1. Chapter 5: Primates

2. What is a Primate?
First, primates are members of the vertebrate class: Mammalia
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 Anthropoidea Lemurs, Lorises, Tarsiers
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

51. Still finding new monkeys
April 22, 2000: Conservation International announced the discovery 2 new marmoset species in the Amazon Basin of Brazil. 
Both species are squirrel size. 
They have been named Callithrix manicorensis and Callithrix acariensis. 
Since 1990, ten new monkey species have been discovered in Brazil. 

52. One family: Cercopithecidae Two subfamilies:
Cercopithecines and Colobines

53. Cercopithecines More generalized than Colobines More omnivourous
Cheek pouches to store food while foraging
Most found in Africa
Altho, a number of macaques are found in Asia

54. Colobines Leaf diet Colobus monkey exclusive to Africa
Langurs found in Asia
Probiscus in Borneo

55. Old World monkeys Variety of locomotion
Guenons, macaques, langurs: arboreal
Baboons, patas, macaques: terrestrial quadrupeds
Colobus: semibrachiation and leaping

56. Significant sexual dimorphism, esp. in terrestrial quadrupeds (baboons)
Females of several have genitalia that changes according to reproductive cycle
Estrus– hormonally induced cycle

58. Homoplasy
Evolutionary principle that explains similarities between NW & OW monkeys
Genetically distinct populations responding to similar environmental pressures.

59. NW & OW monkeys have been separated for ~ 30 million years
But, derived from same African ancestors
Perhaps they “rafted”

60. Hominoids (apes & humans)
Super-family includes:
Less apes: gibbons and siamangs
Great apes: gorillas, orangutans, chimps
Humans (family Hominidae)

61. Hominoid traits Lack of tail Larger body size (except in lesser apes)
Shortened trunk
Different musculature in shoulder joint
More complex behavior
Longer infant development & dependence
More complex brains

62. Hominoids

63. Gibbons & Siamangs Tropical SE Asia Extremely long arm limbs
Curved fingers
Reduced thumbs
Powerful shoulder muscles
Most efficient brachiator

64. Gibbons & Siamangs Monogamous pairs Lack of sexual dimorphism
Males share equally in child care
Mated pairs are very territorial

65. Orangutans Borneo & Sumatra Almost completely arboreal
Solitary animals
Mainly frugivorous
Very large
(males = 200 lbs, females = 100 lbs)

66. Gorillas Larges of living primate Knuckle walkers
Exclusively vegetarianism
Marked sexual dimorphism
Males = 400 lbs, females 200 lbs.
Family group: Silverback male & harem

67. Chimps Equatorial Africa Also knuckle walkers
Large social groups with no single,dominant male
Sexually dimorphic, but not as pronounced as gorillas and organutans
Omniverous (even will kill for meat)

68. Chimps Large social groups of up to 50 Fluid membership
Males form the core of the community, females leave, often during estrus

69. Bonobos Bonobos are another species of chimps More arboreal
Have been studies especially regarding sexual relations – including female to female
Frequent copulation and male/female bonds are core

70. It has been speculated that frequent sexual behavior serves to minimize stress between individuals