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5 Primate EvolutionCHAPTER OUTLINE

OVERVIEW

THE FOSSIL RECORD

DATING THE PAST

Relative Dating

Absolute Dating

EARLY PRIMATES

Early Cenozoic Primates

Oligocene Anthropoids

MIOCENE HOMINOIDS

Proconsul

Afropithecus andKenyapithecus

Sivapithecus

Gigantopithecus

Dryopithecus

Oreopithecus

Beyond the Classroom:Maceration of aCanadian Lynx

A MISSING LINK?

NYTIMES.COM NEWS BRIEFS

Tiny Fossil Animal May Link By John Noble WilfordLower Primates with Humans March 16, 2000

Fossil bones of an animal no bigger than a shrew and weighing less than

an ounce have been identified as belonging to the earliest known relative

in the primate lineage that led to monkeys, apes and humans. The wee

animal lived 45 million years ago in a humid rain forest in what is now

China. It was probably nocturnal and solitary,

and fed on insects and fruit. If not careful in its

usual place up in the trees, this primate often

wound up as an owl’s midnight feast. In fact,

some of the bones in question may well have

been regurgitated by an owl after one such

repast.

The paleontologists

who announced the dis-

covery yesterday said the

fossil animals, named

Eosimias for “dawn mon-

key,” were the best evi-

dence yet for fixing the

time and place of one of

the more fateful branch-

ings in evolution. Eosimias

appeared to be a transi-

tional figure when lower

primates, known as pro-

simians, went their sepa-

rate way, developing into today’s lemurs, lorises,

bush babies and tarsiers, while the diverging

higher primates, anthropoids, evolved into more

prepossessing creatures, eventually including

human beings.

“We have the first unambiguous evidence

that is able to bridge the anatomical gap

between lower and higher primates,” said Dr.

Daniel L. Gebo, a paleontologist at Northern Illi-

nois University in DeKalb who was a member of

the discovery team.

A close examination of the tiny ankle and

foot bones, some the size of grains of rice,

established that Eosimias is an extremely primi-

tive member of the anthropoid lineage, Dr.

Gebo and other scientists said. The shapes of

the bones and structure of joints showed that

this fossil species was able to walk on all four

limbs on the tops of branches, much like living

monkeys.

The lower primates are not built to be

quadrupedal walkers. They cling to trees and leap

from one to another. As anatomists can readily

see, the heel bones of prosimians are longer than

those of anthropoids, giving them leverage for

their long leaps. All primates, whether lower or

higher, are distinguished from other mammals by

their larger brains, grasp-

ing hands and feet, nails

instead of claws and eyes

in the front of the skull . . .

The minute size and

other primitive character-

istics, Dr. Gebo said,

“probably means we’re

getting close to the tran-

sition between higher

and lower primates.”

This was further evi-

dence that, although the

more immediate human

forebears arose in Africa, their earliest primate

ancestors appeared to come from Asia. Some-

how primates then migrated to Africa . . .

Working at two sites, one a quarry 100 miles

west of Shanghai and the other in Shanxi

province along the Yellow River in central China,

the American-Chinese expedition was unable to

find any complete skeletons, but it found as

many as 50 foot bones and many other lower

limb bones . . .

“The most interesting aspect of these new

foot bones is that they represent a mosaic,” Dr.

Gebo said in a statement issued by his university.

“They possess primitive lower-primate features

as well as several advanced or higher-primate

characteristics.” No other fossil primate at such

an early time, he added, “has this interesting

combination.”

Source: http://www.nytimes.com/library/national/science/031600sci-animal-fossil.htm.

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overview The primateorder evolved by exploiting new opportunitiesthat arose at the end of the Mesozoic era. Theage of reptiles yielded to the age of mam-mals—the Cenozoic era, which began some 65million years ago. Flowering plants prolifer-ated, along with the insects attracted to themand the animals that preyed on those insects.Primate traits like grasping hands and depthperception aided in the capture of insects andwere adaptive in an arboreal environment.

By the Eocene epoch, primates hadspread and diversified, mainly in Europe andNorth America, which were connected at thattime. Among primates, the Eocene was theage of prosimians. By the end of the Eocene,the anthropoids had emerged; they eventuallydisplaced the prosimians in most places. In thenext epoch, the Oligocene, the New Worldmonkeys split off from the catarrhines, theancestors of Old World monkeys, apes, andhumans.

The ensuing Miocene epoch, divided intoEarly, Middle, and Late, witnessed a fluores-cence of proto-apes, an amazing variety unlikeanything that survives in the contemporaryworld. Some 16 million years ago, Africa col-lided with Eurasia. The new land connectionallowed African fauna, including apes, tospread into Europe and Asia, where the apesproliferated. The lines leading to the orang-utan, on the one hand, and the African apes,on the other, split during the middle Miocene.The common ancestor of humans, chimps, andgorillas—as yet unidentified—lived during thelate Miocene, some five to eight million yearsago.

The Fossil Record

The fossil record is not a representative sample ofall the species that have lived on earth. Somespecies and body parts are better representedthan others are, for a variety of reasons. Hardparts, like bones and teeth, preserve better thansoft parts, like flesh and skin. The chances of fos-silization increase when remains are buried in anewly forming sediment, such as silt, gravel, orsand. Good places for bones to be buried in sedi-ments include swamps, flood plains, river deltas,lakes, and caves. The species that inhabit suchareas have a better chance to be preserved thando animals that live in other habitats. Fossiliza-tion is also favored in areas with volcanic ash, orwhere rock fragments eroding from rising high-lands are accumulating in valleys or lake basins.Once remains do get buried, chemical conditionsalso must be right for fossilization to occur. If thesediment is too acidic, even bone and teeth willdissolve. The study of the processes that affectthe remains of dead animals is called taphonomy,from the greek taphos, which means “tomb.” Suchprocesses include scattering by carnivores andscavengers, distortion by various forces, and thepossible fossilization of the remains.

Fossils comprise a very small sample of all theanimals that have ever lived. This sample isbiased, with some areas and times much betterrepresented than others are. Conditions favoringfossilization open special “time windows” forcertain places and times, like western Kenyafrom 18 to 14 m.y.a.—million years ago. Becausewestern Kenya was geologically active then, ithas a substantial fossil record. Between 12 and 8m.y.a., the area was quieter geologically, andthere are few fossils. After 8 m.y.a., another timewindow opens in the Rift Valley area of easternKenya. The East African highlands were rising,volcanoes were active, and lake basins wereforming and filling with sediments. This timewindow extends through the present andincludes many hominid fossils. Compared withEast Africa, West Africa has been more stablegeologically and has few time windows (Jollyand White 1995).

The conditions under which fossils are foundalso influence the fossil record. For example, fos-sils are more likely to be uncovered through ero-

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Relative DatingChronology is established by assigning dates togeologic layers (strata) and to the material remains,such as fossils and artifacts, within them. Datingmay be relative or absolute. Relative dating estab-lishes a time frame in relation to other strata ormaterials, rather than absolute dates in numbers.Many dating methods are based on the geologicalstudy of stratigraphy, the science that examinesthe ways in which earth sediments accumulate inlayers known as strata (singular, stratum). In anundisturbed sequence of strata, age increases withdepth. Soil that erodes from a hillside into a valleycovers, and is younger than, the soil depositedthere previously. Stratigraphy permits relativedating. That is, the fossils in a given stratum areyounger than those in the layers below and olderthan those in the layers above. We may not knowthe exact or absolute dates of the fossils, but wecan place them in time relative to remains in otherlayers. Changing environmental forces, such aslava flows or the alternation of land and sea, causedifferent materials to be deposited in a givensequence of strata, which allows scientists to dis-tinguish between the strata.

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sion in arid areas than in wetareas. Sparse vegetation allowswind to scour the landscape and touncover fossils. The fossil recordhas been accumulating longer andis more extensive in Europe thanin Africa because civil engineeringprojects and fossil hunting havebeen going on longer in Europethan in Africa. A world map show-ing where fossils have been founddoes not indicate the true range ofancient animals. Such a map tellsus more about ancient geologicalactivity, modern erosion, or recenthuman activity such as paleonto-logical research or road building.In considering the primate fossilrecord, we’ll see that different areas provide moreabundant fossil evidence for different time peri-ods. This doesn’t necessarily mean that primateswere not living elsewhere at the same time. Forhominid fossils, for example, the fact that most ofthe earliest ones come from eastern Africa doesnot necessarily mean that comparable hominidsdid not also live in southern Africa then.

The discussions of primate and human evolu-tion therefore must be tentative because the fossilrecord “is woefully limited and spotty. That iswhy each significant find sets off a new spate ofspeculations—and often a new barrage of attackson some previously dug and stoutly heldtrenches” (Fisher 1988a, p. 23). Much is subject tochange as knowledge increases. Before consider-ing our fossil ancestors, however, we need toreview some techniques used to establish whenthey lived.

Dating the Past

Paleontology is the study of ancient life throughthe fossil record, and paleoanthropology is thestudy of ancient humans and their immediateancestors. These fields have established a timeframe, or chronology, for the evolution of life,including primates and humans. Scientists useseveral techniques to date fossils. These methodsoffer different degrees of precision and areapplicable to different periods of the past.

A swamp is a good place for bones to be buried insediments. Here a female mammoth is representedsinking into the La Brea Tarpits in Los Angeles,California. What other locales and conditions favorfossilization?

Remains of animals and plants that lived at thesame time are found in the same stratum. Basedon fossils found in stratigraphic sequences, thehistory of vertebrate life has been divided intothree main eras. The Paleozoic was the era ofancient life—fishes, amphibians, and primitivereptiles. The Mesozoic was the era of middle life—reptiles, including the dinosaurs. The Cenozoic isthe era of recent life—birds and mammals. Eachera is divided into periods, and the periods aredivided into epochs. (See Figure 5.1.)

Anthropologists are concerned with the Ceno-zoic era, which includes two periods: Tertiary andQuaternary. Each of these periods is subdividedinto epochs. The Tertiary had five epochs: Pale-ocene, Eocene, Oligocene, Miocene, and Pliocene.The Quaternary includes just two epochs: Pleis-tocene and Holocene, or Recent. Figure 5.1 givesthe approximate dates of these epochs. Sedimentsfrom the Paleocene epoch (65 to 54 m.y.a.) haveyielded fossil remains of diverse small mammals,some possibly ancestral to the primates. Prosimi-anlike fossils abound in strata dating from theEocene (54 to 36 m.y.a.). The first anthropoid fos-sils date to the mid- to late Eocene and earlyOligocene (36 to 23 m.y.a.). Hominoids becamewidespread during the Miocene (23 to 5 m.y.a.),and hominids first appeared in the Pliocene (5 to 2m.y.a.) (Figure 5.1).

When fossils are found within a stratigraphicsequence, scientists know their dates relative tofossils in other strata; this is relative dating.When fossils are found in a particular stratum,the associated geological features (such as frostpatterning) and remains of particular plants andanimals offer clues about the climate at the timeof deposition.

Besides stratigraphic placement, another tech-nique of relative dating is fluorine absorptionanalysis. Bones fossilizing in the same ground forthe same length of time absorb the same propor-tion of fluorine from the local groundwater. Fluo-rine analysis uncovered a famous hoax involvingthe so-called Piltdown man, once considered anunusual and perplexing human ancestor(Winslow and Meyer 1983). The Piltdown “find,”from England, turned out to be the jaw of ayoung orangutan attached to a H. sapiens skull.Fluorine analysis showed the association to befalse. The skull had much more fluorine than thejaw—impossible if they had come from the same

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Quaternary1.8 m.y.a.

Tertiary65 m.y.a.

Cretaceous146 m.y.a.

Jurassic208 m.y.a.

Triassic245 m.y.a.

Permian286 m.y.a.

Carboniferous360 m.y.a.

Devonian410 m.y.a.

Silurian440 m.y.a.

Ordovician505 m.y.a.

Cambrian544 m.y.a.

Neoproterozoic900 m.y.a.

Mesoproterozoic1,600 m.y.a.

Paleoproterozoic2,500 m.y.a.

3,800 m.y.a.

4,500 m.y.a.

The geological time scale, based on stratigraphy.Eras are subdivided into periods, and periods, into epochs. In what era, period, and epoch didHomo originate?

Figure 5.1Geological Time Scales

Era Period

Cenozoic

Mesozoic

Paleozoic

Proterozoic

Archaean

Hadean

individual and had been deposited in the sameplace at the same time. Someone had fabricatedPiltdown man in an attempt to muddle the inter-pretation of the fossil record. (The attempt waspartially successful—it did fool some scientists.)

Absolute DatingThe previous section reviewed relative datingbased on stratigraphy and fluorine absorptionanalysis. Fossils also can be dated more precisely,with dates in numbers (absolute dating), by sev-eral methods. For example, the 14C, or carbon-14,technique is used to date organic remains. This isa radiometric technique (so called because it mea-sures radioactive decay). 14C is an unstableradioactive isotope of normal carbon, 12C. Cos-mic radiation entering the earth’s atmosphereproduces 14C, and plants take in 14C as theyabsorb carbon dioxide. 14C moves up the foodchain as animals eat plants and as predators eatother animals.

With death, the absorption of 14C stops. Thisunstable isotope starts to break down into nitro-

gen (14N). It takes 5,730 years for half the 14C tochange to nitrogen; this is the half-life of 14C.After another 5,730 years only one-quarter of theoriginal 14C will remain. After yet another 5,730years only one-eighth will be left. By measuringthe proportion of 14C in organic material, scien-tists can determine a fossil’s date of death, or thedate of an ancient campfire. However, becausethe half-life of 14C is short, this dating techniqueis less dependable for specimens older than40,000 years than it is for more recent remains.

Fortunately, other radiometric dating tech-niques are available for earlier periods. One ofthe most widely used is the potassium-argon(K/A) technique. 40K is a radioactive isotope ofpotassium that breaks down into argon 40, a gas.The half-life of 40K is far longer than that of 14C1.3 billion years. With this method, the older thespecimen, the more reliable the dating. Further-more, whereas 14C dating can be done only onorganic remains, K/A dating can be used onlyfor inorganic substances: rocks and minerals.

40K in rocks gradually breaks down into argon40. That gas is trapped in the rock until the rock is

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Era Period Epoch Climate and Life Forms

Cenozoic

Quaternary

Tertiary

Holocene11,000 B.P.

Pleistocene1.8 m.y.a.

Pliocene5 m.y.a.

Miocene

23 m.y.a.

Oligocene

38 m.y.a.

Eocene

54 m.y.a.

Paleocene65 m.y.a.

Transition to agriculture; emergence of states

Climatic fluctuations, glaciation; Homo, A. boisei

A. robustus, A. africanus, A. afarensis, A. anamensis,Ardipithecus ramidus

Cooler and drier grasslands spread in middlelatitudes; Africa collides with Eurasia (16 m.y.a.);Afropithecus, Ramapithecus, Sivapithecus

Cooler and drier in the north; anthropoids in Africa(Fayum); separation of catarrhines and platyrrhines;separation of hylobatids from pongids and hominids

Warm tropical climates become widespread; modernorders of mammals appear; prosimianlike primates;anthropoids appear by late Eocene

First major mammal radiation

Figure 5.1Geological Time Scales—Concluded

Periods and Epochs of the Cenozoic Era.

intensely heated (as with volcanic activity), atwhich point it may escape. When the rock cools,the breakdown of potassium into argon resumes.Dating is done by reheating the rock and measur-ing the escaping gas.

In Africa’s Great Rift Valley, which runs downeastern Africa and in which early hominid fossilsabound, past volcanic activity permits K/A dat-ing. In studies of strata containing fossils, scien-tists find out how much argon has accumulatedin rocks since they were last heated. They thendetermine, using the standard 40K deteriorationrate, the date of that heating. Considering vol-canic rocks at the top of a stratum with fossilremains, scientists establish that the fossils areolder than, say, 1.8 million years. By dating thevolcanic rocks below the fossil remains, theydetermine that the fossils are younger than, say, 2million years. Thus the age of the fossils and ofassociated material is set at between 2 million

and 1.8 million years. Notice that absolute datingis that in name only; it may give ranges of num-bers rather than exact dates.

Many fossils were discovered before theadvent of modern stratigraphy. Often we can nolonger determine their original stratigraphicplacement. Furthermore, fossils aren’t alwaysdiscovered in volcanic layers. Like 14C dating, theK/A technique applies to a limited period of thefossil record. Because the half-life of 40K is solong, the technique cannot be used with materi-als less than 500,000 years old.

Other radiometric dating techniques can beused to cross-check K/A dates, again by usingminerals surrounding the fossils. One suchmethod, uranium series dating, measures fissiontracks produced during the decay of radioactive

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East Africa’s Great Rift Valley runs through Ethiopia,Kenya (shown here), and Tanzania. What datingtechnique(s) can be used in this volcanic region?

uranium (238U) into lead. Two other radiometrictechniques are especially useful for fossils thatcannot be dated by 14C (up to 40,000 B.P.) or 40K(more than 500,000 B.P.). These methods are ther-moluminescence (TL) and electron spin resonance(ESR). Both TL and ESR measure the electronsthat are constantly being trapped in rocks andminerals (Shreeve 1992). Once a date is obtained

for a rock found associated with a fossil,the date also can be applied to that fos-sil. The time spans for which the variousabsolute dating techniques are applica-ble are summarized in Table 5.1.

Early Primates

Primates have lived during the past65 million years, the Cenozoic era,which has seven epochs (see Figure

5.1). When the Mesozoic era ended, and theCenozoic began, some 65 million years ago,North America was connected to Europe, but notto South America. (The Americas joined some20,000,000 years ago.) Over millions of years, thecontinents have “drifted” to their present loca-tions, carried along by the gradually shiftingplates of the Earth’s surface (Figure 5.2).

During the Cenozoic, most land masses hadtropical or subtropical climates. The mesozoic erahad ended with a massive worldwide extinctionof plants and animals, including the dinosaurs.Thereafter, mammals replaced reptiles as thedominant large land animals. Trees and flower-ing plants soon proliferated, supplying arborealfoods for the primates that eventually evolved tofill the new niches.

According to the arboreal theory, primatesbecame primates by adapting to arboreal life. Theprimate traits and trends discussed in the lastchapter developed as adaptations to life high upin the trees. A key feature was the importance ofsight over smell. Changes in the visual apparatuswere adaptive in the trees, where depth percep-tion facilitated leaping. Grasping hands and feetwere used to crawl along slender branches.Grasping feet anchored the body as the primatereached for foods at the ends of branches. Earlyprimates probably had omnivorous diets basedon foods available in the trees, such as flowers,fruits, berries, gums, leaves, and insects. Theearly Cenozoic era witnessed a proliferation offlowering plants, attracting insects that were tofigure prominently in many primate diets.

Matt Cartmill (1972, 1992) notes that althoughprimate traits work well in the trees, they aren’tthe only possible adaptations to arboreal life.Squirrels, for example, do just fine with clawsand snouts and without binocular vision. Some-thing else must have figured in primate evolu-tion, and cartmill suggests a visual predationhypothesis. This is the idea that binocular vision,grasping hands and feet, and reduced clawsdeveloped because they facilitated the capture ofinsects, which figured prominently in the earlyprimate diet. According to this theory, early pri-mates first adapted to bushy forest undergrowthand low tree branches, where they foraged forfruits and insects. Particularly in pursuinginsects, early primates would have relied heavilyon vision. Close-set eyes permitted binocularvision and depth perception. Such a visual appa-ratus would have allowed early primates tojudge the distance to their prey without movingtheir heads. They would have hunted like cats

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Table 5.1Absolute Dating Techniques

Technique Abbreviation Materials Dated Effective Time Range

Carbon 14 14C Organic materials Up to 40,000 yearsPotassium-argon K/A and 40K Volcanic rock Older than 500,000 yearsUranium series 238U Minerals Between 1,000 and 1,000,000Thermoluminescence TL Rocks and minerals Between 5,000 and 1,000,000Electron spin resonance ESR Rocks and minerals Between 1,000 and 1,000,000

xx–xx

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Figure 5.2Placement of Continents at the End of the Mesozoic

NorthAmerica

Eurasia

India

Africa

SouthAmerica

Antarctica

Australia

When the Mesozoic era ended, and the Cenozoic began, some 65million years ago, North America was connected to Europe, but not to South America.

According to one theory, binocular vision and manipu-lative hands developed among primates because theyfacilitated the capture of insects. What is this theorycalled? Here a Colombian squirrel monkey uses itshands and eyes to eat a katydid.

and owls. The snout would have been reduced,with a less acute sense of smell, as the eyes camecloser together. Early primates would have heldon with their grasping feet as they snared theirprey with their hands. Several living prosimiansretain the small body size and insectivorous dietthat may have characterized the first primates.Jurmain (1997) suggests that although key pri-mate traits might have evolved first for life in thelower branches, such traits would have becomeeven more adaptive when bug snatching wasdone higher up in the trees.

Early Cenozoic PrimatesThere is considerable fossil evidence that a diver-sified group of primates lived, mainly in Europeand North America, during the second epoch ofthe Cenozoic, the Eocene. On that basis it is likelythat the earliest primates lived during the firstepoch of the Cenozoic, the Paleocene (65–54m.y.a.). The status of several fossils as possiblePaleocene primates has been debated. As there isno consensus on this matter, such fossils are notdiscussed here.

The first fossil forms clearly identified as pri-mates lived during the Eocene epoch (54–38

m.y.a.) in North America, Europe, Africa, andAsia. They reached Madagascar from Africa latein the Eocene. The ancestral lemurs must havetraveled across the Mozambique Channel, whichwas narrower then than it is now, on thick matsof vegetation. Such naturally formed “rafts” havebeen observed forming in East African rivers,then floating out to sea.

In primate evolution, the Eocene was the age ofthe prosimians, with at least 60 genera in twomain families (Adapidae and Omomyidae). Thewidely distributed omomyid family lived inNorth America, Europe, and Asia. The omomyidswere squirrel-sized. But unlike squirrels they hadgrasping hands and feet, used to manipulateobjects and to climb by encircling small branches.Early members of the omomyid family may beancestral to all anthropoids. Later ones may beancestral to tarsiers.

The adapid family was probably ancestral tothe lemur–loris line. The only major differencebetween the Eocene adapids, such as Smilodectes,shown in the photo, and today’s lemurs andlorises is that the latter have a dental comb (seeFigure 5.3). This structure is formed from theincisor and canine teeth of the lower jaw.

Sometime during the Eocene, ancestralanthropoids branched off from the prosimians bybecoming more diurnal (active during the day)and by strengthening the trend favoring visionover smell. Some Eocene prosimians had larger

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Compare this line drawing reconstruction of Shoshonius,a member of the Eocene omomyid family, with a modern tarsier from Mindanao in the Philippines. What similarities and differences do you notice?

brains and eyes, and smallersnouts, than others did. Thesewere the ancestors of the anthro-poids. Anthropoid eyes are ro-tated more forward when com-pared with lemurs and lorises.Also, anthropoids have a fullyenclosed bony eye socket, whichlemurs and lorises lack. Andunlike lemurs and lorises, an-thropoids lack a rhinarium, amoist nose continuous with theupper lip. Anthropoids have adry nose, separate from theupper lip. Another distinguish-ing anthropoid feature has to dowith molar cusps—bumps onthe teeth. The primitive numberof cusps on mammalian lower molars is six. Theanthropoids have lost one or two cusps on theirlower molars, so as to have four or five.

The oldest probable anthropoid discovered sofar is Eosimias, from the Eocene of China (see

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Smilodectes was a member of the lemurlike adapidfamily, which lived during the Eocene. Compare this drawing reconstructing a Smilodectes fromWyoming with a modern ring-tailed lemur fromMadagascar.

Figure 5.3A Dental Comb

Source: Robert Jurmain and Harry Nelson, Introduction to PhysicalAnthropology, 6th ed. (Minneapolis: West Publishing, 1994), p. 210.

A dental comb is a derived trait present amongcontemporary lemurs and lorises but absent inEocene adapids such as Smilodectes.)

chapter opener). The oldest definite anthropoid isCatopithecus, from the late Eocene of egypt. By theend of the Eocene, many prosimian species hadbecome extinct, reflecting competition from thefirst anthropoids.

Oligocene AnthropoidsDuring the Oligocene epoch (38–23 m.y.a.),anthropoids became the most numerous pri-mates. Most of our knowledge of early anthro-poids is based on fossils from Egypt’s Fayumdeposits. This area is a desert today, but 36–31million years ago it was a tropical rain forest.

The anthropoids of the Fayum lived in treesand ate fruits and seeds. Compared withprosimians, they had fewer teeth, reducedsnouts, larger brains, and increasingly forward-looking eyes. Of the Fayum anthropoid fossils,the parapithecid family is the more primitive andis perhaps ancestral to the New World monkeys.The parapithecids were very small (two to threepounds), with similarities to living marmosetsand tamarins, small South American monkeys.One genus of this group, Apidium, is one of themost common fossils in the Fayum beds.

The propliopithecid family seems ancestral tothe catarrhines—Old World monkeys, apes, andhumans. This family includes Aegyptopithecus,which at 13–18 pounds, was the size of a largedomestic cat. The propliopithecids share with thelater catarrhines a distinctive dental formula:2.1.2.3, meaning two incisors, one canine, twopremolars, and three molars. (The formula isbased on one-fourth of the mouth, either the rightor left side of the upper or lower jaw.) The moreprimitive primate dental formula is 2.1.3.3. Mostother primates, including prosimians and NewWorld monkeys, have the second formula, withthree premolars instead of two. Besides theFayum, Oligocene deposits with primate bonesalso have been found in North and West Africa,southern Arabia, China, Southeast Asia, andNorth and South America.

The Oligocene was a time of major geologicaland climatic change. North America and Europeseparated and became distinct continents. TheGreat Rift Valley system of East Africa formed.India drifted into Asia. A cooling trend began,especially in the Northern Hemisphere, whereprimates disappeared.

Miocene Hominoids

The earliest hominoid fossils date to the Mioceneepoch (23–5 m.y.a.), which is divided into threeparts: lower, middle, and upper or late. The earlyMiocene (23–16 m.y.a.) was a warm and wetperiod, when forests covered East Africa. Recallfrom the last chapter that Hominoidea is the super-family that includes fossil and living apes andhumans. For simplicity’s sake, the earliest homi-noids are here called proto-apes, or simply apes.Although some of these may be ancestral to liv-ing apes, none is identical, or often even verysimilar, to modern apes.

ProconsulThe superfamily known as Pliopithecoidea includesseveral species of the genus Proconsul. The Pro-consul group represents the most abundant andsuccessful anthropoids of the early Miocene. Thisgroup lived in Africa and includes three species:Proconsul (P.) africanus, P. nyanzae, and P. major.Possibly descended from the Oligocene propliop-ithecids, these early Miocene proto-apes had teethwith similarities to those of living apes. But theirskeleton below the neck was more monkeylike.Some Proconsul species were the size of a smallmonkey; others, the size of a chimpanzee, usuallywith marked sexual dimorphism. Their dentitionsuggests they ate fruits and leaves.

Their skulls were more delicate than those ofmodern apes, and their legs were longer thantheir arms—more like monkeys. Proconsul prob-ably moved through the trees like a monkey—on four limbs—and lacked the capacity for sus-pension and brachiation displayed by modernapes. Proconsul probably contained the last com-mon ancestor shared by the Old World monkeysand the apes. By the middle Miocene, Proconsulhad been replaced by Old World monkeys andapes.

Fossils of Miocene monkeys and prosimiansare rare; ape fossils are much more common. Likemany living apes, those of the Miocene were for-est dwellers and fruit eaters. They lived in areasthat, as the forests retreated, monkeys wouldeventually colonize. In the late Miocene, mon-keys became the most common anthropoid in theOld World (except for humans).

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Why did the Old World mon-keys thrive as the Miocene apesfaded? The probable answer wasthe monkeys’ superior ability toeat leaves. Leaves are easier to getthan fruits, which are typical apefoods. As the forests retreated atthe end of the Miocene, most apeswere restricted to the remainingtropical rain forests in areas of(mainly West) Africa and South-east Asia. Monkeys survived overa wider area. They did so becausethey could process leaves effec-tively. Monkey molars developedlophs: ridges of enamel that runfrom side to side between thecusps of the teeth. Old World monkeys have twosuch lophs, so their molars are called bilophodont.Such lophs slice past each other like scissorblades, a good way to shear a leaf.

Some species of Proconsul may have beenancestral to the living African apes. Proconsul alsomay be ancestral to the Old World monkeys. Pro-consul had all the primitive traits shared by apesand Old World monkeys and none of the derivedtraits of either. Primitive traits are those passed onunchanged from an ancestor, such as the five-cusped molars of the apes, which are inheritedfrom an old anthropoid ancestor. Derived traitsare those that develop in a particular taxon afterthey split from their common ancestor withanother taxon. Examples are bilophodont molarsamong Old World monkeys. The Old Worldmonkeys have derived bilophodont molars andprimitive quadrupedal bodies. The apes haveprimitive molars and derived brachiating bodies.Proconsul had both primitive teeth and a primi-tive quadrupedal body.

Afropithecus and KenyapithecusDuring the early Miocene, Africa was cut off bywater from Europe and Asia. But during the mid-dle Miocene, Afro-Arabia drifted into Eurasia,providing a land connection between the threecontinents. Migrating both ways—out of and intoAfrica—after 16 m.y.a. were various animals,including hominoids. Proto-apes were the mostcommon primates of the middle Miocene (16–10m.y.a.). Over 20 species have been discovered.

(See Figure 5.4.) Their teeth retain the primitiveanthropoid five-cusped molar pattern.

During the middle Miocene, the hominoidsspread widely, in Europe, Asia, and Africa. EastAfrican apes of the middle Miocene include Afro-pithecus, Equatorius, and two species of Kenyapithe-cus, one earlier, one later. Afropithecus is a largeMiocene hominoid from northern Kenya, dated to18 to 16 m.y.a. (Leakey, Leakey, and Walker 1988).The Afropithecus remains consist of skull, jaw, andpostcranial (below the head) fragments. Afropithe-cus seems to have been a slow-moving arborealape, with large projecting front teeth (similar tothose of the modern African apes).

A recent discovery is a 15-million-year-oldpartial skeleton assigned to a new genus Equato-rius africanus. The find, from Kenya, consists ofupper incisors, a lower jaw with teeth, and bonesfrom the arm, shoulder, collarbone, chest, wrists,fingers, and vertebrae, all belonging to a singlemale. In its skeleton Equatorius is more modernthan earlier hominoids, suggesting that it usedthe ground more frequently than earlier homi-noids did.

There are clear similarities between Equatoriusand the earlier of the two species of Kenyapithe-cus. Based on these similarities, the discoverersof Equatorius have suggested that the earlierKenyapithecus species should be reclassified as

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A skull of Proconsul africanus from the Kenya NationalMuseum. Why might it be significant that Proconsul hadall the primitive traits shared by apes and Old Worldmonkeys and none of the derived traits of either?

Equatorius. The two Kenyapithecus species thathave been recognized traditionally are K. africanus(earlier) and K. wickeri (later). Equatorius and K.africanus represent an older pattern. K. wickeriillustrates a more modern pattern—more liketoday’s great apes. K. wickeri’s dental pattern alsois found in the teeth of an unnamed ape from amiddle Miocene site in Turkey (Ward et al. 1999).

Equatorius and Afropithecus are probable stemhominoids: species somewhere on the evolutionaryline near the origins of the modern ape group.Stem hominoids are considered too primitive tobe the direct ancestors of living apes and humans.

SivapithecusMiddle and late Miocene apes are often groupedin two families: Ramapithecidae and Dryopitheci-dae. The ramapithecids lived during the middle

and late Miocene in Europe, Asia, and Africa.There are at least two ramapithecid genera: Siva-pithecus and Gigantopithecus.

Sivapithecus fossils were first found in theSiwalik Hills of Pakistan. They include specimensformerly called “Ramapithecus” from that region,along with fossil apes from Turkey, China, andKenya. The earlier forms of Sivapithecus that livedin Asia during the middle Miocene may representthe common ancestor of the orangutan and theAfrican apes. A late Miocene find with an almostcomplete face from Pakistan’s Potwar Plateaushows many similarities to the face of the modernorangutan. Because of facial and dental similari-ties, Sivapithecus of the late Miocene is now seenas ancestral to the modern orangutan. The orang-utan line appears to have separated from the oneleading to the African apes and humans morethan 13 million years ago.

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Figure 5.4The Geographic Distribution of Known Miocene Apes

Could it be that Gigantopithecus did not goextinct, but survives today as the yeti (“abom-inable snowman” of the Himalayas) or Sasquatch(reportedly sighted in the Pacific Northwest)?Probably not. These creatures are based on leg-end, not fact. Survival of a species requires a suf-ficiently large breeding population. Given itsdietary demands, Gigantopithecus would surelybe detectable and have an observable environ-mental effect. Never have Gigantopithecus fossilsor teeth been discovered in the Western Hemi-sphere. Nor are the areas of yeti and Sasquatchsightings ones in which Gigantopithecus would fitadaptively.

DryopithecusThe dryopithecids lived in Europe during themiddle and late Miocene. This group probablyincludes the common ancestor of the lesser apes(gibbons and siamangs) and the great apes. Thefirst fossil member of the Dryopithecus group(Dryopithecus fontani) was found in France in1856. The five-cusp and fissure pattern of itsmolar teeth, known as the Y-5 arrangement, istypical of the dryopithecids and of hominoids ingeneral. Other dryopithecids have been found inHungary, Spain, and China.

The continental drift that created the landbridge between Africa and Eurasia as the middleMiocene began also triggered mountain buildingand climatic change. With a cooler, drier climate,forest patches, dry woodlands, and grasslandsreplaced extensive tropical forests in East Africaand South Asia. The cooling trend continuedthrough the late Miocene (10–5 m.y.a.). As grass-lands spread, the stage was set for the diver-gence of the lines leading to humans, gorillas,and chimps.

OreopithecusIs upright bipedalism unique to hominids? Arecent reanalysis of the fossil remains of anancient Italian ape suggests otherwise. Oreopithe-cus bambolii, which lived seven to nine millionyears ago, apparently spent much of its timestanding upright and shuffling short distances tocollect fruit and other foods. This mode of loco-motion contrasts with those of other fossil andliving apes, which climb, brachiate, or knucklewalk. The first Oreopithecus fossils were foundmore than 100 years ago in central Italy. The tax-onomic placement and evolutionary significanceof Oreopithecus have been debated for decades.Similarities have been noted between this Italianape and both the ramapithecid and the dryop-ithecid families.

Meike Kohler and Salvador Moya-Sola (1997)recently reanalyzed Oreopithecus remains in theNatural History Museum in Basel, Switzerland.These skeletal pieces represented the lower back,pelvis, leg, and foot. The scientists found thecreature’s lower body to be intermediate betweenthose of apes and early hominids. Like earlyhominids, Oreopithecus had a lower back that

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A reconstruction of Gigantopithecus by RussellCiochon and Bill Munns. Munns is shown here with“Giganto.” What would be the likely environmentaleffects of a population of such large apes?

arched forward, a vertically aligned knee joint,and a similar pelvis. All these features are signifi-cant for upright walking. However, Oreopithecushad a unique foot. Its big toe splayed out 90degrees from the other toes, all of which wereshorter and straighter than those of modern apes.The foot’s birdlike, tripod design was probablyassociated with a short, shuffling stride. Consid-ering the entire postcranium (the area behind orbelow the head—the skeleton), there are substan-tial similarities between Oreopithecus, Dryopithe-cus, and the living great apes and hominids.

A Missing Link?

The idea of “the missing link” goes back to an oldnotion called the “Great Chain of Being.” Thiswas the theological belief that various entitiescould be placed in a progressive chain. Among

life forms, humans were at the top of the chain.Above them stood only angels and divinity.Below them were the apes, most clearly theAfrican apes. But humans seemed too exalted,too different from those apes, to be directlylinked to them. Between humans and the apes,there needed to be some form more progressivethan the apes—some sort of missing link in theGreat Chain of Being. Although modern sciencedoes not endorse the Great Chain of Being, itdoes recognize that our ancestor was a life formthat differed from contemporary gorillas andchimps. Humans are not descended from gorillasor chimps. Rather, humans and the African apesshare a common ancestor—a creature that waslike the African apes in some ways, like humansin others. Over time all three species haveevolved and have diverged from one another.

Human ancestors almost certainly divergedfrom those of chimps and gorillas late in theMiocene epoch, between eight and five million

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What is maceration? How mightit be useful to archaeologists andbiological anthropologists? Wouldthe ethical issues involved be dif-ferent with primates versus thelynx described here?

In January 2000 I took aPracticum in Archaeology class.We were each to conduct our ownresearch project. I chose to com-plete a maceration project for our

faunal laboratory. The carcass Ichose to work with was that of aninfirm Canadian Lynx, which hadbeen euthanized and donated bythe zoo. My objective was toexamine the condition of itsbones, to determine how its for-mer health would be reflected inits skeleton.

By macerating an animal ofknown age, with a documented

medical history and stable diet,we could compare this animal withone reared in the wild and look atdifferences in health. To maceratean animal, you remove the peltand musculature from the bones,then soak the skeleton in chemi-cals to remove the grease. Oncethe bones are dry, they are dippedin preservative to keep them fromdecaying. I examined the bonesand teeth for indications of illhealth. In this particular lynx,advanced age had resulted in theossification of many joints. Thiswould have made extendedmovement quite painful. I was sur-prised by the damage to herjoints. The excessive developmentof bone around the joints was likethat in humans with osteoarthritis,

beyond the classroomMaceration of a Canadian Lynx

BACKGROUND INFORMATION

Student: Barbara HewittSupervising Professor: Ariane BurkeSchool: University of ManitobaYear in School/Major: Graduated in spring 2000/AnthropologyFuture Plans: Graduate school in forensic archaeology

and osteology in EnglandProject Title: Maceration of a Canadian Lynx

years ago. The evolutionary line leading toorangutans probably split from the one leadingto humans, chimps, and gorillas around 13 m.y.a.drawing on the genus names Homo, Gorilla, andPan (chimpanzee), I use the nickname “Hogo-pans” to refer to the ancestral population of lateMiocene hominoids that eventually split threeways to produce humans, gorillas, and chimps.Hogopans is not a scientific term, just a conve-nient nickname, for the common ancestors ofhumans and the African apes.

No more than eight million years ago, theHogopans diverged into three groups (Fisher1988a). They split up by occupying different envi-ronmental niches. Separated in space, theybecame reproductively isolated from oneanother—leading to speciation. Ancestral gorillaseventually occupied forested zones of the moun-tains and lowlands of equatorial Africa. Theydeveloped a diet based on leaves, shoots, andbulk vegetation. Chimps evolved into frugivores

(fruit eaters) in the forests and woodlands of Cen-tral Africa. Ancestral hominids spent more timein the open grasslands, or savannas, of easternand southern Africa.

Where are the fossils of the Hogopans? As wehave seen, Miocene deposits in Africa, Asia, andEurope have yielded an abundance of hominoidfossils (see Figure 5.4). Some of these may haveevolved into modern apes and humans, but oth-ers became extinct. Hogopan identity remains amystery. Do Hogopan fossils remain to be found?Perhaps they have been found already but havenot been generally recognized as Hogopans.

Formerly, as mentioned, certain Asian fossilssuch as Sivapithecus and “Ramapithecus” wereanalyzed as possible Hogopans. Most scientistshave now excluded these Miocene hominoidsfrom the family tree of humans, chimps, andgorillas, considering Sivapithecus a probableancestor of orangs. Discovered in Greece in 1989,the mid- to late-Miocene ape Ouranopithecus

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which gave me a good idea ofhow painful and debilitating thatdisease can be. I detected a com-pletely healed break in the rightfront humerus (upper arm bone),indicating that the animal hadbeen healthy and well nourished

when the break happened for thebreak to have healed so well. Onlyfour teeth remained; this lynxcould not eat solid food when shedied.

The most challenging aspect ofthis project was that I workedunassisted. With only an instruc-tion manual to follow, and an occa-sional consultation with my super-visor, I learned how to mosteffectively skin and deflesh an ani-mal. The processing and analysis ofthe skeleton took far longer than Iexpected. A mistake during pro-cessing gave me a deeper appreci-ation for the people who analyzefaunal remains in an archaeologicalcontext. The bones had beenprocessed, and were laid out fordrying, when another studentmoved them without moving thelabels as well. After that, eachbone had to be indentified againand laid out for relabeling.

The best part of this project waswhat it taught me about the devel-opment of bones and the talent ofpeople who identify and work withthem. In trying to reidentify theelements of the lynx skeleton, Irealized exactly how tough itwould be to pick up a bone (orfragment of a bone) from anarchaeological site and determinewhich bone it is, what species itcomes from, and the pathology ofthat particular animal or person. Ithink I learned more about theinherent difficulties of faunal iden-tification in an archaeological con-text from that error than from anyother aspect of the project.

The bones of the lynx that Imacerated and processed havealready proved useful to severalfaunal anlysis classes, and to ourzooarchaeologists when asked toidentify bones brought to thedepartment for identification.

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lived in Europe some 9–10 m.y.a. This find maybe linked to the living African apes and even tohominids (Begun, Ward, and Rose 1997). Onetrait that Ouranopithecus shares with the modernAfrican apes is frontal sinuses.

Because of Miocene finds reported and ana-lyzed during the past decade, some scientists arepondering a new scenario for ape and humanevolution. As mentioned, during the middleMiocene, after a land bridge connected Africaand Eurasia, hominoids spread from Africa intoAsia and Europe where they diversified into thegroups discussed above. At the same time, theapes’ forest habitat was shrinking in East Africa,and the number of ape species there along with it.In the middle and late Miocene, there appears tohave been much more ape diversity in Europeand Asia than in Africa. During the late Miocene,Old World monkeys took over from the dwin-dling African apes in many areas they onceinhabited. The new hominoid evolutionary sce-nario, proposed but hardly established, is that theline leading to the African apes and hominidsmay have emerged in Europe, with a hominoidsuch as Ouranopithecus. Then there would havebeen a return migration to Africa, where thediversification of the Hogopans actually tookplace between five and eight million years ago.Continued work by fossil hunters, analysts, andtaxonomists may eventually reconcile the mainissues involving the Miocene apes in relation totheir living successors, to whom we turn in thenext chapter.

The Great Chain of Being—a powerful visual metaphorfor a divinely inspired universal hierarchy ranking allforms of higher and lower life. From Didacus Valades,Rhetorica Christiana (1579). What can you tell aboutthe levels in the hierarchy?

summary1. Anthropologists and paleontologists use stratig-

raphy and radiometric techniques to date fossils.Carbon-14 (14C) dating is most effective with fos-sils less than 40,000 years old. Potassium-argon(K/A) dating can be used for fossils older than500,000 years. 14C dating is done on organic mat-ter, whereas the K/A, 238U, TL, and ESR datingtechniques are used to analyze minerals that liebelow and above fossils.

2. Primates have lived during the past 65 millionyears, the Cenozoic era, with seven epochs: Pale-ocene, Eocene, Oligocene, Miocene, Pliocene,Pleistocene, and Recent. The arboreal theorystates that primates evolved by adapting to lifehigh up in the trees. The visual predation hypoth-esis suggests that key primate traits developedbecause they facilitated the capture of insects.

3. The first fossils clearly identified as primates livedduring the Eocene (54–38 m.y.a.), mainly in NorthAmerica and Europe. The omomyid family maybe ancestral to the anthropoids and the tarsier.The adapid family was probably ancestral to thelemur–loris line.

4. During the Oligocene (38–23 m.y.a.), anthro-poids became the most numerous primates. Theparapithecid family may be ancestral to the NewWorld monkeys. The propliopithecid family,including Aegyptopithecus, seems ancestral tothe catarrhines—Old World monkeys, apes, andhumans.

5. The earliest hominoid fossils are from theMiocene (23–5 m.y.a.). Africa’s Proconsul groupcontained the last common ancestor shared bythe Old World monkeys and the apes. Since themiddle Miocene Africa, Europe, and Asia havebeen connected. Proto-apes spread beyondAfrica and became the most common primates ofthe middle Miocene (16–10 m.y.a.). East Africanapes of the middle Miocene include Afropithe-cus, Equatorius, and Kenyapithecus. Middle and

late Miocene apes are often grouped in two fam-ilies: Ramapithecidae and Dryopithecidae. Theramapithecids included at least two genera: Siva-pithecus and Gigantopithecus. Sivapithecus wasancestral to the modern orangutan. Asia’s Gigan-topithecus, the largest primate ever to live, per-sisted for millions of years, finally coexisting withHomo erectus.

6. The dryopithecids, found mainly in Europe, prob-ably include the common ancestor of the lesserapes (gibbons and siamangs) and the great apes.Oreopithecus bambolii, which lived 7–9 m.y.a.,was an ape that stood upright while collectingfruit and other foods. There are skeletal similari-ties between Oreopithecus, dryopithecus, andthe living great apes and hominids. Ouranopithe-cus, which lived in Europe some 9–10 m.y.a., maybe linked to chimps, gorillas, and humans. Anthro-pologists have yet to identify the fossils of theHogopans, the common ancestors of humans,gorillas, and chimps. However, biochemical evi-dence strongly suggests that the Hogopans beganto diverge in Africa during the late Miocene.

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key termsabsolute dating Dating techniques that establishdates in numbers or ranges of numbers; examplesinclude the radiometric methods of 14C, K/A, 238U, TL,and ESR dating.

adapids Early (Eocene) primate family ancestral tolemurs and lorises.

arboreal theory Theory that the primates evolvedby adapting to life high up in the trees, where visualabilities would have been favored over the sense ofsmell, and grasping hands and feet would have beenused for movement along branches.

dryopithecids Zoological ape family living inEurope during the middle and late Miocene; probablyincludes the common ancestor of the lesser apes (gib-bons and siamangs) and the great apes.

m.y.a. Million years ago.

omomyids Early (Eocene) primate family found inNorth America, Europe, and Asia; early omomyidsmay be ancestral to all anthropoids; later ones may beancestral to tarsiers.

Paleoanthropology Study of hominid and humanlife through the fossil record.

postcranium The area behind or below the head;the skeleton.

Proconsul Early Miocene genus of the pliopithecoidsuperfamily; the most abundant and successful anthro-poids of the early Miocene; the last common ancestorshared by the Old World monkeys and the apes.

relative dating Dating technique, e.g., stratigraphy,that establishes a time frame in relation to other strataor materials, rather than absolute dates in numbers.

Sivapithecus Widespread fossil group first found inPakistan; includes specimens formerly called “Ramap-ithecus” and fossil apes from Turkey, China, and Kenya;early Sivapithecus may contain the common ancestorof the orangutan and the African apes; late Sivapithe-cus is now seen as ancestral to the modern orang.

stratigraphy Science that examines the ways inwhich earth sediments are deposited in demarcatedlayers known as strata (singular, stratum).

taphonomy The study of the processes that affectthe remains of dead animals, such as their scatteringby carnivores and scavengers, their distortion by vari-ous forces, and their possible fossilization.

visual predation theory Theory that the primatesevolved in lower branches and undergrowth by devel-oping visual and tactile abilities to aid in hunting andsnaring insects.

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critical thinking questions1. What are the pluses and minuses of relying on the

fossil record to reconstruct evolution? Besidesfossils, what are other lines of evidence for pri-mate and human evolution?

2. What are the strengths and limitations of relativedating? Of absolute dating?

3. What are some unanswered questions aboutearly primate evolution? What kinds of informa-tion would help provide answers?

4. Watch a squirrel move about. How do its move-ments compare with a monkey’s movements?With a cat’s movements? With your own? Whatdo these observations suggest to you about thatanimal’s ancestral habitat?

5. What’s your opinion about the merits of the arbo-real theory versus the visual predation theory ofprimate origins?

6. There have been reported sightings of “bigfoot”in the Pacific Northwest of North America and ofthe yeti (abominable snowman) in the Himalayas.What facts about apes lead you to question suchreports?

7. Who were the Hogopans, when and where didthey probably live, and what is the fossil evidencefor their existence?

suggested additional readingsBegun, D. R., C. V. Ward, and M. D. Rose 1997 Description: Function, Phylogeny, and Fossils:

Miocene Hominoid Evolution andAdaptations. New York: Plenum. A collectionof very up-to-date scientific articles on theMiocene apes.

Boaz, N. T.1999 Essentials of Biological Anthropology. Upper

Saddle River, NJ: Prentice Hall. Basic text inphysical anthropology, with information onprimate evolution and paleoanthropology.

Ciochon, R. L., J. Olsen, and J. James1990 Other Origins: The Search for the Giant Ape

in Human Prehistory. New York: BantamBooks. In search of Gigantopithecus.

Eldredge, N.1997 Fossils: The Evolution and Extinction of

Species. Princeton, NJ: Princeton UniversityPress. What fossils tell us about the naturalhistory of species.

Fleagle, J. G.1999 Primate Adaptation and Evolution, 2nd ed.

San Diego: Academic Press. Excellentintroduction to adaptation of past andpresent primate species.

Hrdy, S. B.1999 The Woman That Never Evolved, rev. ed.

Cambridge, MA: Harvard University Press.Revised edition of a well-known contributionto primate and human evolution.

Kemp, T. S. 1999 Fossils and Evolution. New York: Oxford

University Press. Interpreting the FossilRecord.

Kimbel, W. H., and L. B. Martin, eds. 1993 Species, Species Concepts, and Primate

Evolution. New York: Plenum. The evolutionof primate species.

MacPhee, R. D. E., ed.1993 Primates and Their Relatives in Phylogenetic

Perspective. New York: Plenum. Discussion ofthe primate family tree and its evolution.

Napier, J. R., and P. H. Napier 1985 The Natural History of the Primates.

Cambridge, MA: MIT Press. The adaptationsof primates, past and present.

Park, M. A.1999 Biological Anthropology, 2nd ed. Mountain

View, CA: Mayfield. A concise introduction,with a focus on scientific inquiry.

Wade, N., ed.1998 The Science Times Book of Fossils and

Evolution. New York: Lyons Press. Articles on fossils and evolution from the New YorkTimes.

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internet exercises1. Dating Techniques: Go to the USGS site on Fos-

sils, Rocks, and Time, http://pubs.usgs.gov/gip/fossils/contents.html, and read through all thesections.

a. How do researchers use the law of superpo-sition to date fossils?

b. What are isotopes? How are they used byresearchers to calculate numeric dates forfossils?

c. How do relative and absolute/numeric dat-ing techniques complement each other?

2. Bigfoot: Read Lorraine Ahearn’s article “BigfootTheory: Reality is What You Make of It,” which is areport about a 1999 Bigfoot conference, http://www.bigfootcentral.com/articlesbc/bf_articles/greens.asp.

a. This chapter reported that some peoplebelieve that Bigfoot is a living ancestor ofGigantopithicus blackei. What are the argu-ments for and against this claim?

b. What are some other Bigfoot theories pre-sented in this article? How could you goabout testing them?

c. What is your opinion about Bigfoot? Howwould you go about testing it?

See Chapter 5 on your CD-ROM for additional reviewand interactive exercises. See your McGraw-HillOnline Learning Center for more.