Summary
Summary Human evolution
- Course
- Life Sciences
- Institution
- 12th Grade
Summary and notes needed for grade 12, Relative to both IEB and NSC
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- Hominid →group consisting of modern humans, chimpanzees, gorillas,orangutans & all their ancestors (all members of Hominidae)
- Charles Darwin suggested humans & apes shared a common ancestor - Hominin → modern humans, extinct human species & all our
- James Burnet suggested humans were related to orangutans & that all immediate ancestors (eg. members of Homo, Australopithecus,
intermediate types of humans may be found in Africa. Paranthropus & Ardipithecus)
- Carl Linnaeus classified modern humans as homo sapiens in the Order
Primates of Class Mammalia.
- Homo sapiens sapiens = distinguishes us from earlier humans SIMILARITIES IN AFRICAN APES & HUMANS
- Early humans = “ape men” (showed shared some characteristics of
apes AND of humans) - African apes = gorillas, chimps, bonobos (slightly larger than chimps)
- Earlier humans belonged to different species: - Earliest mammals lived on trees → arboreal life
> Homo habilis - Adaptations to arboreal life = structure of upper limbs, brain & eyes
> Homo erectus - Other adaptations shared by all primates = no. of offspring & posture
> Homo neanderthalensis
THE UPPER LIMBS:
- Primates have free movement due to long upper arms because of
KINGDOM ANIMALIA: glenoid cavity (into which head of humerus fits) & the fact that
scapulae aren’t attached to vertebral column.
Invertebrates Vertebrates - Long arms = used for plucking fruit
Fish Frogs Birds Reptiles Mammals - Forearms can be rotated around elbow joint
- Flat nails instead of claws
Order Primates
- Sensitive fingertips = precision work
Sub order Prosimii Sub order Anthropoidea - Thumbs work in opposite direction to fingers (opposable thumbs)
Family Hylobatidae Family Hominidae - Hands can form power grip (climbing) / precision grip (tools)
Gibbons Orangutans, gorillas, chimps & humans THE BRAIN:
- Large brains compared to body masses → make sense of large
amounts of info
- Parts that interpret touch & sight are enlarged
- Parts that interpret smell (olfactory centre) is reduced
, back
VISION
base
- Eyes in front
- Binocular vision (use 2 eyes)
- Stereoscopic vision (observe the solid nature of objects)
- Eyes have cones & rods for colour vision & greater clarity
NO. OF OFFSPRING PRODUCED:
- Fewer offspring than other mammals
- Young are dependant on parents for longer
- Adults teach the young essential survival skills
UPRIGHT POSTURE: FOSSIL EVIDENCE: A FLAT FACE
- Can sit with head held high - Modern humans = flat face → makes us distinct from earlier homos
- Gives better view of surroundings - Foreheads don’t slope backwards like ape men’s do
- Allows animal to walk on 2 legs → frees upper limbs for carrying - Our lower jaws have a well-developed chin
- Bones of our noses & jaws don’t stick out as much (we are not
prognathous)
DIFFERENCES IN AFRICAN APES & HUMANS - Our brow and cranial ridges are not as pronounced as ape men’s
FOSSIL EVIDENCE: BIPEDALISM
- Humans walk on 2 feet (bipedal) permanently – advantages:
> Hands are free for carrying food
> Better view of surroundings
> Movement is more efficient
> Faster cooling of the body
> Display of male sex organs as part of courtship behaviour
- Bipedalism results in straightened spine & broader pelvic girdle
(supports body weight)
- Examining fossils shows whether an organism was bipedal /
quadrupedal by looking at position of foramen magnum → confirms
bipedalism is more recent & shows some had intermediate position.
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