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Hominin Evolution

Hominin Evolution. Chapter 15. Taung Child. Skull with petrified remains of child found in South Africa.Brain was distinct from brain of ape. Possesed ape like features and human feature-juvenile intermediate between apes & humans- Australopithecus africanus .

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Hominin Evolution

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  1. Hominin Evolution Chapter 15

  2. Taung Child • Skull with petrified remains of child found in South Africa.Brain was distinct from brain of ape. • Possesed ape like features and human feature-juvenile intermediate between apes & humans- Australopithecus africanus. • Evidence from foramen magnum on undersurface of cranium-showed that it walked upright. Place were spinal cord leaves brain & enters vertebral column. Front means walks upright!

  3. Autralopithecus Africanus • Found in 1925. • Tuang skull was the first hominin fossil to be discovered. Was not human but member of a species which could walk upright (genus Homo). Primates who can walk upright called hominins. • Other species found-all Australopithecus were ancestors of humans.

  4. Lucy-Female Skeleton!! • Not a human or hominin. Part of species Australopithecus afarensis • Said to be a common ancestor of humans. 40% of skeleton found, 1m tall & lived 3000000 yrs ago. • Female aged between 25-30 yrs old. • Lucy could walk upright because of bone structure.

  5. How did Lucy walk? • Femur (thigh) is at an angle to the tibia (shin). Also locking knee joint. In Lucy, femur is angled out of line of tibia-evidence she walked erect. • Thought that Lucy also swung in trees-brachiation. Concluded: • Skeletal changes that allowed for upright walking appeared before genus Homo-3.5 million yrs ago. • Present in hominin’s with reduced brain size. • Erect walking seen before 1st stone tools were found. • Upright walking was not advantageous selection pressure.

  6. Classification of human species • Humans are apart of phylum Chordata, class Mammalia (mammals). • Mammals have: • 3 bones in middle ear • Diaphragm-separate chest from abdomen • Body hair/fur • Mammary glands • Lower jaw made of single bone • Teeth: incisors, canines, pre-molars, molars. • Humans part of Order Primates • Prosimians-lemurs • New world- (SA) spider monkeys • Old world (Africa, Asia)-baboons • Apes- Chimps, gorillas, humans

  7. Humans are hominoids • Members of superfamily Hominoidea-all apes included. • Separated even further. Chimps & humans separated into Homininae. • We are hominin’s as we walk upright. Have bipedal(2 footed) movement. Walk on 4 limbs (quadrupedal). • We are the only living hominin (Homo sapiens). Evidence as explained before (leg bones). Other evidence are fossilised footprints in Tanzania. 3.5 million yrs old.

  8. Evolution of Primates • All apes evolved within 65 million yrs. • Chimps diverged from Humans 5 million yrs ago. • We didn’t evolve from chimps, human line and African ape shared a common ancestor, which diverged into 2 lines. • Changes: • Brains of non-hominins enlarged • Face shortened & flattened • Jaws & teeth became smaller • Ability to make tools • Can grasp and use thumb • Final product-humans

  9. Our ancestors • Genus Australopithecus- small brained, large-toothed primates. Walk erect. All in Africa. • Graciles (slender) and Robusts (heavily built). • Graciles ancestor of Homo species. Lucy’s jaw shape similar to that of human (intermediate shape, no large canine) but still has diastema (chimp) • Robust Autralopithecus had heavily built skull, heavy brow ridge, big molar teeth & bony crest. Very diff. to humans. VIDEO

  10. Our ancestors Sexual dimorphism • Differences in males and females in average height, body mass or other features. • Females distinctly smaller in all areas. Gracile Robust

  11. How early Hominin’s lived Social orginisation Similar to chimps as in group of related males defend groups of females. Diets Size of teeth, tooth ware, jaw size and jaw muscle. Robust ate tough & fibrous vegetable matter. Seen in ware of teeth. Gracile also ate similar food, but less fibrous. Why? Jaw muscles very large in robust so allowed them to eat this.

  12. How early Hominin’s lived Waistline Herbivores so had large digestive tracts-larger waist and ribcage wider to fit large guts. Homo-erectus (early human) had smaller waistline as smaller tract because change in diet-meat! Habitat Early hominin’s found in forest/woodland areas. Later hominin’s found in grassland savannah habitats.

  13. How early Hominin’s lived Locomotion Australopithecus capable of bipedalism but not long strides. Had long curved fingers/toes & longer arms. So used bipedal locomotion in open areas but adapted to forest- arboreal. Upright walking advantage in open area as increased vision. Also better cooling system.

  14. Genus Homo evolved • Africa is where genus Homo 1st appeared 2.4 million yrs ago. Diff. from Australopithcus: • Reduction in size of teeth • Increase in brain size, cranium, height & vertical slope of forehead & width of skull. • Brain capacity imp. feature in genus Homo. Inc. in brain size resulted from natural selection favouring greater intelligence • As brain size inc. body mass also increases. VIDEO- intelligence

  15. Homo habilis (Habilines) -1st tool maker Homo Habilis- 2.4 myo and was the 1st human. Why? Had greater brain size & smaller teeth than Australopithecus. Simple stone tools found in sites where fossils have been found. 1st Hominin to use sharp edged flakes as tools-Oldowan tools Scrapers: scrape flesh off Cutters: cut tough outer hides Choppers: cut tendons/bones 1st hominin to add meat in diet.

  16. Homo habilis (Habilines) Thought to hunt in groups Use tools to kill, cut meat & carry to safe area. Variation in fossil, so split into 2 genus: Homo habilis- smaller brain & prominent brow ridge Homo rudolfensis- larger brain & smaller brow ridge 2 million yrs ago, 2 diff. human species existed. Both only in Africa.

  17. Homo Erectus- 1st human immigrants H.erectus seen 1.8 mya. and seen until 300000 yrs ago. Oldest fossil seen in Kenya but fossils found all over world-migrated! Key differences between Homo Sapiens. More prominent brow ridge, face protrudes more, smaller cranial capacity Brain 900 mililitres so more smarter. New behaviours: Controlled use of fire-evid. In ash deposists. Used for warmth, cooking, protection, light. Crafting elaborate tools: axes and stone/bone tools. Systematic hunting: Early communication in sounds. Evid. In vertebra, hole in neck which allowed simple sounds. Meet Ha, Meagan, Ivan, Allen and Jack…

  18. Homo neanderthalensis 1856-Neanderthals found. Found 1500000-35000 thousand yrs ago. Overlapped with humans so not our ancestor. Large brain, strongly built, long, wide skulls, brow ridge, rounded chins, large eye sockets. Made tools, lived in caves, made clothing & used fire VIDEO: Face and run Joel and David 

  19. Which is Human and H. erectus?

  20. Homo Sapiens • Existed 130,000 yrs ago. • Also called CroMagnons- similar to us, skilled tool makers • Have uniform teeth • Buried their dead-decorated with necklaces. Up to 30,000 yrs ago. • Modern humans capable of abstract thought, complex speech, use symbols and have ceremonies. • We started evolving 5 mya- diverged from ape line. Evo pattern is branched. • 2.4 mya-first ‘human’ appeared (H. habilis)-large brain, small teeth & tools. • H. erectus then evolved as inc. in brain capacity-fire, tools etc… • Only 1 alive: H. sapiens 3 examples of the de-evolution of man….

  21. General differences & Info • H. erectus & Australopithecus afarensis • H. erectus has larger brain case • H. erectus has less prominent brow ridge • More parabolic jaw • H. sapeins & H. neaderthalensis: why no interbreeding? • Diff. customs and lifestyle • Different mating behaviours • Mating occurred but no viable offspring • CAN WE NOT EVOLVE FURTHER? • Yes: Medical advances means that modern humans are interfering in their own selection to the extent that natural selection no longer exists • NO: Humans still exist in many different env. & are still subjected to different pressures.

  22. Out of Africa or not? VIDEO • 2 theories: out of Africa hypothesis or Regional continuity hypothesis.

  23. Changes in human populations Biological evolution Changes in human pop that resulted from natural selection acting over generations on inherited phenotypes in set environmental conditions. Physical traits: skin colour, hair Biochemical: ABO/Rhesus blood type Physiological: tolerance to milk As env. change, selective advantage changes.

  24. Changes in human populations Human Cultural Evolution Refers to any form of learned behaviour-making tools, learning rules, music. Rock Paintings a sign of cultural evolution- 20000 yrs ago. When persistent/common changes occur in pop because of learned/ imitated behaviours- cultural evolution. Changes are socially transmitted, not inherited. Clothing style, mobile phones, music, art etc…

  25. Changes in human populations Technological Evolution Changes over time in technology that give humans increased control over their env. (change from stone tools to metal tools, steam to electric power. 1930’s TV, 1895’s Radio In hominids- use of tools and fire.

  26. Cultural evolution affecting technological evolution. Allowed development of speech, writing and painting to give instructions to build. Physical features: The brain= inc. size inc. capacity to process info. Precision grip= make tools for fire manipulation Structures involved with speech let to communication through speech. • How are ancestors footprints similar? • Big toe parallel to other toes • Big toe not opposable • Prints indicate 2 footprints

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