Hominin Evolution

1. Hominin Evolution

2. Definitions • Hominin – term that refers to humans and their extinct erect-walking ancestors. They belong to the tribe homini. • Sometimes the word ‘hominid’ is used instead of hominin but this term refers to outdated classification so hominin is the preferred term. • Hominoid – term that refers to any member of the superfamily ‘hominoidae’ • Humans are both hominins and hominoids

3. Classification of Humans Kingdom Animal Chordata (vertebrates) Phylum Class Mammalia Aves Eutheria (placental) Marsupialia Monotremes Sub-Class Primates Chiroptera Order

4. Primates • Primate – name of a taxonomic group to which humans, monkeys and apes belong. They have certain features in common: • Five digits on hands and feet that can curl/bend around objects • Thumbs are ‘opposable’ meaning that they can be brought into contact with other digits • Flat nails on their digits with tips of their digits used for sensing touch

5. Primate features 5 Digits Opposable Thumb Flat nails

6. Classification of Humans Order Primates Sub-order Anthropoidea Prosimii Super-family Hominoidae Cercopithecoida Ceboidea Family Hominidae Hylobatidae Sub-family Homininae Gorillinae Ponginae Tribe Hominini Panini Genus Homo Pan

7. Evolution of Primates Classification reflects the predicted evolutionary history 5 MYR 7 MYR 15 MYR 17 MYR 40 MYR 30 MYR

8. Hominidae skulls From left to right: The skulls of a Gorrilla, Chimp, Orang-utan, and a common ancestor to humans and chimps

9. Hominins • Humans are the only living members of the tribe ‘homini’ • Hominins are distinguished from other members of the family hominidae because they are able to walk upright (bi-pedalism)

10. The foramen magnum 1. Chimpanzee 2. Australopithecus africanus 3. Homo erectus 4. Homo sapiens

11. The foramen magnum

12. Hominin Pelvis Structure

13. Hominin Evolution Hominins

14. Hominin Evolution • Oldest fossils found in Africa – hominins originated in Africa • Earliest evidence of hominins are 6 million years old • No evidence for genus Homo before 2.4 million years ago

15. Hominin Evolution • Several different hominin species existed over certain time-frames for reasonably lengthy periods suggesting: • Different niches occupied • Probably did not compete for food • Possibly were able to interbreed for some of the time • Eventually some of the co-existing species may have begun to compete for food and/or habitat, leading to the extinction of some species

17. The genus Australopithecus • Small- brained • Large-toothed and large protruding jaws • Walked upright – bi-pedal • Two types: • Graciles (slender) • Robusts (heavy build) – now separate genus Paranthropus • The graciles are possibly ancestral to the human line • Tool use limited – evidence has been found which suggests they may have used rocks to kill other animals and break bones to extract marrow

18. The genus Australopithecus • Sexual dimorphism- differences in body structure and specifically body mass of adult males and females • Zygomatic arches (cheekbones) – more pronounced – probably large cheek muscles for chewing suggests high fibrous content in diet • Larger waistline – longer digestive tract due to herbivorous diet • Habitats can be inferred from fossil evidence – varied amongst species – again suggesting different niches

19. The genus Homo • Evidence found of more complex tools being made and used • Diet changed – • smaller teeth • fossil evidence of animal remains near human fossils • larger brain size • change in rib-cage size and shape Suggests that meat became part of the diet

20. Australopithecus Vs. Homo

21. The genus Homo • Compared to Australopithecus species Homo species have: • Larger brains (larger cranium size): • A. aferensis had a brain size of ~400-500mL • H. habilis had a brain size of ~600-700mL • H. sapiens has a brain size of ~1300-1400mL • Smaller teeth • Larger skull – increased height and width, straight forehead instead of sloping like the ancestral skulls • Smaller brow-ridge http://www.amnh.org/exhibitions/permanent/humanorigins/meettherelatives/w5i1.html

22. Homo Erectus • H. erectus probably evolved from H.habilis or H.ergaster around 2 million years ago • First hominin fossils to be found on continents other than Africa - emigrants

23. Homo heidelbergensis • Considered to be an intermediary or transitional form between Homo erectus and Homo sapiens • Fossils are dated between 400,000 to as recent as 40,000 years ago • Located in Africa, Asia and Europe

24. Homo neanderthalensis • Strongly built • Evidence has been found to suggest that they: • Made sophisticated tools • Built shelters • Sometimes buried their dead • Made clothing from animal skins • Fossils date between 150,000 to 35,000 years ago

25. Homo neanderthalensis • Existence overlaps with the earliest Homo sapiens • Therefore not likely to be an ancestor but a cousin of the modern human • Neanderthals are thought to have become extinct through competition with H. sapiens or disease

26. Homo Sapiens • Earliest H. sapiens existed in Africa around 130,000 years ago • Thought to have migrated North to Asia and Europe • Probably the first human species to use complex speech

27. Cro-Magnon Man • Considered to be a ‘modern’ H. sapiens • Produced art in caves depicting hunting • Found in regions of France and Spain • Produced very sophisticated tools such as needles, fish hooks, chisels etc. • Tools and figurines made of bone have been found • Buried their dead with objects such as figurines and necklaces

28. Cro-Magnon Cave Art

30. HOMO HABILIS ~ LIVED: 2.4 to 1.6 million years ago HABITAT: Tropical Africa DIET: Omnivorous – nuts, seeds, tubers, fruits, some meatBEHAVIOUR: inquisitive, tool makers, cooperative • HOMO SAPIEN ~ LIVED: 200,000 years ago to present HABITAT: All DIET: Omnivorous - meat, vegetables, tubers, nuts, complex foods BEHAVIOUR: complex • HOMO FLORESIENSIS ~ LIVED: 95,000 to 13,000 years ago HABITAT: Flores, Indonesia (tropical). Not a direct ancestor • HOMO ERECTUS ~ LIVED: 1.8 million years to 100,000 years ago HABITAT: Tropical to temperate - Africa, Asia, Europe DIET: Omnivorous - meat, tubers, fruits, nuts BEHAVIOUR: migrated, social relationships, used fire • PARANTHROPUS BOISEI ~ LIVED: 2.3 to 1.4 million years ago HABITAT: Tropical Africa DIET: Omnivorous - nuts, seeds, leaves, tubers, fruits, maybe some meat Not a direct ancestor • HOMO HEIDELBERGENSIS ~ LIVED: 700,000 to 300,000 years ago HABITAT: Temperate and tropical, Africa and Europe DIET: Omnivorous - meat, vegetables, tubers, nuts BEHAVIOUR: creative/imaginitive • HOMO NEANDERTHALENSIS ~ LIVED: 250,000 to 30,000 years ago HABITAT: Europe and Western Asia DIET: Relied heavily on meat, such as bison, deer and musk ox BEHAVIOUR: tough, stoic, used animal skins for warmth

31. Comparing H. erectus, H. heidelbergensis & H. sapiens

32. Differing Hypotheses for the Human Evolution Story • Out-of-Africa: Modern humans originated in Africa and then migrated to other continents where they competed with and out-lived more primitive populations • Regional continuity hypothesis: Modern humans evolved in different regions from existing H. erectus populations in each region

33. Early Human Migrations based on mtDNA haplogroups

34. Differences in modern human populations • Differences in modern human populations result from: • Biological evolution through natural selection resulting in physical, biochemical and behavioural differences between populations (driven by adaptations which are genetically determined) • Cultural evolution – changes in human society – passed on to people that are not genetically related • Technological evolution – expressed through production and use of tools

35. Questions to complete • All Quickcheck • Biochallenge Page 617 (need internet access) • Chapter Review: 2, 3, 4, 5, 7, 8, 9