2 Anatomical similarities between African apes and humans Anatomical differences between African apes and humans
NOTES
- enrichment - enrichment
Humans share the following characteristics with other primates:
African apes Humans
• opposable thumbs that allow monkeys to have a power grip, while humans
are capable of a power grip as well as a precision grip (fine motor ability) Quadrupedal - knuckle-walkers Bipedal - walk upright on two legs
Foramen magnum (opening for Foramen magnum closer to front of
spinal cord) at back of skull skull (central under skull)
C-shaped vertebral column S-shaped vertebral column
Arms longer and stronger than legs Arms shorter and weaker than legs
Knee joints smaller and weaker Knee joints larger and stronger
Opposable (grasping) big toe with Non-opposable (forward-thrusting)
power grip big toe in line with other toes
Humans: power grip and precision grip Flat feet Curved foot arch
(fine motor grip) Long and narrow pelvis Short and wide pelvis
Apes: power grip
Smaller, less developed brain Large, developed brain
• two hands, each with five fingers; and two feet each with five toes Large, prominent canines Smaller canines; the same size as
other teeth
• long arms that rotate freely as shoulder joints allow movement in all directions
Thin tooth enamel Thick tooth enamel
• naked fingertips and toes ending in flat nails
Large, prominent jawbone with no Rounded jaw with developed chin
• a reduced snout with weakened sense of smell (reduced olfactory brain chin (prognathism) (reduced prognathism)
centres) Wider, sloping face Narrow, flat face
• stereoscopic vision as the eyes face forward providing depth of field - 3D vision Narrow, rectangular palate Wider, more curved palate
• eyes have cones (as well as rods) making colour vision possible Prominent cranial and brow ridges Reduced cranial and brow ridges
UNIT 2: HUMAN EVOLUTION
• brain centres that process information from hands and eyes are enlarged
• no tail EVIDENCE OF COMMON ANCESTORS FOR LIVING
• sexual dimorphism where males and females are clearly distinguished HOMINIDS (including humans)
• have molars and premolars with rounded cusps • The evolutionary theory does not state that humans evolved from the
chimpanzee or the gorilla, but it proposes that they share a common ancestor.
• Scientists are searching for a common ancestor of all living hominids.
• The big question scientists have to answer is whether the common ancestor
was ape-like or human-like.
• Remains of earlier hominids are very rare.
Copyright © The Answer Series: Photocopying of this material is illegal 2.25
, • There are three main lines of evidence that indicate hominids may have
shared a common ancestor:
• Hominid fossils show evidence of a transition from quadrupedalism to
bipedalism.
2
NOTES
Fossil evidence
Genetic evidence Various explanations are given for the transition from quadrupedalism to
bipedalism. Many anthropologists question whether these advantages
Archaeological evidence were sufficient to cause the significant changes involved in the evolution
of bipedalism.
Fossil evidence Advantages of bipedalism include:
Upright bodies expose a smaller surface area to the sun which reduces
• Paleontologists study fossils to provide more information on the structure, risk of overheating while hunting, foraging or escaping predators.
movement, lifestyle and environment of a particular species.
Upright bodies expose a larger surface area to air currents which
• Certain features of hominid fossils indicate how changes occurred over time. causes cooling and reduces dependency on water.
• Hominid fossils are rarely complete and consist mainly of fragments. Hands are free to use tools, prepare food, carry young, hunt or fight.
• Most hominid fossils are teeth, jaw bones or skull fragments. Vision extends further over the tall grass of the savannah to find food
or avoid predators.
• The remains of feet, hands, pelvic bones or vertebral columns are scarce.
Adaptability to occupy a wider range of habitats.
• Long bones e.g. femurs are more commonly found.
• In the search for a common ancestor for hominids, palaeontologists look
particularly at the following features of hominid fossils: • For early hominids to become bipedal and walk upright, their skeletons had to
change quite considerably.
bipedalism brain size
dentition (teeth) prognathism • The following changes in structure are observed in humans:
palate shape cranial and brow ridges In bipedal humans the foramen magnum shifted forward so that the skull
rests on top of the vertebral column and the eyes face forward. The foramen
Bipedalism magnum is positioned centrally at the bottom of the skull. In quadrupedal
• The greatest observable difference between apes and humans lies in the apes the head is positioned in front of the vertebral column with the foramen
difference in posture and method of locomotion. magnum at the back of the skull.
• Apes are four-footed (quadrupedal) with gorillas and chimpanzees
demonstrating a particular manner of walking, i.e. knuckle-walking.
UNIT 2: HUMAN EVOLUTION
• Humans, however, are bipedal and
walk upright.
A B C
A. Chimpanzees: foramen magnum is at the back of the skull
B. Early Homo species: foramen magnum is closer to the front for stable
upright walking
C. Homo sapiens: foramen magnum is directly above the spine to balance
Chimpanzee (quadrupedal)
the head above the vertebrae
Human (bipedal)
2.26 Copyright © The Answer Series: Photocopying of this material is illegal
NOTES
- enrichment - enrichment
Humans share the following characteristics with other primates:
African apes Humans
• opposable thumbs that allow monkeys to have a power grip, while humans
are capable of a power grip as well as a precision grip (fine motor ability) Quadrupedal - knuckle-walkers Bipedal - walk upright on two legs
Foramen magnum (opening for Foramen magnum closer to front of
spinal cord) at back of skull skull (central under skull)
C-shaped vertebral column S-shaped vertebral column
Arms longer and stronger than legs Arms shorter and weaker than legs
Knee joints smaller and weaker Knee joints larger and stronger
Opposable (grasping) big toe with Non-opposable (forward-thrusting)
power grip big toe in line with other toes
Humans: power grip and precision grip Flat feet Curved foot arch
(fine motor grip) Long and narrow pelvis Short and wide pelvis
Apes: power grip
Smaller, less developed brain Large, developed brain
• two hands, each with five fingers; and two feet each with five toes Large, prominent canines Smaller canines; the same size as
other teeth
• long arms that rotate freely as shoulder joints allow movement in all directions
Thin tooth enamel Thick tooth enamel
• naked fingertips and toes ending in flat nails
Large, prominent jawbone with no Rounded jaw with developed chin
• a reduced snout with weakened sense of smell (reduced olfactory brain chin (prognathism) (reduced prognathism)
centres) Wider, sloping face Narrow, flat face
• stereoscopic vision as the eyes face forward providing depth of field - 3D vision Narrow, rectangular palate Wider, more curved palate
• eyes have cones (as well as rods) making colour vision possible Prominent cranial and brow ridges Reduced cranial and brow ridges
UNIT 2: HUMAN EVOLUTION
• brain centres that process information from hands and eyes are enlarged
• no tail EVIDENCE OF COMMON ANCESTORS FOR LIVING
• sexual dimorphism where males and females are clearly distinguished HOMINIDS (including humans)
• have molars and premolars with rounded cusps • The evolutionary theory does not state that humans evolved from the
chimpanzee or the gorilla, but it proposes that they share a common ancestor.
• Scientists are searching for a common ancestor of all living hominids.
• The big question scientists have to answer is whether the common ancestor
was ape-like or human-like.
• Remains of earlier hominids are very rare.
Copyright © The Answer Series: Photocopying of this material is illegal 2.25
, • There are three main lines of evidence that indicate hominids may have
shared a common ancestor:
• Hominid fossils show evidence of a transition from quadrupedalism to
bipedalism.
2
NOTES
Fossil evidence
Genetic evidence Various explanations are given for the transition from quadrupedalism to
bipedalism. Many anthropologists question whether these advantages
Archaeological evidence were sufficient to cause the significant changes involved in the evolution
of bipedalism.
Fossil evidence Advantages of bipedalism include:
Upright bodies expose a smaller surface area to the sun which reduces
• Paleontologists study fossils to provide more information on the structure, risk of overheating while hunting, foraging or escaping predators.
movement, lifestyle and environment of a particular species.
Upright bodies expose a larger surface area to air currents which
• Certain features of hominid fossils indicate how changes occurred over time. causes cooling and reduces dependency on water.
• Hominid fossils are rarely complete and consist mainly of fragments. Hands are free to use tools, prepare food, carry young, hunt or fight.
• Most hominid fossils are teeth, jaw bones or skull fragments. Vision extends further over the tall grass of the savannah to find food
or avoid predators.
• The remains of feet, hands, pelvic bones or vertebral columns are scarce.
Adaptability to occupy a wider range of habitats.
• Long bones e.g. femurs are more commonly found.
• In the search for a common ancestor for hominids, palaeontologists look
particularly at the following features of hominid fossils: • For early hominids to become bipedal and walk upright, their skeletons had to
change quite considerably.
bipedalism brain size
dentition (teeth) prognathism • The following changes in structure are observed in humans:
palate shape cranial and brow ridges In bipedal humans the foramen magnum shifted forward so that the skull
rests on top of the vertebral column and the eyes face forward. The foramen
Bipedalism magnum is positioned centrally at the bottom of the skull. In quadrupedal
• The greatest observable difference between apes and humans lies in the apes the head is positioned in front of the vertebral column with the foramen
difference in posture and method of locomotion. magnum at the back of the skull.
• Apes are four-footed (quadrupedal) with gorillas and chimpanzees
demonstrating a particular manner of walking, i.e. knuckle-walking.
UNIT 2: HUMAN EVOLUTION
• Humans, however, are bipedal and
walk upright.
A B C
A. Chimpanzees: foramen magnum is at the back of the skull
B. Early Homo species: foramen magnum is closer to the front for stable
upright walking
C. Homo sapiens: foramen magnum is directly above the spine to balance
Chimpanzee (quadrupedal)
the head above the vertebrae
Human (bipedal)
2.26 Copyright © The Answer Series: Photocopying of this material is illegal
