Ch 6 Overview of the Primates Flashcards
Anthropomorphism
“The attribution of human characteristics or behaviour to a god, animal, or object “
- In science, anthropomorphism equated with a lack of objectivity
- Has been really influential in discrediting some arguments
- Do not assume animals share any of the same mental, social, and emotional capacities of humans; rely on strictly observable evidence
Why Study Primates?
- Helps compare ourselves with our closest living relatives
• Can use their behaviour to make suggestions about our behaviour
• Can use it to make hypothesis - To compare anatomy and behaviour
- To explain selective or random factors impact on behavioural and physiological systems
Defining a Primate:
Class, similarities
Class: Mammalia - Member of the placental subcategory (not egg-laying or marsupial subcategories) Other Placental Mammals Similarities include • Body hair, mammary glands, heterodonty • Increased brain size, capacity for learning, behavioural flexibility • Long gestation period, live birth • Thermoregulation
Primates as Generalists
Makes the group hard to define
- Big reason for our and their success
- Lack specialized features
• No single characteristic that distinguishes them from other orders of mammals
General Characteristics: #, location, size range
Number - 300 primate species identified: Living and non-living Location - Most in tropics, sub-tropics Size - Great range in size • Pygmy Mouse Lemur 30g • Gorilla 200kg • Gigantopithecus blacki (extinct) maybe 600kg
4 Main Characteristics
- Locomotion
- Sensory adaptations
- Dietary adaptations
- Behaviour
Locomotory Features
- Generalized skeletal structure: upright, flexible shoulder joints
- Grasping hands
- Opposable thumbs
- Grasping feet (opposable big toe)
- Nails instead of claws
- Flattened nail with tactile pad
Sensory Adaptations
- Colour vision (except nocturnal primates)
- Depth perception-
• Forward facing eyes
• Overlapping fields of view
• Decreased reliance on smell - Reduction in snout size (rostrum) and olfactory areas of brain
Sensory Adaptations:
Bony orbit in prosimians vs. monkeys, apes and humans
- Enclosed bony orbit
• Evolved for protection - Post-orbital bar in prosimians (not monkeys and apes)
- Post-orbital plate or cup in monkeys, apes, humans
Dietary Adaptations
- Primate Teeth reflect omnivorous diet
- Lack of dietary specialization
• Not herbivores or carnivores
Dietary Adaptations:
Teeth
Diphyodont – two sets of teeth, ‘baby’ and ‘adult’
Heterodont – different kinds of teeth (incisors, canines, premolars, molars)
- Primates have fewer teeth than other mammals
Behavioural Features
- Larger brains, especially neocortex
- Controls for higher functions
- Greater facial expressiveness
- Greater vocal repertoire
Behavioural Features:
Reproduction and Nurturing
- Longer gestation period & lower reproductive rate
- K-selection
• Fewer offspring
• Single births the norm
• Greater investment of parental care to improve survival odds - Long period of offspring dependency
Middle Ear
Petrosal bulla
- Bony casing of a bony plate in middle ear
- Separates middle ear region from interior of skull
- Can be detected in fossil primates
- Maybe this is the trait that will always distinguish other mammals from primates??
The Origin of Primate Characteristics:
Arboreal Hypothesis
“Forward-facing eyes, grasping hands, nails instead of claws all evolved as adaptation to an arboreal way of life”
Why has it never been accepted?
• There are other mammals that are very well adapted to living in trees (squirrels) that do not possess similar traits to us
