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1

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

2

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

3

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

4

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

5

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

6

4 Main Characteristics

1. Locomotion
2. Sensory adaptations
3. Dietary adaptations
4. Behaviour

7

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

8

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

9

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

10

Dietary Adaptations

- Primate Teeth reflect omnivorous diet
- Lack of dietary specialization
• Not herbivores or carnivores

11

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

12

Behavioural Features

- Larger brains, especially neocortex
- Controls for higher functions
- Greater facial expressiveness
- Greater vocal repertoire

13

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

14

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??

15

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

16

The Origin of Primate Characteristics:
Visual Predation Hypothesis

"Forward facing eyes and grasping hands evolved as adaptations to hunting insects"
The flies would be moving around a lot so that’s where depth perception comes in, need to be able to grasp them; so thumbs
Why has it never been accepted?
- Not many have a diet that’s high in insets, not something that’s SO important in their diet that it would have caused this

17

The Origin of Primate Characteristics:
Angiosperm Radiation Hypothesis

"Primate characteristics evolved as adaptations to a diet of flowers, nectar, berries and seeds"
Why has it never been accepted?
- Does not explain stereoscopic vision, or why molar teeth dissimilar to molars
of known nectar eating species
- The known mammal species that have diets high in nectar don't have the same teeth

18

Diet:
Foliovores, Frugivores, Insectivores

Will favour one food over others
Some have developed specialized gastrointestinal tracts to eat mostly leaves
Foliovores – leaf-eating
- Ex. colobus monkey specialized digestive system
Frugivores – fruit-eating
- Most common
Insectivores – insect-eating
- Many strepsirhines

19

Hunting

- Some primates occasionally kill, and eat birds, amphibians, and small mammals
- Even if they hunt there's no way it counts as their diet because it’s not very important (in terms of daily caloric intake)

20

Teeth

4 kinds of teeth for varied diet:
- Incisors
- Canines
- Premolars
- Molars
**Old world Monkeys and Apes
2.1.2.3
**New Works Monkeys
2.1.3.3

21

Locomotion

- Quadrupedal
- All have long arms (longer than legs)
- Brachiation- arm swinging locomotion

22

Knuckle Walkers

- Longer arms than legs
- Chimps and gorillas

23

Vertical Clinging and Leaping

- Mostly the same length arms and legs
- Many lemurs & tarsiers

24

Brachiation

- Arm-over-arm movement
- Gibbons, siamangs
- Semi-brachiators – some NW monkeys