Lecture 3: Primates: Our Contemporary Relatives & The Basics of Primatology


The study of non-human primate biology & behaviour

Two Key Concepts

  1. It is non-human primates
  2. Not only behavior, but it is also the biology


Structures that are superficially similar

  • Appear similar but are not
  • Example - Wings on a bird vs Wings on a bat
  • Based on function so it is NOT an evidence of evolution

Structures that serve the same purpose but have different shapes

Example - Wings on a bird

  • Share a similar function
  • Built from different parts
  • Do not have a similar structure
  • Do not pass through similar stages during embryonic development
  • Organisms do not share a common ancestor


  • Structures possessed by 2 different organisms that arise in a similar fashion
  • Similar structure even though they have diff functions
  • Example - Man and dog are mammals, so if you break down a human arm and a dog’s front leg, you will find the same bones
  • Difference - We do not use our arms for locomotion
  • Pass through similar stages during embryonic development
  • Indicative of evolution
  • Organisms that share a common ancestor
  • May serve different functions

All Primates

  1. Kingdom Animalia
  2. Phylum Chordata
  3. Subphylum Vertebrata
  4. Class Mammalia

Order Primate

Primate Characteristics

1 - Arboreal

  • Live in trees
  • Need specific characteristics to survive
  • Ability to hang on – Prehensibility
  • Idea of sensitivity in the pads of our fingertips
  • Upright posture and indication of distance
  • Good 3D depth perception

2 - Stereoscopic Vision

Looking at the same object from different angles

3 - Binocular Vision (Forward Facing Eyes)

  • Overlapping visual fields
  • Increases visual acuity – Important to all primates
  • Reduction in olfaction/ sense of smell – Reduction in the length of our snout

4 - Color Vision

  • Increases depth perception

5 - Fovea Centralis

  • Pit in the centre of retina
  • Seen in all primates and allows to have good focusing
  • Increased ability to focus at a distance
  • Allows to have good perception
  • Important to remember these characteristics because they relate back to arborealism
  • Moving from olfaction to vision

6 - Highly developed sense of touch

7 - Enlarged, complex brain

  • Changes within the brain

8 - Retention of less specialized dentition

  • Most primates are omnivorous than other mammals
  • 4 types of teeth - Canines, Incisors, Premolars, Molars
  • Dental formula -
  • Deciduous teeth (baby teeth) miss the premolar

9 - Primate Skeleton

Skull features

  • High vaulted cranium
  • Forward shifted foramen magnum – Anterior shift of your foramen magnum (hole in the head)
  • Dogs and other carnivores have it backward facing because they walk on 4 legs
  • Reduced snout
  • Post orbital bar (enclosed eye socket) - Very important for examination
  • Protection of the eye because we are reliant on visual acuity

Retention of Clavicle (Collarbone) – Maintains the lateral positioning of your shoulder

  • Brachiation – Swinging thru trees using your arms
  • Arborealism – Ability to live in the trees

Pentadactyly (possessing 5 digits) and opposable thumb for better grip

  • Prehensibility

10 - Reproduction & Care of Young

  • Able to breed throughout the year
  • Females ovulate every month - Hidden in humans
  • Other primates give signs (mating calls) when they are ovulating
  • Mother and infant form the centre of all primate groups
  • Constant contact between the mother and the kid (monkeys and apes carry the kid on the tummy and then the back till 6 months of age)
  • Reduction in the number of offspring born at one time to a female
  • Longer period of infant dependency on the mother


Strepsirhini (Lemurs & Lorises)

  • Primitive
  • Developed olfactory
  • Rhinarium
  • Long snout
  • Dental comb
  • Grooming claw
  • Leaping & clinging
  • Found in Madagascar (Lemurs)

Infraorder - Lemuriformes


Lemuroidea (lemur)

  • Madagascar
  • Lorisoidea (Loris)
  • Africa, South & East Asia
  • Nocturnal

Haplorhini (Tarsiers, Monkeys, Apes & Humans)

Compared to strepsirhini -

  • Generally larger body size
  • Larger brain
  • Rounded skull
  • Eyes rotated to the front
  • Bony plate at back of eye orbit
  • No rhinarium – Wet fleshy pad at the end of the nose - Strepsirrhini maintain rhinariums
  • Chisel like incisors
  • Increased parental care
  • Increased maturation
  • More mutual grooming

Prosimian – Lemur, loris and a tarsier (name comes from your anklebone – Tarsal)

Anthropoid – Monkeys, apes and humans

  • Difference is the placement of a tarsier
  • Placed with advanced primates because they have some characteristics they share with all of them and that are unique amongst themselves
  • Mandible is still unfused
  • Big eyes – Cover 2/3 of their face
  • Primitive characteristics
  • Don’t have rhinarium, closed eye sockets, new world monkey’s dental formula
  • Have haplorhini characteristics, as well as strepsirrhini


Tarsiformes (Tarsiers)

Haplorrhine most like the lemur

Primitive features

  • Small body, grooming claw, large ears, unfused mandible
  • Nocturnal insectivore
  • Stable pair bonds
  • Haplorrhine features
  • No rhinarium
  • Eye sockets enclosed in bone
  • Unique features
  • Enormous eyes
  • Rotate head 180 degrees
  • Elongated tarsal bone to leap

Anthropoidea (All monkeys, apes and humans)


Platyrrhini (New World Monkey)

  • South & Central America
  • Wide range of size, diet, ecological adaptation
  • Broad flaring noses with outward nostrils (Platyrrhine - Flat nose)
  • Almost exclusively arboreal

Long prehensile tails – Important feature of the new world monkey

  • Flat nosed – Platy- flat; Rhiny- nose

Catarrhini (Old World Monkey, Apes, Humans)

  • Downward nostril


Cercopithecoidea - Old World Monkey

  • dental formula
  • Africa, South Asia
  • Downward nostrils
  • No prehensile tail – Tail used for communication, like a cat
  • Quadrupedal, mostly arboreal
  • Ischial callosity – Butt pads, swell up in females when they ovulate; signal for the guys
  • Good manual dexterity
  • Tail - Balance & communication

Hominoidea (Apes & Humans)

  • Generally larger body size
  • No tail
  • Shortened trunk
  • Changed ms of shoulder joint
  • Complex behavior
  • Enhanced cognition
  • Increased infant dependency
  • Diff between monkeys and apes – Monkeys have tails, Apes do not


Hylobatidae (Lesser Apes) Southeast Asia

  • Gibbons & Siamangs – swing thru the trees by their arms
  • Siamangs are monogamous
  • Father takes a large parental role
  • Smallest of apes
  • True Brachiators
  • Monogamous
  • Territorial - Alarm calls

Hominidae (Greater Apes and Humans)


1 - Ponginae (Asian Great Ape) Indonesia - Orangutan

  • Large sexual dimorphism
  • Frugivorous
  • Arboreal, quadrupedal on ground - "Fist Walkers"
  • Largely solitary

2 - Gorillinae (Gorillas)

  • Central Africa
  • Large sexual dimorphism
  • Terrestrial
  • Knuckle walkers
  • Shy, gentle vegetarians

3. Homininae (Chimpanzees, bonobos & humans)

Tribe -

1. Panini (Chimpanzees & Bonobos)

  • Africa
  • Knuckle walkers
  • Less sexual dimorphism – Less difference in appearance between males and females
  • Chimps – Based on a food ecology
  • Matrilinealism
  • Females hindered by kids so males take the food first
  • Cannot form solidarity with each other
  • Males are quite viscous towards females
  • Infanticide is common but the females copulate with every male so that the child is safe
  • Bonobos
  • Form coalitions and solidarity
  • Use them to protect themselves from males
  • Engage in recreational sex outside of copulation
  • Omnivorous
  • Large fluid communities
  • Complex social behavior

2. Hominini (Humans & our ancestors)

What does it mean to be human?

  • Biology
  • Habitual bipedalism – Unique human locomotion
  • Chimps do it too but it’s not their primary form of locomotion
  • Changes in our anatomy that allows us to walk like that
  • Enlarged brain relative to body size
  • Encephalization
  • Relaxed estrous (concealed ovulation)


  • Modification of environment
  • Language
  • Sexual division of labor


  1. Social groups
  2. Dominance
  3. Grooming
  4. Reproduction
  5. Mother-infant relationships

Social Groups

A major characteristic of all primates

  • One male mating system – Gorilla
  • Single dominant silver back male with a number of fertile females in return for protection for themselves and their offspring
  • Multimale/multifemale – Humans, chimpanzees and bonobos
  • In chimps, reflective of promiscuousness
  • Monogamous pairs – Gibbons and siamongs
  • Solitary – Originally believed that orangutans had solitary lifestyles


  • Most primate societies are organized into dominance hierarchies
  • Mitigates violence
  • Born in diff social hierarchies
  • Can move up or down in rank
  • Common feature seen in almost all primate groups


  • To impose order within groups
  • Establish parameters
  • Reduce physical violence
  • Rank may change
  • Learn position in hierarchy
  • Ritualized behavior – Behavior removed from its original context and sometimes exaggerated to convey information
  • Mounting & presenting
  • Staring – Common in all primates
  • Displacement – Idea of personal space
  • Dominant individual will displace the subordinate
  • Maintaining the dominance hierarchy without violence
  • When primates smile, it is considered a fear grimace


  • Functions
  • Hygiene
  • Social significance
  • Reinforce bonds


  • Sexual behavior tied to female estrous
  • Behavioral changes
  • Visual cues usually lead to copulatory opportunities
  • No fixed breeding season

Mother-Infant Relationships

  • Forms the basic social unit
  • Harlow & Harlow (1961)
  • Investigated mother’s role in infant development
  • Raised infant macaques with a surrogate mother made of either cloth or metal
  • No macaque raised without a mother achieved normal sexual behavior in adulthood

Alloparenting (Aunt behavior)

Mother chooses a trusted person to take care of the kids

  • Benefits
  • Helps the other girl to experience taking care of the kids
  • Allows mothers to go away and do stuff away from their kids
  • Can lead to adoption if the mother dies – Often the alloparent
  • Alloparent bonding
  • Common behavior in many primate species where by individuals other than the parent hold, carry, groom and generally interact with infants
  • Primate Conservation

Worldwide Depletion

  • Habitat Destruction – No more houses for primates in Sri Lanka because of the cutting down of trees
  • Hunting
  • Live Capture for Export & Local Trade


  • National Parks & Wildlife Reserves
  • CITES – Convention for the Intervention of Exotic Species
  • Education – Primates play a key role in the growing of the forest
  • Economic Alternatives
  • Breeding Colonies

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