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Anthro 101: Human Biological Evolution
Lecture 8: Primate Comparative Anatomy
Prof. Kenneth Feldmeier
[email protected]
Comparative Anatomy & Behavior Assignment
• Due March 14th
• This will be a short 2 page essay about the material covered
this week and next. I will upload the question onto the
class website.
• Refers to Chapter 8 & 9, and Lecture 8 & 9 (tiny bit of 10)
• These are likely to appear on the exam!
!
Basic primate phylogeny
Anthropoidea
Apes & humans
(Hominoidea)
Old World
Monkeys
New World
Monkeys
Prosimii
Tarsiers
Lemurs, lorises
Strepsirrhines
Haplorhines
Primates
Forms of Locomotion
• Slow quadrupedal climbing
• Vertical Clinging & Leaping
• Arboreal & Terrestrial
Quadrupedalism
• Semi-brachiation
• Brachiation
• Knuckle walking
• Bipedalism
Horse Skeleton - specialized
Primate Skeleton - generalized
http://www.bristol.ac.uk/centenary/look/cabinet/monkey.html
Skeletal features to note
as you do the in-class
activity:
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Body position
Spine shape
Length & shape of trunk (torso)
Position of shoulder blade (scapula)
Limb length
Finger length (thumbs)
Length of tail
Slow quadrupedal climbing (prosimians)
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Slow lorises of South Asia
Robust muscles & limb bones
Mobile ankle, wrist, hip
Short tails
Vertical clinging and leaping - prosimians
• Vertical body
◆ Orthograde
• Push off branch with hindlimbs
• Turn midair and land vertically
again
!
• Evolved two or three different
times in prosimians
!
• Bush babies
• Sifakas
• Lemurs
Sifaka
Lets Check Out Some Lemur
Locomotion
• http://upuid-www-bbc-co-uk.tru-m.net/
programmes/p00cn9fh
!10
Intermembral Index
• humerus + radius x 100
femur + tibia
!
• hindlimbs vs. forelimb
◆
longer in the part that does the most work
!
• Bipeds & vertical clinging and leaping
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hindlimb longer than forelimb
• Quadrupeds
◆
Approx equal lengths
• Brachiators
◆
forelimbs longer than hindlimbs
Arboreal quadrupeds – monkeys
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Arboreal - run & leap
Walk on palms on top of branches
Push off with hindlimbs
Stabilize with tail (long)
Pronograde (horizontal) posture
Longer fingers & toes to grab branch
Prehensile tails in NWM
No terrestrial species in NWM
Diana Monkey
Owl Monkey
Squirrel Monkey
Monkey Time
• https://www.youtube.com/watch?
v=YZM_5LAv9m8&index=18&list=PL6A
E4226E1A528B69
!13
Semibrachiation
• New World
◆ Hands + prehensile tail
!
!
!
• Old World
◆ Hands, no tail use
Semibrachiation (New World
Monkey)
• This is a Red Howler Monkey— Check
out how it uses its Prehensile tail.
• https://www.youtube.com/watch?
v=YO2KHggo4oc&list=PL6AE4226E1A5
28B69&index=2
!15
Terrestrial quadrupeds - Old world monkeys
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Lots of time on ground, but also in trees
Pronograde (horizontal) posture
Walks on palm/toes (shorter digits)
Move limbs in limited plane
◆ (baboons, dogs)
• Rarely hang full weight from arms
• Shorter tail – not balancing
• Barrel shaped rib cage
baboon
Mandrill © Robert Young
Mandrills
• https://www.youtube.com/watch?
v=qlAzwsTRzKU&index=12&list=PL6AE
4226E1A528B69
!17
Brachiation - gibbons
• Shoulder blade on the back
rather than top of torso
◆ Full range of arm motion
• Cone-shaped rib cage
• Long, curved fingers
• Small thumbs
• Long arms
• Ball and socket wrist
• No tail
Siamang
Lets Check out a Gibbon
Brachiating
• https://www.youtube.com/watch?
v=mSLFHPd8LX0&list=PL6AE4226E1A
528B69&index=7
!19
Slow quadrumanous climbing - orangutans
• Grasp branches with hands and feet as
slowly move through trees
• Females almost totally arboreal
• males distance travel on the ground
◆ Fist walking rather than knuckles
!
• Brachiating ancestor
◆ Longer arms than legs
◆ Cone shaped torso
◆ No tail
◆ Long fingers
The Man of the Forest
(Orangoutangs)
• https://www.youtube.com/watch?
v=HgZT5Xr3vkM
!21
Knuckle-walking - chimps & gorillas
• Great apes too large to brachiate frequently
◆ Still use upper body & arms, suspend body
when they do
• Stronger wrists bones than brachiators in order
to support weight on arms
!
• Brachiating ancestors
◆ Longer arms
◆ Longer fingers
◆ No tail
◆ Scapula on back
◆ Cone shaped torso
Chimpanzee
Knuckle Walkers
• https://www.youtube.com/watch?
v=HDxA8-01cp4&index=26&list=PL6AE
4226E1A528B69
!23
Hominoids: Homininae: Hominini Bipedalism
• Unique to humans (hominins)
!
• Modifications to pelvis & feet
One leg at a time: Why don’t we fall over?
• Torque (twist and downward pull
at hip) is opposed by abductor
muscles
!
• Abductors tighten during each
stride and keep you upright
!
• Abductors attach to ilium and to
the neck femur
!
• Wider, thicker ilium and longer
neck of femur increase surface
area for muscle attachment
Reminders
!
!
• Questions about grades? Come see
me!
!26
Changes in the pelvis
Human pelvis is a bowl
◆ Supports internal organs
◆ Short and broad ilium
◆ Shorter ischium
◆ abductor muscles attach to wide
surface of ilium
◆ Maintains the center of gravity
over one foot while walking
• Chimp pelvis is longer and narrower
◆ Organs “hang” below
◆ Strong muscles on ischium
Changes in the Spine
• “S-shaped” curves in
spinal column keep
trunk centered over
pelvis
• Lumbar curve
!
• C-shaped curve in
chimps more
To walk efficiently, knees must be close to center
line of body
• Pelvis wider and shorter
• Femur slants inward from wide
pelvis
• Close-knee stance
• Centers weight for balance and
efficiency (less muscle work to
hold upright)
!
• Longer leg bones
◆
Increased stride
chimp
human
Bipedality also causes changes in the feet
• Arched foot
◆ “spring”-like shock
absorbers
◆ Return energy to the next
push
◆ Heel-toe stride
!
• Loss of opposable toe necessary
to act as a platform for body big toe in-line
!
• Stiff foot makes better platform
Changes to limbs: forelimbs
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Support the body in quadrupeds
Suspend the body in brachiators
Manipulate objects in bipeds – precision grip (vs. power grip)
Comparative anatomy of manipulation
• Apes long curved fingers &
short thumb
!
• Humans shorter fingers &
longer thumb
◆ Allows precision grip and
greater opposability of hand
◆ Bones in palm rotate more
to allow finger tips to meet
the thumb
Human hand
Changes in the skull: Foramen magnum
• Hole in skull where spinal cord and brain connect
• Position indicates body posture
• Nuchal ridge on back of skull (occipital bone) show
where muscles attach
Human skull is
balanced on top!
Brain Size
Lemur
OWM
Howler monkey (NWM) à
Features of the skull
Prognathism
Enclosed eye
Orbits
!
Dental arcade
Diastema
Canine size