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 A105 Human Origins and Prehistory
Lecture 7

Primate Intelligence and Culture; Primate Evolution; Why are there Hominids?

Primate Intelligence and Culture
How “smart” are primates?
Do they have culture?

                             Intelligence
What are we measuring?

How can we compare different primates, with different specializations?
 

Behaviors studied: field and laboratory experimentation
 
 

Learning and teaching: imitation?
 

Consciousness, language, tool use, culture
 

Communication
Vervet alarm calls: predator-specific, instinctual and learned components
 

Tamarins, red colobus, gibbons also may produce such calls
Limited to the present
 

Language behavior requires use of symbol, ability to time and space-shift.
 

Can primates learn language?
Controversial 
Vicki, ’50s – raised as human, speech.
 

1960s – Washoe.  Was taught sign language (ASL).  Learned over 100 signs; tried to teach other chimps.  Other ASL primates: Nim, Koko, Michael.
 
 

1970s-80s – Lana, Sherman, Austin.  Learned symbols on special keyboard.  
 

Bonobo language studies
Kanzi, Panbanisha, Matata, Tamuli, Nyota
Also use lexigram keyboards; extensive English comprehension.
 
 

Understand novel sentences
Grammar? Language?
 
 

Primate Cultures
Recall: cultural behavior is learned; passed down through learning.
Learning can occur through observation or teaching; primates don’t seem to teach much.
 

Japanese macaques: invented potato-washing behavior.  Not all groups have this behavior.
 

Chimpanzee cultural behaviors
Chimp tool and social behaviors vary between groups
Social behaviors: grooming hand clasp, leaf clipping
Tool behaviors: termite fishing, ant dipping, leaf sponge, leaf napkin, club, missile, dental pick, nut hammer, mattress (nest)
 
 
 
 

Hunting: different methods at different field sites
 

Kanzi, Panbanisha: stone toolmaking experiments

Hunting at Gombe
Prey mostly red colobus.
Opportunistic, about 25x/year.
Group hunts ~50% successful.
More often, hunts occur in more open areas: chimps wait at colobus escape points, or chase til they fall to the ground.
 

Tai hunting
More planning
All hunts are group hunts
Pincers movement; drive colobus toward waiting chimp
Hunt adult as well as infant colobus (Gombe, usually only infants); fearless
Why?  Only closed canopy available at Tai.
 
 

                                  Primate Evolution
65 million years ago (mya): ¾ of the late Mesozoic species vanished – dinosaurs, marine organisms, etc.
Paleocene (begins 65 mya): 1/3 mammalian orders appear
Why?  Confluence of environmental disasters: greenhouse warming, followed by a cooling event (droughts), K/T impact = 7 myr extinction event.
 

The First Primates
Appear shortly after flowering trees, which have many things primates today need
Filled new niches as nocturnal, arboreal animals: good vision, eat insects, fruits/flowers
Paleocene (65-55 mya):  “primatelike mammals”
Purgatorius is the earliest possible primate.
Single, rounded molar…generalized insectivore
Plesiadapiform; earliest mammal group possibly related to primates
 

Eocene (55-34 mya): earliest true primates (prosimian-like)
Two groups: Omomyoids, Adapoids
North America, Europe
Cantius, 50 mya, LCA with lemurs, lorises
Squirrel-sized, small-brained, diurnal, no postorbital closure, big snout, eyes face to side
2.1.4.3 dental formula; molar cusps rounded and broad incisors: frugivores
Postcrania lemur-like.

Another Eocene primate: Adapis, 40 mya
Similar to Cantius, but larger body, shorter snout
Eyes more frontated
Teeth like Cantius, but 2.1.3.3 dental formula
Dimorphic; brain still smaller than living lemurs
May be anthropoid LCA; however, some early possible anthropoids recently discovered.
 
 
 

Oligocene (34-23 mya): early anthropoids
Most in Africa; some in North America, Europe
Your text mentions Apidium as one possible root anthropoid.
Squirrel-size, frugivore, arboreal quadruped

Another Oligocene anthropoid: Aegyptopithecus (30 mya)
Monkey-size (15lb) with lemur-size brain
Reduced snout
Dental formula: 2.1.2.3 with even rounder molar cusps
Postorbital closure
Heavily muscled, arboreal quadruped
LCA of apes, Old World monkeys
 
 
 
 

Miocene (23-5 mya) primates: the first hominoids (apes)
See pg. 192 in your book. A few highlights:
Proconsul: very early, well-known ape
Ouranopithecus: possibly related to African apes and humans
Sivapithecus: strong resemblance to the orangutan
 

Proconsul, 15 mya
African
25 lbs
Larger incisors, smaller canines, much less snout; brain Old World monkey size
Apelike: no tail, mobile shoulder, short fingers and toes
Monkeylike: torso suggests leaping, no brachiation
 

Ouranopithecus
9-10 mya
100 lbs.
Like chimp,very robust
Brow ridge, no snout; prognathism only alveolar
Large molars, thick enamel “superfrugivore”

Sivapithecus
Turkey, Pakistan
8 mya
Many facial features strongly resemble the orangutan

Primate Evolutionary Trends
Brain size increases
Snout/bony nose decreases
Eyes become more frontated
Larger incisors, 4 to 2 premolars, molars have thick enamel, rounded, large (frugivory)
Body size increases
Locomotion: from clinging, leaping, scurrying to generalized quadrupedalism (monkeylike) to addition of suspensory behavior
 
 

Why are there hominids?
Hominids seem to appear in the late Miocene.
Cooling and drying: Messinian Crisis, Mediterranean sea dried up.
Shrinkage of tropical forests, expansion of woodlands
African apes expanded their forest adaptation
Hominids instead adapted to woodland habitats
 
 

Bipedalism: Trademark adaptation
Bipedalism is unique to humans among primates
It is habitual and obligate in humans…was it always so?
Thought to be an adaptation to drier, less forested environments, but why?
Let’s think about the possible advantages and disadvantages of bipedalism.