Human Derived Traits Locomotion differences Dental differences Brain

Human Derived Traits • • • Locomotion differences Dental differences Brain differences Life history differences Cultural adaptations

The Hominoidea

Gibbons

Orangutans

Gorillas

Chimpanzees: common and bonobo

Hominoidea Characteristics • • • No tail Larger body size Rely more on vision Suspensory hanging adaptation Y-5 pattern of molars Arms longer than legs (except humans) • Increased brain size and intelligence • Prolonged growth and development

Differences in the Jaws and Teeth Apes have large anterior teeth which results in a larger face than humans

Apes: Large canines Canine diastema (space for opposing canine) Sectorial premolar (sharpens upper canine) Thin molar enamel

Humans: Small canines Smaller anterior teeth (and a smaller face) Relatively large posterior teeth

Dental arcade shape differences Apes: U-shaped Humans: Parabolic, indicates – • Reduction in size of canine • Loss of diastema & sectorial premolar

Brain Differences Structural similarities exist between human and ape brains Same landmarks are found on both What’s different?

Human Brain – Enlargements and Elaboration of the Cerebral Cortex Frontal lobes – association areas that create more complex models of reality • Areas associated with language on dominant hemisphere • Broca’s area: motor speech • Wernicke’s area: language comprehension

Locomotion Differences: Humans are obligate, habitual bipeds • Requires erect posture • Slow, but energy efficient • Birth and lower back problems • Precarious “…the body, step by step, teeters on the edge of catastrophe” (Napier 1967: 56)

Position of Foramen Magnum • Centered to balance skull on vertebral column in an upright position

Vertebral Column Quadruped – only has a primary curve • Vertebral column is not weight-bearing, vertebrae of equal size • Secondary vertebral curves in humans – neck and lumbar • Vertebrae increase in size from top to bottom

Morphological Differences in the Pelvis APE • Tall and narrow • Flat, or compressed anterior to posterior (front to back) HUMAN • Short and broad • Curved