Chapters 4 to 6

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4 Mar 2011
Chapter 4 – Monkeys, Apes and Humans
Primate Order
-primates share number of ancestral traits with other mammals
-mammals are intelligent animals
-young are born in womb
-young are nourished by mothers with milk thus getting the name of Mammalia
-young learn to survive as adults
-mammals also active animals by body temperature and respiratory system
-joints for growth
two classificatory systems exist for dividing primate order
Older system
1. Prosimii – before monkeys, night time dwellers and tree dwelling
2. Anthropoidea – monkeys, apes and humans
a.Platyrrhini (New World Monkeys)
b. Catarrhini - Cercopithecoidea (Old World Monkeys) and
Hominoidea (apes)
1. Poginae (orangutan)
2. Hominini (African apes and humans)
Primate Characteristics
Derived traits: traits evolved and changed from characteristics in the common ancestor
Primate Brain
-tend to be large and heavy in proportion
-Why increased size?
oDue to extinction of dinosaurs, survival at night was gone and more
activity in the daylight caused for better vision which was in the brain
oAlso the use of the hand increased causing better coordination with the
Primary Sense Organs
-Catching insects on trees and able to jump and land safely needed good sense and
-Binocular vision: vision increased depth perception from two eyes set next to each
other allowing visual fields to overlap
-Stereoscopic vision: complete 3D vision plus visual connections from each eyes
to both sides of brain
-Sense of smell – haplorhines have least developed sense of smell
-Sense of touch and grasping mechanism
Primate Dentition
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-incisors , canine , premolars, molars – new world monkeys 2-1-3-3
-humans and old world monkeys and apes share a 2-1-2-3 dental formula
Primate Skeleton
-Cranium – brain case of the skull tends to be high and vaulted protecting the brain
-Foramen magnum – large opening in the skull through which the spinal cord
passes and connects to the brain
oSpine and brain joins in centre of its base making upright posture
oOthers do not have foramen magnum as forward
-Clavicle: collarbone prevents arm from collapsing inward when brought across
the front of the body
-Brachiate: use their arms to swing from branch to branch and hang beneath
oBest example of brachiates are the Hylobatidae
-Pentadactyly: Possessing 5 fingers and toes for good prehensile (grasping)
Reproduction and Care of Young
-Males ready to engage in sexual activity when females are in estrus (ovulation)
-Among some primates give birth to a few offspring at a time
-Natural selection favors single births as tree dwellers hard to carry more than one
while swinging
-Single births must have longer periods of motherhood
Modern Primates
-most primitive primates (lemurs)
Divided into three infraorders
-Tarsii, Platyrrhini and Catarrhini
-kitten sized arboreal creatures are huge in proportion
-ability to turn heads 180 degrees
Social Behavior of Primates
-Females are more dominant for Bonobos than for chimpanzees
-Usually the size of the animal is higher rank but sometimes mother skills
considered higher rank
Individual Interaction
-usually grooming to clean off parasites and also to strengthen social bonds
-grooming often conveys expression of submission, friendship or appeasement
Sexual Behavior
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