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Chapter 7: The Living Primates (Primate Adaptations (Small body size,…
Chapter 7: The Living Primates
Primates
Shared Physical Traits
Arboreal
Prehensile hands and feet, opposable thumb/fine motor control skills
Flexible arm movement (collarbone), specific upper and lower limb bones (allows for wrist/ankle movement)
Omnivorous diet, unspecialized molars/premolars, specialized incisors/canines
Forward facing eyes, stereoscopic vision (3D) colour vision
Reproduction
Male: Penis unattached to abdomen
Females: two nipples on chest, 1 to few offspring
Offspring tend to be larger, longer to reach sexual maturity
Social Features
Social learning starts with mother infant bond, infants raised by group
Offspring dependent for long periods of time
Lack of social relationship = poor social skills
Playing to learn, practice for physical skills, learning social skills
Primates learn from others through imitation, independent learning and deliberate teaching
Referential Communication:
Sound association to object or event
Symbolic Communication:
meaning without referent, meaning is arbitrary
Primate Communication: Closed system(calls and sounds cannot be reorganized) humans have open system
Capacity for language: many apes have capacity, limited by lack of grammar and discourse
Primate Classification
Prosimians
Premonkeys
Mammal Traits
Longer snouts
Mobile ears
Olfactory
Primate traits
Grasping hands
Stereoscopic Vision
Lemurs
Strepsirhines (wet nose = better sense of smell)
Quadrupeds
Some vertical clinging and leaping
Females dominate social groups
Not sexually dinmorphic
Lorises
Strepsirhine
Nocturnal & Arboreal
Vertical leaping
Quadruped
Female-led related groups
Males in solitary, newborns 'parked'
Tarsiers
Haplorhines (dry noses, make classification controversial)
Nocturnal, enormous eyes
Arboreal, long ankle bones for leaping
Insectivores, or eat small mammals
Antrhopoid Traits: reduced dependency on smell, eyes in bony orbits
Anthropoids
Humans, apes, monkeys diverged 40 000 years ago
Rounded braincase, reduced, non-mobile ears, relatively small flat faces, more fully formed placenta, highly dextrous hands
Platyrrhines: New World Monkeys
Nose shape, flat
Three premolars
Prehensile tail in some
Arboreal lifestyle
Dentition 2.1.3.3
Catarrhines: Cercopithecoids
Old World Monkey
Native to Africa and Asia
Various habitats/environments - arboreal, tropics, forest, savannah
Colobine Monkeys, Arboreal
Vegetation diet, complex stomach with bacteria
Flexible group size, male dominated
Few offspring, dependency 4-6 years, infanticide known
Terrestrial groups
Sexual Dimorphism
Social groups of female core = troop
Occupy wide range of habitats
Few offspring, longer dependency, infanticide known
Hominoids
Apes and humans , Hylobates, pongids, hominins
Larger brains, greater flexibility, longer limbs, short broad trunk, no tail
Dentition: flat and rounded , Y-5 pattern, canine diastema
Hylobates
Brachiators , swing through trees, long arms and fingers, small body size and weight
Frugivores; some leaves
Small family units, little sexual dimorphism, highly territorial
Pongids: Orangutans
Arboreal (slow, heaviest of all arboreal)
frugivores, easier to live alone to find food, females with young are the only ones in groups, avoid predation by living alone
Sexually dimorphic
Gorillas
Largest of the surviving apes, quadrupeds, knuckle walkers
Partially arboreal, eat and sleep in trees; mostly vegetables, leaves, roots, stems & fruit
Social groups are moderately sized, dominant male = protector. flexible membership
Chimpanzees and Bonobos
Chimpanzees: larger, sexually dimorphic. Fluid, leave and join groups
Bonobos: smaller, no sexual dimorphism. Stable, female centred groups, members stay
Arboreal and terrestrial, quadrupedal and bipedal
Frugivore, with some meat
Highly social, large group
Primate Adaptations
Small body size, nocturnal, arboreal, frugivore
Large body size, diurnal, terrestrial, vegetarian
Relative brain size: larger primates normally have larger brains, frugivores have larger brains than vegetarians
Group Size: safer in smaller numbers when feeding at night, safer in larger numbers when feeding during the day
Sexual dimorphism: selection for increased reproduction: shorter/slighter statures, wider pelvises, nutrients go towards having offspring, rather than being tall and broad
Hominins: Homo sapiens
Bipedalism, dish-shaped pelvis, straight lower limbs, feet not prehensile (arch to aid walking), hands dextrous with thumb shape, no large teeth and claws
Brain: centered over spine, large cerebral cortex = speech and higher mental functions
Dentition: reflects omnivorous diet, incisors and canines similar, no space between teeth (diastema)
Language: Brocas area is larger, lowering of larynx during maturation allows for speech
Models for Understanding Hominin Behaviour
1) Behavioural Ecology: living primate behaviour as model
Reconstruct hominin biologyand environment
Hominin social environment, experimental observations
Field observations: more complete picture of behaviour
2) Ethnographic Analogy
Non-western foraging societies = model for early hominin culture
Limitations: Assume similar patterns of behaviour in similar environments, groups not isolated
All cultural groups have their own qualities, not always reflective of a universal pattern