Chapter 5: Primates

1. Chapter 5: Primates

2. What is a Primate? • First, primates are members of the vertebrate class: Mammalia • + 4000 mammals • Primates are part of the subgroup of placental mammals

3. Three types of primates • Prosimians (pre-monkeys) • Monkeys (Old World and New World) • Apes

4. Common Mammal Traits • Fur (or body hair in Humans) • Long gestation & live birth (relative to other types of organisms) • Heterodontism (different kinds of specialized teeth) • Ability to maintain constant body temp (Homeothermy) • Increased brain size (greater ability for learning and behavioral flexibility)

5. Characteristics of Primates • Difficult to define by one or two common traits • Primates are generalized (rather than specialized) mammals. • Defined by evolutionary trends • Not all traits found in every member of the order.

6. I. Limbs & Locomotion • Tendency towards erect posture • But, primates utilize a number of types of locomotion • Bipedal • Brachiation • Knuckle walkers • Fist walkers • Limb jumpers, etc.

7. Hands & Feet • Great degree of Prehensility • Five digits on hands/feet (contra horses) • Opposable thumb • In most- divergent & partially opposable big toe • Nails on all or some digits • Highly sensitive tactile pads on digit ends

9. Question to Ponder • Why are Human Feet different?

10. II. Diet & Teeth • Lack of dietary specialization – most primates are generalized feeders eating a wide variety of foods • Therefore, primates have a generalized dentition

11. III. Senses & Brain • Vision enhanced • Olfaction reduced • Complex brain

12. Vision • All primates rely heavily on vision • Color vision in Diurnal primates. • Stereoscopic vision • Eyes in front of skull, overlapping fields of vision • Accurate 3-D vision • Increased depth perception • Point to Ponder: Why would this be an adaptive trait? (hint: think environment)

13. Stereoscopic vision

14. IV. Maturation and Learning • As placental mammals, primates have relatively long gestation periods • Also have few offspring, delayed maturation, longer lifespan than other mammals • Greater dependence on learned behavior

15. V. Behaviors • Tend to be diurnal • Increased flexibility in behavior • Tend to live in social groups • In many primate social groups, males are permanent members – unusual among mammals.

16. Arboreal Adaptation Hypothesis • Traditionally, the arboreal adaptation seen as the primary factor in primate evolution • Selected for 3-D and color vision (why?). • Grasping prehensile hands/feet to grasp • Tropical arboreal environment = varied foods

17. Visual Predation hypothesis • Alternative to the AA hypothesis • Primates may have first evolved in bushy forest undergrowth relying on insect diet • Grasping hands & vision for grabbing insects. • Tree jumping came later a means of locomotion that grasping hands allowed.

18. How to choose which hypothesis is correct? • Not necessarily mutually exclusive • Many primate features may have been developed in non-arboreal settings • Regardless, primates are primarily tree dwellers and whatever traits their ancestors had “preadapted” them for arboreal existences.

19. Geographical Distribution

20. Most primates are arboreal, living in forest or woodland areas • Some Old World primates do spend considerable time on land. • No primate, except for humans, is fully terrestrial – all spend some time in trees.

21. Point to Ponder? • What’s so great about trees?

22. Diet & Teeth • Omnivorous w/generalized dentition • Although some primates prefer some food items over others, most eat a combo of fruit, leaves, and insects. • Some do eat meat (chimps & baboons) • Some are leaf specialists (Colobine monkey)

24. Teeth • Most have 4 types of teeth • Incisors and canines: biting and cutting • Premolars and molars: crushing and grinding

25. Each Primate species has a specific dental pattern

26. Locomotion • Almost all primates are quadrapedal • Many use more than one form of locomotion • Long, flexible lumbar spine which provides greater propulsion from hind legs

27. Types of Locomotion • Vertical clinging & leaping (prosimians) • Brachiation (apes) • Semi-brachiation (combo leaping/brachiating) • Quadrapedalism • Bipedalism (us)

29. Taxonomies organized from general to more specific • All primates grouped in the Order of Primates

30. Two Suborders • Prosimii • Lemurs, Lorises, Tarsiers • Anthropoidea • Monkeys, Apes, Humans

31. Purposes of Taxonomic classification • To show evolutionary relationship • Animals grouped together or close by more closely related • Organize Diversity • Make sense of differences & similarities

32. But, system is not necessarily perfect • Studies of Orang chromosomes show it much different from African apes (and these are closer to Humans than Orangs). • Humans & Chimps most closely related (based on DNA studies) • Some researchers use a different scheme to show closeness of Chimp/Human

33. SURVEY OF LIVING PRIMATES

34. Prosimians: Lemurs & Lorises • Most primitive • Greater reliance on olfaction (long snouts) • Mark territory with scent • More laterally placed eyes • Shorter gestation & maturation • “dental comb” (projecting lower incisors & canines)

35. Lemur and Loris

36. Lemurs • Madagascar • Many different species (diversified in absence of competing primates) • Became extinct in other areas

37. Lemurs • Range in size from 5”, 2 oz. to +2’, 22 lbs • Larger lemurs are diurnal, omnivorous • Smaller lemurs are nocturnal, insectivores • Many forms are arboreal, others are more terrestrial • Some live in large social groups • Others (Indri) are monogamous pairs

38. Lorises • Similar in appearance to Lemurs • Tropical habitats (Sri Lanka, India, SE Asia, Africa) • Survived by adopting nocturnal habits • Competition avoidance with monkeys

39. Lorises • Slow, cautious climbing form of quadrupedalism • Bushbabies active vertical climbers and leapers • Almost entirely insectivorous • Diet supplemented with fruit, gum, leaves

40. L & L • Vision is stereoscopic, but less developed than anthropoids • Color vision in diurnal, but not nocturnal • Grooming claw on second toe (not fully nailed) • Longer life spans than similarly sized mammals

41. Tarsiers • Nocturnal • SE Asia • Mated pair & offspring • Diet: insects & small vertebrates they catch by leaping from branches

42. Tarsiers difficult to classify • Prosimian traits: • Small size • Grooming claws • Unfused mandible • Anthropoid traits • Lack of Rhinarium (moist nose pad) • Orbits fully enclosed by bone

43. Anthropoids (monkeys, apes, H.s) • Generally larger body • Larger brains in absolute and relative size • Increased reliance on vision • Fully forward placed eyes; bony plate back of eye socket; greater degree of color vision • Fused mandibles; less specialized dentition • Female anatomy different; longer gestation; longer maturation; increased parental care • More social interaction

44. Monkeys • ~ 70 % of all primates are monkeys • Two types: • Old World or Catarrhini (downward-facing nose) • New World • Callitrichidae • Cebidae

45. New World Monkeys • Wide flaring noses with nostrils that face outward • Almost exclusively arboreal • Prehensile tails • With one exception, diurnal • Two Groups: • Callitrichidae • Cebidae

46. Callitrichids • Small Marmosets and Tamarins

47. Marmosets and Tamarins • Most primitive monkeys • Retain claws instead of nails (used like squirrels to climb trees) • Twins rather than single births • Family groups • Mated pair • 2 males & 1 female • Males very much involved in infant care

48. Cebids • Larger than callitrichids • 30 species • Diet varies with combo of fruits & leaves • Most are quadrupedals • Spider monkeys are semibrachiators

50. Old World Monkeys