Outline 22: Hominid Fossil Record
Human ancestors
A.=Australopithicus Assumed direct lineage to modern humans Lots of names but pattern is clear that Homo evolved from an australopithecine over 2 m.y. ago.
Babcock textbook Collecting hominid fossils in East Africa Using Stratigraphy and Radiometric Dating of volcanic ash beds to date hominid fossils Hominid Jawbones from Ethiopia Sahelanthropus tchadensis, 6.5 MY old Sahelanthropus tchadensis, 6.5 MY old Gorilla – female on left, male on right; note the sexual dimorphism Orrorin tugenensis – the sum total of specimens Ardipithecus ramidus, 2009
Australopithecus anamensis The Australopithecines
• Ardipithecus: oldest definite bipedal ancestor, over 4 M.Y. old • Australopithecus: the gracile australopithecines • Paranthropus: the robust australopithecines Fossil Species
• Ardipithecus ramidus: 4.4 MY, teeth, jaws and bone fragments suggest it is a hominid, not a pongid. • Australopithecus afarensis: 3.8-3.0 MY based on good fossils. Clearly a bipedal animal based on bones and fossil footprints. Bipedal Footprints of Australopithecus in Lithified Volcanic Ash 4 MY old from Tanzania. Found by Mary Leakey.
Australopithecus couple making footprints in volcanic ash Jawbones of Australopithecus afarensis Fossil remains of “Lucy”, the most complete specimen of Australopithecus afarensis. An adult skull, A. afarensis. The spinal cord opening is underneath the skull. Pelvis of Australopithecus afarensis Reconstruction of Australopithecus afarensis Face-to-face with A. afarensis A troop of A. afarensis feeding on tubers in the forest. A. afarensis family unit crossing the savannah. Fossil Species
• Australopithecus africanus: 2.8-2.5 MY • Robust australopithecines: Paranthropus aethiopicus: 2.6-2.2 MY P. robustus: 2.0-1.2 MY P. boisei: 2.6-1.0 MY The Taung Child, A. africanus Skull of Paranthropus boisei Paranthropus aethiopicus Paranthropus aethiopicus Justus Erus found the fossil
Kenyanthropus platyops, 3.5 MY old from Kenya Kenyanthropus rudolfensis or Homo rudolfensis?
Or Darth Vader? Fossil Species
• Homo habilis: 2.5-1.6 MY • H. erectus: 1.8 MY- 25,000 yrs? Java man Peking man • H. sapiens: archaic vs. modern Skull of Homo habilis H. rudolfensis, H. habilis, and P. boisei. Hominids in East Africa around 2 MY ago. Phylogeny 2000. One of many hypotheses. Homo erectus from Indonesia, Java Man Skull of Homo erectus from China Peking Man Skeleton of Homo erectus, Turkana Boy from Kenya H. erectus skull of Turkana Boy The face of Homo erectus Homo erectus using fire to sharpen spears Homo sapiens?
• Archaic H. sapiens or unique species? H. antecessor: 800,000 years old H. heidelbergensis: 500,000 years old H. neandertalensis: 200,000-32,000 years old • Currently all thought to be unique species. Homo antecessor from Spain, 800,000 years old Homo heidelbergensis, 500,000 years BP Neanderthal skull, Spain Fleshing out a Neanderthal skull Neanderthal skeleton, Germany Shanidar Cave, Iraq: Neanderthal burial, 50,000 yrs. BP Shanidar Cave, Iraq: Neanderthal burial, 50,000 yrs. BP Did Neanderthals have naked skin like we do? What would the Theory of Neoteny say? Reconstruction of Neanderthal child from Gibraltar, Spain, 30,000 years B.P. How scientists recreated Neanderthal man
http://www.bbc.co.uk/news/science-environment-19960748 2010: Genetic studies of Neanderthal bones indicates that between 1-4% of modern human DNA is from Neandertals. Suggests interbreeding around 60,000 years ago.
30 ky
1%-4% DNA
500 ky
http://news.bbc.co.uk/2/hi/science/nature/8660940.stm 2010: Genetic studies of Neanderthal bones indicates that between 1-4% of modern human DNA is from Neandertals. Suggests interbreeding around 60,000 years ago.
Fig. 1 Samples and sites from which DNA was retrieved.
R E Green et al. Science 2010;328:710-722 Did light colored skin and hair come from Neanderthal genes?
http://www.cbsnews.com/news/modern-humans-more-neanderthal-than- once-thought-studies-suggest/ Homo sapiens
• modern H. sapiens: first appearances East Africa: 195,000 years ago Middle East: 90,000 years ago Australia: 50,000 years ago Europe: 32,000 years ago Americas: 20,000 years ago Homo sapiens, Israel, 90,000 yrs BP FYI: Abraham lived only 4,000 yrs BP Cro-Magnon man from France, Homo sapiens, 28,000 years old Homo floresiensis, a hobbit-size human from Flores Island, Indonesia, 18,000 BP
Modern human Homo sapiens (Cro-Magnon people) drew the cave art in France and Spain about 17,000 years ago. Lascaux, France, cave art Other rock paintings Life in the late Stone Age, which ended at different times on different continents. The invention of farming, plus domestication of animals, started civilization. Evolution of Modern Humans Two Theories: • Out of Africa: all modern humans descended from a single population. Racial differences have very recent origins. • Multiregional Theory: modern humans evolved from local populations of H. erectus at several places in the Old World. Accounts for the racial differences in modern humans.
How far back in time did the modern races diverge from a common ancestor? Tree DNA studies Diagram show the of Genetic Similarity common ancestor of all humans lived in Africa about 170,000 years ago