evidence for a common ancestor for living hominids

Question 1

living hominids

Answer 1

• African apes

- humans

Question 2

To find common ancestor

Answer 2

• fossil record
• genetics (chromosomal DNA and mitochondrial DNA)
• common ancestor has traits of both African apes and humans

Question 3

African apes and humans compared

Answer 3

• common ancestor (6 million years ago)

- split to chimpanzee and humans

Question 4

anatomical similarities

Answer 4

• upright posture
• lack of external tails
• freely rotating arms
• opposable thumbs
• flat nails
• forward facing eyes
• molar and premolar teeth (low and rounded cusps)
• eyes with cones for colour vision
• sexually dimorphic (male and female vary in physical traits)
• large brain to body mass

Question 5

anatomical differences (skeletal)

Answer 5

• (a) arms longer than legs
• (a) long curved fingers and toes
• (a) divergent big toes
• (a) large, elongated ilia (hip bones) parallel to spinal column
• (a) bow-shaped (less curved) spine
• (h) arms shorter than legs
• (h) short straight fingers and toes
• (h) thumbs can grasp objects precisely
• (h) shorter, broader, bowl-shaped pelvis
• (h) longer femurs
• (h) feet : large strong heel , tiny toes with large big toe , longer feet with stable arch
• (h) spine has two major curves : thoracic (away from chest) , lumbar (towards stomach)

Question 6

anatomical differences (brain and skull)

Answer 6

• (h) greater dexterity use of hands
• (h) control of fire
• (h) highly developed language
• (h) foramen magnum (centre under skull)
• (h) large braincase , small jaws , vertical face and chin
• (h) small canine
• (a) pronounced brow ridges
• (a) foramen magnum (rear of skull)
• (a) small braincase , large jaws , sloping face no chin
• (a) large pointed canine projecting beyond other teeth