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Human Evolution: A Concise Look at Key Events and Species
- 2. Outlines Introduction Taxonomic position of human in the animal kingdom Extinct and extant hominids important human features The evolutionary relationships among huminids Migration of hominids out of Africa the origin of Homo sapience 2/4/2020By:Asmamaw Menelih2
- 3. Introduction Human evolution is the lengthy process of change by which people originated from apelike ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people originated from apelike ancestors about 5–10 million years ago. These ancestors were tree-dwelling primates. Human evolution began from these ancestors. 2/4/2020By:Asmamaw Menelih3
- 4. Taxonomic position of human in the animal kingdom Humans are categorized under order primates. Primates have, compared with other mammals, relatively flat faces and large brains. Their flat faces provide their two eyes with a large overlap in their visual fields, giving good stereoscopic vision. Stereoscopic vision improves perception of depth, and is advantageous in leaping between branches. Arboreal primates also have their thumbs and big toes relatively separate from their other four digits. This allows them to grip branches. 2/4/2020By:Asmamaw Menelih4
- 5. Features of Primates Origins estimated back to 65 MYA Oldest fossil only goes back 45 MYA Insect eating nocturnal mammal Derived traits for life in trees in the tropics Grasping hands and feet Separate big toe / thumb Sensitive Skin ridges on hands and feet Large brains – eye hand coordination- brachiating Short jaws 2/4/2020By:Asmamaw Menelih5
- 6. Cont… Forward looking eyes – close together, stereo vision Flat nails – not claws Long parental care with learned behaviors. Single births Fully opposable thumb 2/4/2020By:Asmamaw Menelih6
- 7. Primate groups 2/4/2020By:Asmamaw Menelih7 Prosimians include Lemurs, Tarsiers Probably more similar to origin arboreal ancestral primates Anthropoids Include Monkeys, Apes and Humans Split from the Prosimians about 45 MYA
- 9. Anthropoids 2/4/2020By:Asmamaw Menelih9 Include the Monekys and the Hominiods Monkeys evolved in two areas ,split about 35 MYA New World monkeys (older), Origin; North America, Central America, and South America. all arboreal have prehensile tail, nostrils open to the sides Squirrel and capuchin monkeys Old World monkeys Origin Africa, Asia, and Europe
- 10. Cont… 2/4/2020By:Asmamaw Menelih10 both arboreal and ground dwellers Lack prehensile tail, nostrils open downwards Rhesus monkey, baboons, macaques
- 11. Hominoids 2/4/2020By:Asmamaw Menelih11 Include Great Apes and Humans Apes: Gibbons, Orangutan, Gorillas, Chimpanzee/ Bonobo Split from monkeys about 20-25MYA Larger brain size to body size ratios than other primates More flexible behavior (less instinct, more learned behaviors) Mostly larger than monkeys (except gibbons) Have long arms, short legs and no tail. Gibbons and orangutans primarily arboreal
- 12. Cont… 2/4/2020By:Asmamaw Menelih12 Gorrillas, Chimps and Humans Social behavior Primarily terrestrial Chimps more closely related to humans than gorillas.
- 13. Hominins (Hominids) 2/4/2020By:Asmamaw Menelih13 All species believed to be more closely related to human than chimpanzees Humans and our direct ancestors, since the split from chimps. Major groups: Australopithecines Paranthropsus Homo genus
- 14. Cont… 2/4/2020By:Asmamaw Menelih14 Chimps are not ancestral species !! We shared a common ancestor. Not a direct line to us !! A radiating lineage. Several hominids species co-existed. Gorillas, chimps and hominids split about 6-8 MYA. At a generous 25 year generation time: 320,000 generations ago with strong natural selection
- 16. Important hominid features 2/4/2020By:Asmamaw Menelih16 Bipedalism, upright walking Jaw shape -smaller with specialized teeth with an omnivorous diet. larger brain size, increased cerebrum Reduced size difference between sexes tool use, language, social behavior Extended parent care time- longer juvenile period More learning Reduced sense of smell Increased size of brain for vision and co-ordination with muscles Eyes are larger and directed forward
- 17. Apes: Chimps 2/4/2020By:Asmamaw Menelih17 2 species, tropical Africa Sister group to humans. Similarities to humans: We share 97% of alleles w/ chimps. Shared Many morphological features They make and use tools (simple). They have sense of self. Omnivorous. Coddling babys, breast feeding. Ability to walk bipedally.
- 19. Apes: Chimps 2/4/2020 Distinctions from Humans: Knuckle walking. Big toe has thumb-like dexterity. 50% time in trees (including sleeping). Thicker, denser body hair. Adults have more prominent brow ridge snout. Greater sexual dimorphism (less so than in Gorillas. By:Asmamaw Menelih19
- 20. II. Hominid Evolution 2/4/2020By:Asmamaw Menelih20 The species on the human branch: “hominids” (includes several genera such as Homo, Australopithecus)
- 21. Cont… 2/4/2020By:Asmamaw Menelih21 Upright posture evolved before large brains
- 22. The evolutionary relationships among huminids 2/4/2020By:Asmamaw Menelih22 Size of brain Australopithecus 400cm3 = Homo sapiens 1 300cm3 Shape of jawbone - shorter and reduced jawbone flat face, chin protrusion, change of dentition Upright bearing, bipedal locomotion → skeleton Reduced sexual dimorphism higher weight of male than female: gorilla 2x = human 1,2x • Changes in social life monogamy with long-term pair-bonding longer care of the young allows better learning and complex behaviour formula
- 23. Time scheme of Human Evolution 2/4/2020By:Asmamaw Menelih23 35 million years ago – dawn ape: anthropoid Aegyptopithecus 5-7 million years ago - diversion of humans and apes from the common ancestor 4 million years ago – ape-man: Australopithecus 2.4 million years ago – handy man: Homo habilis 1.9 million years ago – working man: Homo ergaster 1.8 million years ago – upright man: Homo erectus 0.5 million years ago – archaic Homo sapiens 0.2-0.03 million years ago – Homo neanderthalensis 0.2 million years ago – Homo sapiens
- 25. Origins 2/4/2020By:Asmamaw Menelih25 Sahelanthropus tchadensis current oldest fossil at 6-7 million years ago. Reduced canine teeth Flatter faces More upright and bipedal than other hominoids Fossils discovered in 2002
- 26. Orrorin tugenensis 2/4/2020By:Asmamaw Menelih26 Dates to 6.1-5.8 MYA Discovered in 2000 Thought to be in evergreen forest, not open grassland Oldest bipedal fossils Fossilized bones from 5 individuals Only a few femurs and teeth
- 27. Australopithecus 2/4/2020By:Asmamaw Menelih27 First “humans”: Australopithecus, about 4.4 MYA. Walked fully upright with humanlike teeth and hands. Fossil evidence of hip, hands. Skull, capacity about 1/3 modern human size. lasted 3 MY. All fossils from Eastern and Southern Africa
- 28. Cont.. 2/4/2020By:Asmamaw Menelih28 Our understanding of human evolution is constantly changing. New and different species are found and the human evolutionary tree grows more branches. One example of continuous change came in 1994 at Aramis, Ethiopia, where people unearthed fossils of a previously unknown species dating from 4.4 million years ago. This humanlike creature walked the earth nearly half a million years earlier than the oldest human ancestor identified to that point. This exciting discovery led to the identification of a new genus called Ardipithecus Ramidus. Ramidus has may chimplike as well as human features, but its position on the human family tree is still not certain. It is a mystery that still has to be solved.
- 29. The Australopithecines 2/4/2020By:Asmamaw Menelih29 1. Australopithecus Anamensis In 1995, Maeve Leaky of the National Museums of Kenya discovered some of the oldest representatives of a widely studied human genus, the australopithecines. She and her team located pieces of a bipedal hominid, 4.1 million years old she named Australopithecus Anamensis. It is an early species with very pronounced apelike teeth. Some scientists suggest that this species may have given rise to Australopithecus Afarensis.
- 30. Australopithecus Afarensis 2/4/2020By:Asmamaw Menelih30 In 1974, at Hadar, Ethiopia, Donald Johanson and his team unearthed a set of fossilized bones of a female hominid approximately 3.18 million years old. They nicknamed their discovery “Lucy”. These fossilized bones led to the identification, in 1978, of Australopithecus Afarensis, a species that may have survived almost unchanged for 900,000 years. In Lucy’s species, Johanson believed that he had found the earliest common ancestor of all later hominids. This changed with the Aramis find in 1994, and the Leaky find in 1995.
- 32. Australopithecus Africanus 2/4/2020By:Asmamaw Menelih32 Another branch of the Australopithecus family is the Australopithecus Africanus. Lived in the southern part of Africa Approximately 2.5 to 3 million years of age. There are two Africanus “off” lines. Australopithecus robustus and boisei. Australopithecus robustus A. boisei.
- 33. The Stone Age 2/4/2020By:Asmamaw Menelih33 The descendants of the australopithecines lived in the period called the Stone Age. We call the period this because most of the artifacts found from this time are mad of stone. Humans who lived in the Stone Age are generally classified into a group or genus called Homo (“man”). Most experts divide the Stone Age into three stages: 1. Paleolithic or Old Stone Age (2 million BCE-10 000 BCE) 2. Mesolithic or Middle Stone Age (10 000 BCE-8000 BCE) 3. Neolithic or New Stone Age (8000 BCE-5000 BCE)
- 34. Homo Habilis 2/4/2020By:Asmamaw Menelih34 Historians believe Homo Habilis, or “handy man”, flourished in Africa about 2.5 millions year ago. Homo Habilis were the first hominids to develop and use stone tools-proof of their ingenuity and creative ability. The brain size and presence of humanlike teeth from fossil finds suggest that Homo Habilis might have been our human ancestor. Many scientists believe that Habilis bridges the evolutionary gap between Australopithecus and Homo.
- 35. Cont… 2/4/2020By:Asmamaw Menelih35 Yet, the sequence of human ascent is still uncertain. Signs of co-existence have arisen. Co-existed with smaller-brained Australopithecus for nearly 1 MY. Australopithecus africanus was a dead end, no new lineages. Homo habilis lead to H. erectus, to H. sapiens.
- 37. Homo Erectus: upright man 2/4/2020By:Asmamaw Menelih37 Homo Erectus first appeared 1.8 MYA - 300,000 YA (about 2 million years ago). Their species name refers to the fact that they could walk completely upright, like modern humans. Only a few dozen skulls of this species have been found, notably in Africa, Java, and China. The first specimens were found in Java in 1891 and 1892. Also Called Java Man They are about 700 000 years old. Homo Erectus was the first species to use fire and the first to migrate into Europe and Asia from Africa.
- 38. Cont… 2/4/2020By:Asmamaw Menelih38 , Fossil records of Homo Erectus
- 40. Homo Heidelbergensis 2/4/2020By:Asmamaw Menelih40 Homo Heidelbergensis lived approximately 500 000 years ago. It is often referred to as Archaic Homo Sapiens because it combines features of Homo Erectus with more modern features. The first specimen was found in a Quarry in Germany in 1907. But other specimens have been found in a variety of places around the world including, Zambia, Southern Africa, Tanzania, and parts of Northern Europe as far North as England.
- 41. Cont… 2/4/2020By:Asmamaw Menelih41 Many researchers consider Homo Heidelbergensis a possible ancestor for both modern humans (Homo Sapiens) and Neanderthals (Homo Neanderthalensis) While others are still not comfortable with this label.
- 42. Homo Sapiens 2/4/2020By:Asmamaw Menelih42 The species name, Homo Sapiens, means “man who thinks”-an appropriate title for the species that formulated the spoken language and developed more sophisticated tools. The most ancient find was discovered in Hungary in 1965, dating from about 450 000 to 400 000 years ago. Other remains of Homo Sapiens have been found in England, Germany, and France. These bones date from approximately 250 000 years ago, the period between the third and fourth ice ages.
- 43. Cont… 2/4/2020By:Asmamaw Menelih43 There are two types of Homo Sapiens: 1. Neanderthals, or Homo Neanderthalis, and 2. Modern Human, or Homo Sapiens
- 45. The Modern Human 2/4/2020By:Asmamaw Menelih45 About 40 000 years ago, modern humans moved into Europe armed with the skills to make clothing, better shelters, and more efficient hearths. Nineteenth-century scientists named these newcomers Cro-Magnon people after the French rock-shelter where three anatomically modern skeletons were discovered in 1868. Cro-Magnons were Homo Sapiens who evolved in Africa and slowly pushed their way into Europe. They developed the ability to endure colder climates, even climates as cold as those found in Iceland or Greenland.
- 46. Cont… 2/4/2020By:Asmamaw Menelih46 Cro-Magnon people were about as tall as modern northwestern Europeans. They also had many of the same facial and cranial features as modern northwestern Europeans. Eventually, their successors moved into Asia. About 30 000 years ago, they crossed the Bering Strait after the retreat of the ice and entered the Americas. Others reached Australia. With this migration, our modern human ancestors spread throughout the world.
- 47. Origins of the “wise-man”, Homo sapiens 2/4/2020By:Asmamaw Menelih47 Three Models for the Origin of Humans 1. Multiregional model Modern humans evolved in many parts of the world from regional descendants of Homo erectus, who dispersed from Africa between 1 and 2 million years ago. 2. Monogenesis model (“out of Africa” model) Only the African descendants of Homo erectus, who dispersed from Africa just 0.1 million years ago, gave rise to all the diverse populations of modern humans. All other regional descendants of Homo erectus, including Neanderthals, became extinct without contributing to the gene pool of modern humanity.
- 48. Cont… 2/4/2020By:Asmamaw Menelih48 3. Intermediate model: Modern humans may be the result of migration out of Africa as well as some genetic contribution from non-African archaic groups.