosely related to humans, thengorillas, then orangutans, andfinally gibbons.

28. 1. Hominids; 2. Bipedal; 3. Opp-osable thumbs; 4. Australo-pithecine; 5. Neanderthal; 6. Cro-Magnon

THINKING CRITICALLYTHINKING CRITICALLY


1. d2. c3. An intermembral index of

92 could place this newprimate with Old Worldmonkeys. It could alsoplace the primate withNew World monkeys as 92is in the range shown.More information wouldbe needed to correctlyplace this new primate.


5. Primates native to the area indicated by themap below are ________.a. Old World monkeys c. apesb. New World monkeys d. prosimians

6. The science of studying the fossils of humansis ________.a. paleoanthropology c. paleontologyb. geology d. anthropology

7. The dominant sense in primates is ________.a. vision c. smellb. taste d. hearing

8. Which of these is NOT a primate?a. human c. lemurb. squirrel d. orangutan

9. The earliest primates were most like________.a. c.

b. d.

10. The study of the fossil Lucy helped scientistsdetermine that ________.a. both primates and hominids have color

visionb. hominids are primates with opposable

thumbsc. hominids had large brains before they

walked uprightd. hominids walked upright before they had

large brains11. Organisms that walk upright on two legs are

________.12. The term used to describe the tails of New

World monkeys is ________.13. An early group of humans who may have

been the first to develop religious views and aspoken language were ________.

14. The fossil of the Taung child represents thefirst ________ skull ever discovered.

15. A group of mammals that includes lemurs,monkeys, apes, and humans is ________.

16. Humanlike hominids are grouped in thegenus ________.

17. Toolmakers and artists who lived in Europeabout 30 000 years ago were the ________.

18. ________ enables primates to perceive depthand thereby gauge distances.

19. The primate structure that allows for thegrasping of objects is ________.

20. African hominids who possessed apelike andhumanlike qualities are classified as ________.

21. Suppose that you were told that a scientistfound a 25 000-year-old arrowhead in Arizona.Would you be surprised? Why or why not?

22. Why is it important for a paleoanthropolo-gist to know about all primates?

23. Some scientists suggest that Neanderthalsevolved into modern humans. What informa-tion should they gather to support their idea?

24. How is the evolution of apes an example ofadaptive radiation?

APPLYING MAIN IDEASAPPLYING MAIN IDEAS

450 CHAPTER 16 ASSESSMENT

TEST–TAKING TIPTEST–TAKING TIP

Dress ComfortablyLoose, layered clothing is best. Whatever the tem-perature, you’re prepared. Important test scoresdo not take climate into consideration.

P A C I F I CO C E A N

AT L A N T I CO C E A N

450

5. b6. a7. a8. b9. b

10. d11. bipedal12. prehensile13. Neanderthals14. australopithecine15. primates16. Homo17. Cro-Magnon humans18. binocular vision19. opposable thumb20. australopithecines

21. Yes. The first evidence of hu-mans in the Americas datesfrom about 12 000 years ago. A25 000-year-old arrowheadwould more than double thetime that humans are known tobe in North America.

22. The adaptations that evolved innonhuman primates laid thegroundwork for adaptationsthat arose during hominid evo-lution.

23. Answers could include that sci-entists might compare the DNAof modern humans and that ofNeanderthals, if such DNAexists. Or scientists could com-pare the skulls or skeletons ofNeanderthals and modernhumans.

24. Apes evolved their unique traitsas a result of adapting to condi-tions in the environments theyinhabited.

APPLYING MAIN IDEASAPPLYING MAIN IDEAS



chapter 16: primate evolution · the main theme of this chapter is evolution. students learn how...

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