1. Big Trends in Human Evolution

2. General Time Frame
Hominids evolved from earlier primates, of which date from the Eocene (55- 34mya) to late Miocene (7-5mya)
Prehominid primate fossil record
Modern Homo sapiens sapiens with the hand of a female Australopithecus sediba – one of our earliest ancestors!
context to understand the subsequent evolution of the human family

3. Introduction – Human Evolution
Mosaic Evolution: Different parts evolve at different rates and at different times
With respect to human evolution:
Five key attributes
Developed at varying times along our evolutionary history
Not a step-by-step process
Did not emerge right away from apelike ancestor
Biologically & Culturally the product of many different evolutionary changes occurring at different times

4. But how did we get here? Bipedalism  7 mya
Nonhoning chewing  5.5 mya
Material Culture and Tools  2.5 mya
Speech  2.5 mya
Hunting  1 mya

5. Bipedalism One of the earliest anatomical adaptations
Upright, bipedal gait was the first hallmark feature
When: 7mya
6 areas of the body

6. Anatomical Adaptations for Bipedalism
Foot
Increase in surface area
Changes to hallux
Double-arched foot
Lower Limbs
Elongated relative to arms & trunk
Double arches help reduce fatigue fractures
Act as shock absorbers
Humans: Heel  outside of foot  ball  big toe
Non-human primates: Heel  outside of foot  middle toe
Shorter tarsals
Related to increase in weight
Increased stride
Greater energy efficiency in walking

7. Anatomical Adaptations for Bipedalism
Knee & Femur
Increase in surface area
Extension decreased
Femur - angled towards the middle of the body
Double arches help reduce fatigue fractures
Act as shock absorbers
Humans: Heel  outside of foot  ball  big toe
Non-human primates: Heel  outside of foot  middle toe
Shorter tarsals
Related to increase in weight
Increased stride
Greater energy efficiency in walking

8. Anatomical Adaptations for Bipedalism
4. Pelvis
Basin-Shaped Pelvis
Boarder, shorter blades
Muscle attachments in better mechanical position
Bipeds = 1 leg when walking
Gluteal muscles side of pelvis
Change towards a basin-shaped pelvis
Support internal organs

9. Anatomical Adaptations for Bipedalism
5. Vertebral column
S-shaped rather than C-shaped
Allows for up-right posture
Less muscular effort as body is over center of gravity
Two distinctive curves
Backward (thoracic)
Forward (lumbar)
Non-human apes
1 less Vertebra
No s-curve
Vertebrae all similar size
Human vertebrae
Larger from cervical to lumbar
More weight the lower you go

10. Morphological Changes
6. Foramen Magnum – underneath the base of the skull
Foramen magnum located inferiorly (under skull) rather than posteriorly (at the back of the head)
Allows weight of head to sit directly on spinal column
Flatter face also helps with weight distribution
Bipedal – carries its head atop its skull
Quadrupedal – carries its head on the front of the body

11. Useful Website for Human Origins