Hominid Evolution

• What is the effect of the increase in size of the cerebrum on the brain?

  It takes up a larger portion of the brain.
• How do increased convolutions on the surface of the cerebrum affect the brain?

  They increase the surface area of the brain.
• What abilities were enabled by the increase in cerebral cortex size?

  • Development of toolmaking skills in chimpanzees and humans
  • Complex social behavior to respond to environmental problems
  • Greater room for thinking
• What is the function of digits in primates?

  Digits allow them to wrap around branches.
• What is the significance of opposable thumbs and big toes in primates?

  They allow the digits to touch each other, enhancing grasping ability.
• What change occurred in humans regarding the opposable big toe?

  Humans lost their opposable big toe to enable feet to become a weight-bearing base in bipedalism.
• How do nails in primates compare to claws?

  Nails make grasping easier than claws.
• What feature of the human thumb allows for greater manipulation of objects?


  The human thumb is long.
• What advantage does the human thumb provide for writing?

  It allows for a better precision grip.
• What are the increased features associated with digits in primates?

  • Mobility
  • Ability to move digits
  • Length of opposite digit
• What does dentition refer to in primates?

  It refers to the arrangement and structure of teeth.
• What is the dental formula?


  It is the number of each type of tooth in one quarter of the jaw.
• What is prognathism?


  It is the extension or bulging out of the lower jaw.
• What causes prognathism?


  It occurs when teeth are not properly aligned due to the shape of the face bones.
• How does prognathism change in higher order primates?

  There is a reduction in prognathism.
• What is the significance of reduced prognathism in higher order primates?

  It enables the skull to balance on top of the vertebral canal.
• What anatomical changes accompany the reduction in prognathism?

  It causes a reduction in neck muscles to support the skull.
• How does reduced prognathism affect teeth size and number?

  It causes a reduction in teeth size and number.
• What dietary changes are associated with reduced prognathism?


  It leads to a change in diet.
• How does reduced prognathism relate to the development of speech?

  It facilitates the development of speech.
• What is the zygomatic arch?


  It is the bony arch behind the cheeks.
• How does the size of the zygomatic arch change in higher order primates?

  There is a reduction in size and prominence.
• What is the function of the brow ridge in higher order primates?

  There is a reduction of the prominence of the brow ridge.
• What is the sagittal crest?


  It provides attachment for strong jaw muscles for chewing.
• In which type of hominids is the sagittal crest present?

  It is present in bipedal hominids.
• How did tools evolve in complexity?

  • Tools became more complex in size, manufacture, and use.
  • Greater workmanship and finer work were achieved.
  • More time was available to create tools.
• How did efficient tools impact brain size?

  They supported a larger brain due to protein intake from better hunting abilities.
• What is the relationship between larger brain size and social behavior?

  A larger brain facilitates cooperation and communication.
• What changes occur in the frontal lobe with increased cranial capacity?

  There is an increase in frontal lobe size.
• How does bipedalism affect behavioral changes in hominids?

  Bipedalism leads to behavioral changes in hominids.
• What evolutionary development is associated with increased cranial capacity?

  Speech and language evolved due to increased cranial capacity.
• What are the cranial features of great apes compared to hominids?

  Great Ape:

  • Decreased cranial capacity (average size of 500cc)
  • Less convoluted cerebral cortex
  • Smaller frontal lobe
  • Prominent brow ridge
  • Prognathic/sloping face
  • 'U' shaped foramen magnum
  • Large teeth and molars

  
  

  Hominid:

  • Increased cranial capacity (average size of 1400cc)
  • More convoluted cerebral cortex
  • Much larger frontal lobe
  • Reduced/absent brow ridge
  • Flatter/vertical face
  • Central/underneath foramen magnum
  • Smaller teeth and molars
• What are the anatomical characteristics of quadrupedal primates compared to bipedal primates?

  Quadrupedal Primates:

  • C-shaped vertebral column
  • Long and narrow pelvis at an angle
  • Vertical femur
  • Longitudinal arch in the foot
  • Foramen magnum positioned towards the back of the skull

  
  

  Bipedal Primates:

  • S-shaped vertebral column
  • Short and broad pelvis aligned with the vertebral column
  • Femur converges inwards from hip to knee
  • Transverse and longitudinal arches in the foot
  • Foramen magnum positioned more anteriorly for neck muscle attachment
• What are the feature advantages for modern humans?

  • Opposable Thumb: Allows for precision grip and fine manipulation of objects.
  • Reduced Prognathism: Greater reliance on sight and better balance of skull in bipedalism.
  • Cerebral Cortex: Increase means site of higher functions (vision, tool making, etc.).
  • Feet: Support entire weight of the body for bipedal locomotion.
  • Jaw and Teeth: Smaller jaw aids in balance of skull for bipedalism.
  • Pelvis: Greater stability for bipedal locomotion.
• What are the advantages of bipedalism?

  • Energy-efficient means of covering long distances.
  • Leaves hands free to carry tools, food, weapons, and young.
  • Hominins stand taller for better vision to spot food and predators.
  • Larger appearance deters predators.
• What are the characteristics of Oldowan tools?

  • Made from stones, pebbles, or rocks.
  • Created by flaking rocks together.
  • Used for butchering and grinding tough plant materials.
• What are the characteristics of Acheulian tools?

  • Made using the Levallois method with a large flake removed from a stone core.
  • Flakes are reworked on edges.
  • Used for butchering and cutting wood.
• What are the characteristics of Mousterian tools?

  • Made using the Levallois method with a large flake removed from a stone core.
  • Flakes are reworked on edges.
  • Used for spearing to hunt animals and scraping to make clothing.
• What trends are observed in the manufacturing of tools?

  • Greater variety of materials used indicates more variety in resources.
  • Increased workmanship shows that hominids had time to create and did finer work.