Bipedalism

Bipedal Locomotion

• moving on two legs

• suspensory upper body

  • rotating shoulders

  • flexible wrists (can brachiate)

  • round rib cage

  • extending elbow

  • short lower back

• derived pelvis

  • bowl-shaped pelvic complex (wide across, short up and down)

Bipedal osteology

• spine right beneath our skulls

  • foramen magnum underneath the skull - is an indicator for upright posture or bipedalism

• spine withS curve (two distinct curves)

• lumbar spine with short (superio-inferiorly) and broad (transversely) vertebral bodies for increased flexibility

• sacrum in broad transversely (right to left) - has changed to accommodate all weight being put on two legs

• Illium is curved and wide anterior-posteriorly (front to back)

• Os Coxa is short superior-inferiorly (up and down)

• shape of the bipedal pelvis has an impact on how babies are born (what whay the baby is facing)

• narrow Birth Canal (pelvic inlet) antirior-posterior (front to back)

• valgus knees (allow us to walk more smoothly)

• long femoral neck (due to changing orientation of femur)

Habitual Bipedalism

• bipedal locomotion most often used by hominins

• retain ancestral anatomical locomotor structures

Obligate Bipedalism

• major structural changes in the body occured to promote energy efficient bipedalism

• other forms of locomotion are impossible, or possible but not effective

bipedalism adaption

• climate change between 8 and 6mya

  • cooling in the northern hemisphere

  • expanding savannah in equatorial africa

  • reduction of arboreal environment