Chapter 6 - Nonhuman Primates

Primitive mammal traits that primates and humans share

• Thermoregulation (warm blooded)

• tetrapod/quadrupedal body plan ( four limbs)

• different life stages

  • period of growth and developmental changes

  • infancy, juvenile and adulthood

• Dichromatism (two colour vision)

• heterodont dentition (four types of teeth)

taxonomic classification of primates (and traits associated with each taxa)

Kingdom - animalia

phylum - chordata

subphylum - vertebrata

class - mammalia

infraclass - eutheria

superorder - archonta

Order - Primates

traits of Phylum: chordata

• notochord provides support and flexibility

• bilateral symmetry

traits of subphylum: vertebrata

• vertebral column

• presence of cranium

traits of class: Mammalia

• mammary glands

• hair

• presence of 3 ear ossicles (bones)

traits of infraclass: Eutheria

• greater placental development

• live birth (don’t lay eggs)

superorder: Archonta

includes:

• Plesiadapiformes (extinct “primate-like” mammals or “stem primates”)

• Scadentia (tree shrews)

• dermoptera (flying lemurs)

• primates

Derived traits shared by all primates

• Opposable thumbs

• finger nails (not claws) and tactile pads

• post-orbital bar (eye socket bone)

• stereoscopic (3D) vision

• relatively big brains

shared derived traits and primitive traits of Lorises and lemurs

shared derived traits

• toothcomb

primitive traits

• wet nosed - rhinarium

• grooming claw

• mostly nocturnal

• tapetum lucidum (eyeshine)

Strepsirrhines unique teeth

they have a Dental comb

• combined front teeth used for grooming and scraping sap from trees

• derived trait of strepsirrhines

Which of these have a rhinarium and How to tell if an animal has a Rhinarium

A and D - strepsirrhines because they have a rhinarium

• no hair

• splits upper lip

E - Tarsier (Haplorhin) - no rhinarium present

shared derived traits of haplorhini

shared derived traits

• loss of rhinarium - flatter noses

• loss of tapetum lucidum - no eyeshine

• trchromatism - 3 colour vision

• post-orbital enclosure

Primitive and derived Traits of Haplorhini: Tarsiers

• Longest evolutionary history

Primitive Traits

• nocturnal

• retained grooming claw

• lack of toothcomb

Derived Traits

• Dry nosed (no rhinarium)

  • no hair on nose

  • doesn’t split lip

Haplorhini: platyrrhini and their traits

• New world (western hemisphere) monkeys

• Single clade: Ceboidea

• Derived traits:

  • dry nosed - flat, wide, and turned outward

    • platy = flat, Rhine = nose

  • mostly diurnal - polymorphic dichromatic or trichromatic vision

  • prehensile tail in some (no other primates have this)

Haplorhini: Catarrhini and their traits

• characterized by dry, downward-pointing noses and 2-1-2-3 dental formula

• split into 2 superfamilies

  • Cercopithecoidea (Old world monkeys)

  • Hominoidea (Apes)

How do Apes and Old Wold Monkeys differ (traits)

• based on shared derived traits

  • apes don’t have a tail

  • apes have a distinct “Y5” molar shape

Sub-groups and siffuxes

Superfamily: -oidea

Family: -idae

Subfamily: -inae

Tribe: -ini

How did monkeys get from Africa to south america

floated and drifted through the ocean through rafts

• monkeys living in trees, they break trees into the river, basically creating a raft for them to float on

  • which is why platyrrhini are represented as a single clade

Clades of Hominoidea

• Family Hominidae - “Great” Apes

• Family Hylobatidae - “Lesse” Apes

• Subfamilies - Homininae (African ape clade), and Ponginae (Orangutans)

• Tribes - Hominini (humans and chimps) and gorillini (gorrilas)

• subtribe - Hominina (Humans) and panina (chimps and bonobos)

What kind of body plan for primates have

• quadrupedal body plan

6 different ways of locomotion of primates

• Quadrupedalism (most common) - two types are arboreal and terrestrial

  • leaping using hind limbs

  • ex. baboon and howler monkeys

• Vertical clinging and leaping - body is propelled from one branch to another using hindlimbs

  • ex. Tarsier and lemur

• slow climbing - only one limb is moved at a time

  • ex. Orangutan and Lorin

• brachiaton - hand-over-hand movement in trees

  • ex. gibbon, orangutan, and spider monkey

• knuckle walking - quadrupedal movement using knucles and sometimes standing up

  • ex/ chimp and gorilla

• bipedalism - upright walking on hindlimbs

  • ex. humans

Skeletal features of Primates (teeth and snout)

Shortened snout

• reduced sense of smell and increased vision

• also have reduced number of teeth compared to other animals

Heterodont detition - incisors, canines, premolars, and molars

• different types of teeth for eating a variety of foods and process food efficiently

  • generalizaed mammalian trait

Mammalian Dentition and the 2 types

Mammals have more complex teeth than reptiles or fish

• Homodont - all teeth similar in form

  • sharp and replaced throughout life

  • ex. sharks, crocodiles, etc.

• Heterodont - different types of teeth present

  • some specialized for chewing

  • ex. most mammals

Diphyodont dentition - One set of deciduous (baby or milk) teeth that are replaced by adult teeth as mammals mature

4 types of mammalian teeth

• Incisors - cutting teeth in the front of the jaw

• Canines - long sharp “dog” teeth

  • for communication and biting prey

• Premolars - more flattened teeth

• Molars - flat chewing teeth

Number and patterns of teeth are distinctive for different mammals

Eutherian Dental formula

3 incisors, 1 canine, 4 premolars, and 3 molars

• per side (double to get total teeth)

Formula

(incisors, canines, premolars, molars) TOP / (incisors, canines, premolars, molars) BOTTOM

What is the dental formula for humans

2-1-2-3

Specialization in primate teeth

• Insect-eating promision

• Leaf-eating lemur (Indri) - many crests for mashing up leaves

• Fruit and leaf eating ape (Hylobates) - incisors to bite into fruit

• Fruit-eating monkey (cercocebus) - incisors and crests

Diet and digestive system of primates

• lots of variation between primate species in deit

• most primates are generalists - exploit a wide range of foods sources

• types of food a primate species exploits depends on size and behaviour

• Larger animals will be more likely to eat plants and leaves

  • because they are more easily resourced

who has the largest brains (for their size) out of fish, mammals, birds, reptiles, and primates

from smallest to largest

Reptiles, Fish, birds, other mammals, and primates

Characteristics relating to brain size of primates

• Advanced ability to learn

  • many examples of primate culture

  • experimental models of apes learning language

• Advanced social structure

  • long term mother child bonding

  • ability of small groups to collaborate to gain power within larger group

Two theories of Primate Origins

• Arboreal theory

  • adapting to living trees is what caused the observable traits primates have

  • stereoscopic vision (less reliance on smell), grasping hands and feet, good eye-hand coordination, and a large brain become advantageous in trees

• Visual predation theory

  • binocular vision, good grasping capabilities, and highly refined eye-hand coordination are adaptations for insect hunting in low branches

behaviour

• anything organisms do that involves action in response to internal or external stimuli

• response of an individual, group, or species to its environment

• responses may not be deliberate (intentional) and aren’t necessarily result of conscious decision making

Behavioural ecology

• focuses on the relationship between behaviours, natural environment, and biological traits of the species

• behaviours have evolved through the operation of natural selection:

  • behaviours are influenced by genes and are subject to natural selection the same way physical characteristics are

  • but individuals also have agency and can talk and decide about behaviour given any situation

evolution of behaviour

• behaviour constitutes a phenotype

• individuals whose behavioural phenotypes increase reproductive fitness will pass on their genes at a faster rate

• genes do not code for specific behaviours (ex. aggression, cooperation, etc.)

• species vary in their limits and potentials for learning and behavioural flexibility, set by genetic factors (Nature vs. Nurture)

• Natural selection acts on genetic factors shaped by ecological setting of past and present

Is human behaviour different from primate behaviour?

No, human behaviour is primate behaviour

• our behaviour is not special from primates

• primates are social animals

Primate Social Structure

• Primates are among the most social of animals

  • social behaviour is one of the major topics in primate research

  • broad subject that includes all aspects of behaviour

Why be social? (group living)

• competition

• Costs of competition are offset by the benefits of predator protection and resource sharing provided by associating with others

• group living evolved as an adaptive response to a number of ecological variables

Primate social groups

• Primates often live in social groups with complex social orders

  • One-male, multi-female groups - one male units, able to join with others if food is plentiful, can form large stable bachelor groups

    • ex. baboons, gorrilas, howlers

  • Matrilines - consist of a female, her daughters, and their offspring

    • ex. macaques

  • pair bonds

    • not very permanent

    • ex. humans and gibbons

  • multi-male, multi-female groups

    • ex. bonobos

Domiannce hierarchies (in primate social behaviour)

• primate societies that impose order and establish parameters of individual behaviour

• higher-ranking animals have greater access to preferred food items and mating partners than lower ranking individuals

• sometimes called “pecking orders” that change throughout one’s life and are learned

Factors that influence dominance status

• Sex

• Age

• Aggression

• Intelligence

• Time in the group

• motivation

• mother’s social position

Communication (in primate social behaviour)

any act that conveys info to another individual

• goal is to stimulate a change in behaviour in the recipient

• may be caused by involuntary processes or a secondary consequence of an intentional action