chapter 5 overview of living primates. chapter outline primates as mammals characteristics of...
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Chapter 5
Overview of Living Primates
Chapter Outline
Primates as Mammals Characteristics of Primates Primate Adaptations Survey of the Living Primates Endangered Primates
Primates As Mammals
There are approximately 190 species of nonhuman primates
Primates belong to:– Vertebrate class - Mammalia – Subgroup of placental mammals.
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.
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
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.
Primate Maturation
Longer periods of gestation Reduced numbers of offspring Delayed maturation Extension of the entire life span.
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.
Arboreal Hypothesis
Arboreal (tree) 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.
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.
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.
Primate Diet and Teeth
Generally omnivorous, reflected in their generalized dentition.
Most eat a combination of fruits, leaves, and insects.– Some primates kill and eat small mammals.– Some primates are dietary specialists on leaves.
Most have four types of teeth: incisors, canines, premolars and molars.
Primate Locomotion
Most primates are quadrupedal, using all four limbs in their locomotion.
Arm swinging is found among the apes.– Siamangs of southeast Asia use this exclusively.– Monkeys that use a combination of leaping and arm
swinging are termed semibrachiators. Prehensile tails, found only among the new
world monkeys, are used as an aid to locomotion.
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”
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).
Lorises
Found in tropical forests and woodlands of India, Sri Lanka, southeast Asia, and Africa.
Characteristics:– Use a climbing form of 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.
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.
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
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
New World Monkeys
Almost exclusively arboreal. Found in southern Mexico and central and
south America. Two families: Callitrichidae and Cebid
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.
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.
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.
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
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”.
Orangutans (Pogo pygmaeus)
Found in heavily forested areas of Borneo and Sumatra.
Almost completely arboreal. Mmales = 200 pounds, females = 100 pounds Pronounced sexual dimorphism. Solitary Principally frugivorous (feed-eating).
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.
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.
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.
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
Humans (Homo Sapiens)
Flexible limbs and grasping hands Omnivorous diet Cognitive abilities are the result of dramatic
increases in brain size. Bipedal
Endangered Primates
Over half of all living primates are endangered, many face immediate extinction
Most primates live in tropical rain forests that are being destroyed for their natural resources.
Some primates are hunted for their meat. Others are victims of the exotic pet trade.
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.
Conservation Efforts
Many developing countries have designated areas as national parks or reserves.
Private organizations, such as the rain forest information center in Ecuador, have set up biological reserves.
Through conservation and educational programs, primate species may have a chance at escaping extinction.
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