L12.1 Fossil evidence for changes in human locomotion

Question 1

Definition: Evolution

Fossilisation

(what is fossilisation dependent on)

Answer 1

• Evolution = change over time, (fossil records provide strongest evidence)
• Fossilisation = conversion of organic material into minerals
  
  • Dependent on:
    
    • How & where animals lived
    • Anatomy
    • How they died
    • How quickly buried
    • Probability of erosion & being found

Question 2

Chain of human evolution

Answer 2

• *7mya 1st fossil record for human evolution
• Australopiths (Afarensis & Africanus) → early homo → Homo erectus (Homo ergaster) → Archaic Homo → Neanderthalis → Modern Humans

Question 3

Progression: Foramen magnum

Facial prognathism

Size of skull

Answer 3

• Foramen Magnum
  
  • Moving ANT from gorillas
• Facial prognathism (snout)
• Size of gorillas cranial skull
  
  • Also have chewing muscles on top of skull → forms sagittal crest

Question 4

Progression: Thoax

Vertebral column

Answer 4

• Thorax
  
  • A. Afarensis → Funnel-shaped (like apes) but pelvis shaped like humans
• Vertebral column
  
  • A. Afarensis → thoracic kyphosis
  • A. Africanus → 6 lumbar (like monkeys)
  • Long spinous processes in cervical regions
  • Long transverse processes in lumbar region

Question 5

Progression: Wrist

Hands

Answer 5

• Wrist & Distal radius projection
• Hands
  
  • Flexor ridges → allows strong gripping (Ardipitheus)​

Question 6

Progression: Pelvis shape

Effect on child birth?

Answer 6

• Pelvis shape
  
  • Iliac blades more ANT-LAT
  • A. Afarensis → becoming more similar to humans
  • A. Africanus → Short iliac blades & coronal orientation, hamstrings still ape-like
• Obstetric behaviour (Birth through pelvis)
  
  • A. Afarensis → narrow pelvis → hard to give birth

Question 7

Significance of footprints fossils

Answer 7

• A. Afarensis → showed human bipedal locomotion & foot arches

Question 8

H. ergaster fossils

Answer 8

• Barrel-shapepd ribcage
• Small bowl pelvis, long legs
• ↓prognathism
• Similar vertebral morphology but has 6 lumbar
• Humerofemoral index similar to humans (Afarensis & habilis more like apes)
• Narrow hips, modern pelvic shape

Question 9

H. neanderthalensis

Answer 9

• Broad thorax → large lungs → adaptation for cold air
• Long clavicle
• Robust ribs muscle markings
• Flat & Robust digits → power rather than precision
• Vert column same but more robust
• Spinous process not bifid → hunch back
• Wide, long pubis → ANT placement of sacrum