An Overview of the Primates

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Chapter 6

• An Overview of the Primates

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Chapter Outline

• Characteristics of Primates
• Primate Adaptations
• Primate Classification
• Survey of the Living Primates
• Endangered Primates

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Primates As Mammals

• There are approximately 190 species of nonhuman
  primates
• Primates belong to
• Vertebrate class - Mammalia
• Subgroup of placental mammals.

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Characteristics of Primates

• Fur (body hair)
• Long gestation followed by live birth
• Homeothermy, the ability to maintain a constant
  body temperature
• Increased brain size
• Capacity for learning and behavioral flexibility.

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Primate Limbs

• A tendency towards erect posture.
• Hands and feet possess grasping ability.
• Features of the hands and feet
• 5 digits on hand and feet
• Opposable thumb
• partially opposable great toe
• Tactile pads enriched with sensory nerve fibers
  at the ends of digits

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Primate Senses and the Brain

• Color vision is a characteristic of all diurnal
  primates, nocturnal primates lack color vision.
• Depth perception is made possible by eyes
  positioned forward on the front of the face.
• Decreased reliance on the sense of smell.
• The brain has expanded in size and become
  increasingly complex.

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Binocular Vision in Primates
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Primate Maturation

• Longer periods of gestation
• Reduced numbers of offspring
• Delayed maturation
• Extension of the entire life span.

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Primate Learning and Behavior

• Have a greater dependence on flexible, learned
  behavior.
• Tend to live in social groups.
• Males are permanent members of many primate
  social groups, a situation unusual among mammals.

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Arboreal Hypothesis

• Arboreal living was the most important factor in
  the evolution of primates.
• Prehensile hand is adapted to climbing in the
  trees.
• A variety of foods led to the omnivorous diet and
  generalized dentition.

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Visual Predation Hypothesis

• Primates may have first adapted to shrubby forest
  undergrowth and the lowest tiers of the forest
  canopy.
• Forward facing eyes enabled primates to judge
  distance when grabbing for insects.
• Flowering plants may have influenced primate
  evolution.

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Primate Habitats

• Most live in tropical or semitropical areas of
  the new and old worlds.
• Most are arboreal, living in forest or woodland
  habitats.
• No nonhuman primate is adapted to a fully
  terrestrial environment all spend some time in
  the trees.

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Primate Diet and Teeth

• Generally omnivorous, reflected in their
  generalized dentition.
• Most eat a combination of fruits, leaves, and
  insects.
• Most have four types of teeth incisors, canines,
  premolars and molars.

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Primate Locomotion

• Most are quadrupedal, using all four limbs in
  their locomotion.
• Arm swinging is found among the apes.
• Prehensile tails, found only among the new world
  monkeys, are used as an aid to locomotion.

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Alternative Classifications of Great Apes and
Humans
Revised classification (more evolutionarily accurate) Traditional classification
Great apesseparate family (Pongidae) Orangutan Gorilla Chimpanzee Bonobo One family only (Hominidae), including all large-bodied apes and humans more detailed distinctions made at lower taxonomic categories
Humansseparate family (Hominidae)
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Prosimians

• The most primitive of the primates.
• Characteristics
• Reliance on olfaction
• Laterally placed eyes
• Shorter gestation and maturation periods
• Dental specialization called the "dental comb

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Lemurs

• Found on the island of Madagascar and other
  islands off the coast of Africa.
• Extinct elsewhere in the world.
• Characteristics
• Larger lemurs are diurnal and eat vegetable
  foods fruit, leaves, buds, and bark.
• Smaller lemurs are nocturnal and insectivorous
  (insect -feeding).

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Lorises

• Found in tropical forests and woodlands of India,
  Sri Lanka, southeast Asia, and Africa.
• Characteristics
• Use a climbing quadrupedalism.
• Some are insectivorous others supplement their
  diet with fruit, leaves, gums, and slugs.
• Females frequently form associations for foraging
  or in sharing the same sleeping nest.

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Tarsiers

• Small nocturnal primates found on the islands of
  southeast Asia.
• Eat insects and small vertebrates which they
  catch by leaping from branches.
• Basic social pattern appears to be a family unit
  consisting of a mated pair and their offspring.

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Anthropoids (Monkeys, Apes and Humans)

• Common traits
• Larger brain and body size
• Reduced reliance on the sense of smell
• Greater degree of color vision
• Bony plate at the back of the eye socket
• Different female reproductive anatomy
• Longer gestation and maturation periods
• Fused mandible

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Monkeys

• Represent about 70 of all primate species.
• Divided into two groups separated by geography
  and several million years of evolutionary
  history
• New world monkeys
• Old world monkeys

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New World Monkeys

• Almost exclusively arboreal.
• Found in southern Mexico and central and south
  America.
• Two families Callitrichidae and Cebid

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New World Monkeys Callitrichidae

• Give birth to twins
• Live in families composed of a mated pair or a
  female and two adult males, plus the offspring.
• Males are involved with infant care.

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New World Monkeys Cebid

• Possess prehensile tails.
• Most live in groups of both sexes and all ages.
• Others live as monogamous pairs with subadult
  offspring.

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Old World Monkeys

• Habitats range from tropical forests to semiarid
  desert to snow-covered areas in Japan and china.
• Characteristics
• Most quadrupedal and arboreal
• All belong to the Cercopithecidae family.
• Divided into subfamilies, the cercopithecines and
  the colobines.

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Hominoids(Apes and Humans)

• Characteristics distinguishing hominoids from
  monkeys
• Larger body size
• Absence of a tail
• Shortened trunk
• More complex behavior
• More complex brain
• Increased period of infant development and
  dependency

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Gibbons and Siamangs

• Found in the tropical areas of southeast Asia.
• Adaptations for brachiation may be related to
  feeding while hanging from branches.
• Diet is largely fruit with leaves, flowers, and
  insects.
• Basic social unit is a monogamous pair and their
  offspring.
• Males and females delineate their territories
  with whoops and songs.

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Orangutans (Pogo pygmaeus)

• Found in heavily forested areas of Borneo and
  Sumatra.
• Almost completely arboreal.
• males 200 lbs, females 100 lbs
• Pronounced sexual dimorphism.
• Solitary
• Principally frugivorous (feed-eating).

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Gorillas (Gorilla Gorilla)

• Largest of the living primates.
• Confined to forested regions of central Africa.
• Males can weigh up to 400 pounds, females 200
  pounds.
• Primarily terrestrial, using a posture called
  knuckle walking.
• Groups consist of one large silverback male, a
  few adult females, and their subadult offspring.

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Chimpanzees (Pan Troglodytes)

• Found in equatorial Africa.
• Anatomically similar to gorillas particularly in
  limb proportions and upper-body shape.
• Locomotion includes knuckle-walking on the ground
  and brachiation in the trees.
• Eat a variety of plant and animal foods.
• Large communities of as many as 50 individuals.

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Bonobos (Pan paniscus)

• Only found in an area south of the Zaire river.
• Population is believed to only number a few
  thousand individuals.
• Exploit the same foods as chimps, including
  occasional small mammals.
• Male-female bonds constitute the societal core.
• Sexuality includes frequent copulations
  throughout the female's estrous cycle.

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Humans (Homo Sapiens)

• The only living species in the family Hominidae.
• Human teeth are typical primate teeth.
• Dependence on vision for orientation to the world

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Humans (Homo Sapiens)

• Flexible limbs and grasping hands
• Omnivorous diet
• Cognitive abilities are the result of dramatic
  increases in brain size.
• Bipedal

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Endangered Primates

• Over half of all living primates are endangered,
  many face immediate extinction.
• Three reasons
• Habitat destruction
• Hunting for food
• Live capture for export or local trade

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Hunting of Primates

• In West Africa the most serious problem is
  hunting to feed the growing human population.
• Estimated that thousands of primates, are killed
  and sold for meat every year.
• Primates are also killed for commercial products.

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Quick Quiz
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• 1. Which of the following is NOT a primate
  characteristic?
• stereoscopic vision
• highly developed sense of smell
• orthograde or upright posture
• prehensility

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Answer b

• A highly developed sense of smell is NOT a
  primate characteristic.

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• 2. Binocular vision in primates contributes to
• color vision.
• lateral vision.
• panoramic vision.
• stereoscopic vision.

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Answer d

• Binocular vision in primates contributes to
  stereoscopic vision.

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• 3. Which of the following is NOT true of
  tarsiers?
• They are nocturnal.
• They are insectivorous.
• They live in groups of 10-12 individuals.
• They can rotate their heads almost 180 degrees.

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Answer c

• Tarsiers do not live in groups of 10-12
  individuals.

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• 4. The _________________ is the largest
  living primate.

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Answer gorilla

• The gorilla is the largest living primate.

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• 5. Which of the following is NOT a reason that
  nonhuman primates are endangered?
• habitat destruction for logging, mining, and
  agricultural land
• hunting for food
• live capture for either the exotic pet trade or
  biomedical research
• establishment of biological reserves

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Answer d

• The establishment of biological reserves is NOT a
  reason that nonhuman primates are endangered.