ANTH151 Lecture Notes - Lecture 3: Cautionary Tale, Sahelanthropus, Y Chromosome
1 Jun 2018
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Week 3: Primates – Origins and Distinctive Niche
• Jane Goodall
o Primatologist, ethologist and anthropologist – now working as an
environmental and animal rights activist
o Louis Leaky asked her to study Chimpanzees at Gombe Stream
National Park, Tanzania
o She was 26 and single, thus she took her mother
o Patient long-term observation led Goodall to note tool use, violence,
affiliative action by chimpanzees
o Some criticism for feeding stations (that may have caused violence)
and intervention
• Evidence for Human Evolution:
o Anatomical → vestigial organs, ‘kluges’ or adaptive compromises,
atavisms, homologies…
o Genetic → similarity in genes, defunct genes, viral insertions…
o Biochemical → same amino acids, proteins…
o Embryological → as embryos develop, show traces of evolution
o Biogeographical → animals clustered in space
o Comparative → relations among contemporary species
o Archaeological
• Cladistics → study of branches ‘tree of life’
o Key concepts:
▪ Clade
▪ Conserved traits – old traits (who we are related to)
▪ Derived traits – more recent innovations (distinctive
adaptations we have formed)
o Look at the relationship between both conserved and derived traits
Humans Among Primates:
• The order – primate
o Mostly tropical → warm climates
o Arboreal = strong grasping hands and feet; multidirectional joints in
limbs; non-slip soles and palms and flexible spine
o A shift in sensory dominance from smell to sight
o Characteristics of primates:
▪ Grasping foot with divergent big toe
▪ Nails rather than claws on the digits (may be lost)
▪ Common to have grasping hands with opposable thumbs
▪ Elongated heel
▪ Dominance of hind limbs in locomotion
▪ Eyes rotated forward and close together (stereoscopic vision)
▪ Increased brain size (especially before birth)
▪ Long gestation period (relative to body weight)
▪ Foetal growth rate is slow relative to mother’s body weight
▪ Life history prolonged
▪ Loss of one incisor and one premolar from tooth rows
• Why do primates exist?
o Three hypotheses:
▪ 1. Adaptation to arboreal life
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▪ 2. Adaptation to predation on small prey (eyes and fingers)
▪ 3. Angiosperm radiation (flowering plant diversification)
• Cladogram of Primates
o Prosimions (lemurs and lorises)
▪ Have big brains, big noses, 36 teeth and pronounced tooth
comb (purple)
o Anthropoids (tarsiers, new world and old world monkeys)
▪ Even bigger brains, reduced noses, 32 teeth and no tooth comb
o Hominidae (apes and humans)
• Primate Diversity:
o Since arising approximately 55-57 million years ago, great diversity
o From a small, nocturnal, tree-dwelling ancestor – now approx. 300
species (with subspecies, adaptive radiation)
• Cladistics:
o Clades based on shared ancestor
o Conserved traits are kept from ancestor
o Derived traits are newly evolved
o ‘Paraphyletic’ category error
• Convergent Evolution –
o When the same trait arises multiple times
o Similar innovations occur throughout species e.g. wings
o Wings have arisen at least 4 different times in animal kingdom – they
are not part of a single clade
o This can throw off cladistics analyses
• Comparative Primatology:
o Teeth and diet –
▪ Folivores cat leaves (require special adaptations)
▪ Frugivores eat fruit
▪ Faunivores eat insects and small vertebrates
▪ Gumnivores eat tree sap and resins
▪ Omnivores eat a bit of everything
o Primate locomotion –
▪ Brachiating; swinging by arms
▪ Climbing
▪ Leaping
▪ Quadrupedal walking
▪ ‘Knuckle’ walking (fist walking in orangutans)
▪ Bipedal walking
▪ Running
▪ Versatility and variation the result of arboreal origin, that is
‘living in the trees’
o Hands and feet –
▪ All are homologous structures with many similarities (e.g. toes
on human foot)
▪ Both hands and feet are often compromise structures, adapted
for both locomotion and manipulation
▪ Some primate hands specialized, such as elongated fingers for
digging insects
o Specialised hands –
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