2. 7
C H A P T E R
THE PRIMATES
7-2

3. THE PRIMATES Our Place Among Primates Homologies and Analogies
Primate Tendencies
Prosimians
Monkeys
Apes
Behavioral Ecology and Fitness
Primate Evolution
Chronology
Early Primates
Miocene Hominoids 3

4. THE PRIMATES How and why are monkeys and apes similar to humans?
When, where, and how did the first primates, monkeys, apes, and hominids evolve?
How did diversity among Miocene proto-apes figure in hominid origins?

5. PRIMATOLOGY
Primatology: the study of nonhuman primates—fossils and living apes, monkeys, and prosimians—including their behavior and social life
Terrestrial monkeys and apes: primates that live on the ground rather than in trees
Great apes, specifically chimpanzees and gorillas
Most closely related to us

6. OUR PLACE AMONG PRIMATES
Similarities between humans and apes evident in anatomy, brain structure, genetics, and biochemistry
Taxonomy: assignment of organisms to categories
Phylogeny: genetic relatedness based on common ancestry
Hominoidea (hominoids): a superfamily containing humans and apes

7. OUR PLACE AMONG PRIMATES
Homologies: similarities that organisms share because of a common ancestry
Mammals
Primates share structural and biochemical homologies that distinguish them from other mammals
Resemblances inherited from common early primate ancestors

8. Figure 7.1: The Principal Classificatory Units of Zoological Taxonomy8

9. Table 7.1: The Place of Humans (Homo sapiens) in Zoological Taxonomy9

10. Table 7.2: Primate Taxonomy10

11. HOMOLOGIES AND ANALOGIES
Extensive biochemical homologies between apes and humans confer a common ancestry
Analogies: similar traits that arise if species experience similar selective forces and adapt to them in similar ways
Convergent evolution: process by which analogies are produced

12. HOMOLOGIES AND ANALOGIES
Hominid: the zoological family that includes fossils and living humans, chimpanzees, gorillas, and their common ancestors
Tribe hominini describes all human species that have ever existed, excluding chimps and gorillas
Scientists today use the word hominin to describe the zoological family of humans but not chimps and gorillas

13. Figure 7.2: Primate Family Tree13

14. PRIMATE TENDENCIES
Primates have varied because of adapting to diverse ecological niches
Modern primates share homologies reflecting a common arboreal (living in trees) heritage

15. PRIMATE TENDENCIES
Many trends in primate evolution best exemplified by anthropoids: monkeys, apes, and humans constituting the suborder Anthropoidea
Prosimians: primate suborder that includes lemurs, lorises, and tarsiers

16. PRIMATE TENDENCIES
Grasping: opposable thumbs can touch all other fingers
Adaptation of hominins to bipedal locomotion: two-footed, upright locomotion
Shift from smell to sight
Hand, rather than nose, is main touch organ
Increased brain complexity
Parental investment in single offspring
Sociality

17. PROSIMIANS Primate order has two suborders:
Anthropoids
Early history of primates limited to prosimian-like animals known through the fossil record
The first anthropoids appeared more than 40 million years ago

18. PROSIMIANS
Some prosimians managed to survive in Africa and Asia because they adapted to nocturnal life
They do not compete with anthropoids, which are active during the day
Lemurs
Tarsiers
Lorises

19. MONKEYS
All anthropoids share resemblances that can be considered trends in primate evolution
Anthropoid suborder has two infraorders:
Platyrrhines: flat-nosed, New World monkeys
Catarrhines: sharp-nosed, Old World monkeys, hominoids

20. MONKEYS All New World monkeys, and many Old World ones, are arboreal
Monkeys move differently from apes and humans
Their arms and legs move parallel to each other
Most monkeys have tails

21. NEW WORLD MONKEYS Live in the forests of Central and South America
Have prehensile, or grasping, tails
With one exception, all monkeys, apes, and humans are diurnal

22. Figure 7.3: Nostril Structure of Catarrhines and Platyrrhines22

23. OLD WORLD MONKEYS Terrestrial and arboreal
Significant distinctions exist between arboreal and terrestrial Old World monkeys
Size: arboreal monkeys smaller than terrestrial ones
Sexual dimorphism: marked differences in male and female anatomy and temperament
Terrestrial males significantly larger and fiercer than terrestrial females, but little or no such differentiation exists among arboreal monkeys

24. APES Old World monkeys have separate superfamily (Cercopithecoidea)
Humans and apes make up hominoid superfamily (Hominoidea)
Subdivided into families:
Great apes: orangutans, gorillas, chimpanzees
Lesser (smaller) apes: gibbons, siamangs
The third African ape: humans

25. APES Live in forest and woodlands
Light and agile gibbons are completely arboreal
Skilled brachiation: hand-over-hand movement through the trees
Heavier gorillas, chimpanzees, and adult male orangutans spend considerable time on the ground
Ape behavior and anatomy reveal past and present adaptation to arboreal life

26. GIBBONS Smallest of the apes
Spend most of their time just below the forest canopy
Use arms as balance when they occasionally walk erect
Tend to live in primary groups composed of permanently bonded males and females and their preadolescent offspring

27. Figure 7.4: The Limb Ratio of the Arboreal Gibbon and Terrestrial Homo27

28. ORANGUTANS Two existing species Marked sexual dimorphism
Male is between chimps and gorillas in size
Move between arboreal and terrestrial habitats
Tend to be solitary
Tightest social units: females and preadolescent young

29. GORILLAS Three subspecies: Western lowland Eastern lowland Mountain
Full-grown male may be 400 pounds, 6 feet tall
Marked sexual dimorphism
Spend little time in trees
Live in a troop of males and females with their offspring

30. CHIMPANZEES Two kinds of chimpanzee: Common (Pan troglodytes)
Pygmy (Pan paniscus)
Adult males weigh 100 to 200 pounds
Less sexual dimorphism than gorillas
Social organization relatively well known
Chimps greet with gestures, facial expressions, and calls

31. BONOBOS Belong to species Pan paniscus
Live in humid forests of Democratic Republic of Congo
Adult males average 95 pounds
Female-centered communities
Peace loving
Egalitarian
Frequently use sex to avoid conflict within community

32. BEHAVIORAL ECOLOGY AND FITNESS
Behavioral ecology: study of evolutionary basis for behavior
Assumes genetic features of any species reflect a long history of differential reproductive success
Individual fitness measured by number of direct descendants an individual has
Inclusive fitness is measured by genes one shares with relatives

33. BEHAVIORAL ECOLOGY AND FITNESS
Maternal care always makes sense in terms of the reproductive fitness theory, because females know that offspring are their own
If male cannot be sure about an offspring’s paternity, it may make sense to invest in a sister’s offspring, because of shared genes

34. PRIMATE EVOLUTION
Fossil record offers evidence for no more than 5 percent of extinct primates
Discussions of primate and human evolution must be tentative

35. CHRONOLOGY Paleozoic (544–245 m.y.a.—million years ago)
Era of ancient life—fish, amphibians, and primitive reptiles
Mesozoic (245–65 m.y.a.)
Era of middle life—reptiles, including dinosaurs
Cenozoic (65 m.y.a.–present)
Era of recent life—birds and mammals
Each era is divided into periods, and the periods are divided into epochs

36. CHRONOLOGY Anthropologists concerned with Cenozoic era:
Tertiary period:
Paleocene
Eocene
Oligocene
Miocene
Pliocene
Quaternary period:
Pleistocene
Holocene (or Recent)

37. Figure 7.5: Periods and Epochs of the Cenozoic Era37

38. Figure 7.6: Placement of Continents at the End of the Mesozoic38

39. EARLY PRIMATES
During Cenozoic, most land masses had tropical or subtropical climates
Arboreal theory: primates became primates by adapting to arboreal life
Importance of sight over smell
Development of depth perception facilitated leaping
Grasping hands and feet

40. EARLY CENOZOIC PRIMATES
The earliest primates most likely lived during the first part of the Cenozoic, the Paleocene (65–54 m.y.a.)
Eocene (54–38 m.y.a.) was age of prosimians, with at least 60 different genera in two families

41. EARLY CENOZOIC PRIMATES
Anthropoids branched off from prosimians during Eocene
Eyes rotated forward
Fully enclosed bony eye socket developed
A dry nose is separated from an upper lip
By end of the Eocene, many prosimian species extinct, reflecting competition from anthropoids

42. OLIGOCENE ANTHROPOIDS
During the Oligocene (38–23 m.y.a.), anthropoids became most numerous primates
Of the Fayum anthropoid fossils, one group is more primitive and perhaps ancestral to New World monkeys
Another Fayum group seems ancestral to catarrhines—Old World monkeys, apes, and humans

43. MIOCENE HOMINOIDS
Earliest hominoid fossils date to the Miocene epoch (23–5 m.y.a.)
Hominoids—zoological superfamily that includes extinct and living apes and hominins—called proto-apes, but none are identical to or very similar to modern apes

44. PROCONSUL
Proconsul: represents most abundant and successful anthropoids of early Miocene
Teeth similar to those of living apes
Skeleton below the neck more monkeylike
Dentition suggests they ate fruits and leaves
By middle Miocene, Proconsul replaced by Old World monkeys and apes

45. LATER MIOCENE APES Gigantopithecus Confined to Asia
Persisted for millions of years, from Miocene until 400,000 years ago
Largest ape that ever lived (1,200 pounds; 10 feet tall)
Two species: one coexisted with H. erectus in China and Vietnam; another, much earlier (5 m.y.a.), lived in northern India

46. PIEROLAPITHECUS CATALAUNICUS
Discovered in Spain
May be last common ancestor of world’s living great apes
Lived around 13 million years ago
Well adapted for tree climbing and knuckle walking on the ground
Probably a fruit eater