Human Evolution Nyu Exam 2

Front 1

Primate Characteristic Symplesiomorphies (Primitive; Ancestral traits)

Back 1

• Pendactyly – 5 fingers
• Two Lower arm bones (radius and ulna
• Clavicle – shoulder bone
• Generalized body plan. (all have similar sturucture)

Front 2

Primate Characteristics Synapomorphies (derived trait)

Back 2

• Reduced olfaction (short snouts, fewer whiskers, smaller olfactory bulb)
• Emphasis on Vision (forward facing eyes-Stereoscopic vision)
• Post Orbital bar – not only animals with bar
• Tendency for vertical posture
• Grasping hands and feet
• Nails (vs claws) (exceptions are some strepserines – some tamerines have claw like nails. Tarsiers have grooming claws
• 1st digit opposability
• Petrosal bulla (inner ear bones housed in petrous portion of temporal bone) NO OTHER ANIMAL HAS THIS
• Increased flexion to skull base
• Tendency for large brains
• Slow life history
o Fewer young
o More parental investment
o Longer development period
o Later reproduction
o Longer lifespan

Front 3

Post Orbital bar on Streps and haps

Back 3

Streps have bar
Haps have closure
Tarsiers have partial post orbital closure

Front 4

Strep/hap differences

Back 4

• Rhinarium in streps separates nose/mouth in haps
• Unfused frontal and mandible in streps
• Tapetum Lucidem (eye shine) in streps (Haps lack Tapetum Lucidem unless they are nocturnal)
• Strepserhines have second claw digit called toilet claw
• Streps have a tooth comb as derived in streps

Front 5

Tarsiers/Anthrpoid differences

Back 5

• Tarsiers are haps that retain grooming (toilet) claws and unfused mandibles
• Frontal bones are fused
• Orbit is partially closed

Front 6

Platyrrhines/Catarrhine differences

Back 6

• Rhinarium in streps; separate nose/mouth in haps
• Unfused frontal and mandible in streps
• Tapetum lucidem (eye shine) in streps
• Haps lack tapetum lucidem
• Nocturnal haps have big eyes
• Retention of claw on 2nd digit in streps – grooming/toilet claw
• Tooth comb (projecting incisors and canine) as derived in streps
• Tarsiers are haps that retain grooming claws and unfused mandibles
• Orbit is partially closed in tarsiers
• Frontal bones are fused
• Broad, laterally-facing nostrils in plats; narrow and down in cats
• Plats retain 3 premolars; cats have just 2 premolars
• Dental formula (1/4 of the mouth):
2 incisors, 1 canine, 3 premolars, 3 molars (2.1.3.3)
2.1.2.3 in cats

Front 7

Cercopithecoid-Hominoid differences

Back 7

• Cercos have bilophodont molars
– Crests between cusps
• Apes have bunodont molars
– Rounded cusps
– Y-5 cusp pattern
• Cercos possess tails
• Apes lack tails (coccyx)
• Long arms, extensive shoulder mobility in apes
• Upright trunk posture in apes
– Dorsally-located scapulae
– Wide rather than deep chest
• Shorter, less flexible lower back in apes
– Fewer and shorter lumbar vertebrae

Front 8

Why are primates social? Name benefits...

Back 8

o Anti predation strategies
• Increased vigilance
• Cooperative defense “mobbing
o Alarm calls
o Dilution effect (so many individuals that you are less likely to get eaten
o “selfish herd” (don’t have to outrun predator… just the slowest in group)
o Predator confusion

o Foraging: finding and accessing food.
• Defense or takeover food patches and territory
• Cooperation in hunting
• More eyes to find food and more efficient foraging

o Social interaction
• Access to mates
• Assistance in child rearing
• Increased learning opportunities
• Information sharing
• Cooperation coalitions
• Presence of males often means protection for predators

Front 9

What are the costs of being social?

Back 9

Predation – easier to spot

Limited resources
More resources necessary
Increased competition within group
Increased conspicuousness
Larger territory for nesting sites, food, water, etc

Increased risk of disease
Social conflict
Competition for mates
Exposure to aggression
Infanticide (present in males) - highest cause of infant mortality in mountain gorillas- observed in 17 species (12 genera) of primates.