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Early Humans: Meet the Ancestors

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1 Early Humans: Meet the Ancestors
2. Archaeological Evidence and the Limits of Knowledge

2 Objectives Look at the scientific investigative tools Stratigraphy
Archaeological dating methods Comparative Anatomy of Fossils DNA and Isotope analysis Artefact and Ecofact Evidence Consider the security of our interpretations.

3 Charles Darwin Origin of Species, 1859 The Descent of Man, 1871
Cartoon from “The Hornet” satirical magazine 1871

4 Stratigraphy Provides relative dating – separating the remote past into horizons of greater and lesser age. Boxgrove, England

5 Fauna Assemblages – Environmental Dating
Boxgrove excavation era of strata indicated by animal bone assemblages Extinct rhinocerous, Stephanorhinus hundsheimensis Period when Britain had a climate like modern Africa Sites can be given sequence relative to each other but not a date by this method.

6 Radio Carbon Dating Invented c. 1950
Based on the principle that C14 decays at a predictable rate Age calculation made by examining ratio of C14 and C12 Relatively short half life c years makes it accurate, but limits its range to about the last 40,000 years

7 Lascaux, S France Accelerator Mass Spectroscopy – very small samples.
C14 dating of cave painting, targeting carbon based pigments Images date to kya Some images refreshed over thousands of years

8 Potassium - Argon Dating
Less accurate but much greater dating range – suitable for the earliest hominids Used to date layers of volcanic rock Noble gas Argon 40 released when rock molten Any Argon 40 present must have derived from Radio Decay of Potassium

9 Laetoli, Early Hominid Footprints
Volcanic ash Potassium – Argon suggests 3.6 mya

10 Uranium Series Dating Based on ratios between radio active Uranium isotopes and daughter products Uranium products are soluble in water. Thorium and Protractium products are insoluble in water. Calcareous deposits like limestone therefore start their existence with no Thorium or Protractium present.

11 Uranium 238 Series Uranium 238 4.51 billion years
Uranium ,000 years Thorium ,200 years Radium years Radon days Lead years Polonium days Lead stable

12 Uranium 235 Series Uranium 235 713 million years
Protractium ,400 years Thorium days Radium days Lead stable

13 Vartop Cave, Romania Limestone cave Neanderthal occupation dated to 62kya to 97kya by U-series. Footprints Suggests an individual 1.46 m tall

14 Cave Art Creswell Crags, Derbyshire
Engraving Church Hole Creswell Crags U-series sampling of flowstone suggests pre- 12,800 BP

15 Equilibrium Level As levels of Thorium 230 increase rate at which it is destroyed approaches rate at which Thorium 230 is created by decay of Uranium 234.

16 Comparative Anatomy of Fossils
Comparison of cranial capacity

17 Incompleteness Australopithecus Afarensis Best specimen “Lucy”
Only 40 % complete No formal burials from this period. Most bodies dismembered and scattered by scavengers

18 Turkana Boy H. erectus, 1.5 mya Very narrow spinal column
Lacked fine control of diaphragm Implications for speach Other specimens fall with range of modern humans Might be an individual with genetic defect.

19 New Species or or Diseased Individual
Recent discovery of a new “hobbit” species contested H. floresiensis skull compared to modern human with the genetic disorder microcephaly. H. floresiensis frontal and temporal lobes highly developed

20 Dimorphism in Australopithecine
Suggested Australopithecine dimorphism as compared to modern humans Hominids of different sizes now thought to represent different contemporary species

21 Ancient DNA Cheddar Gorge Late Palaeolithic skull 1911
DNA recovered 1990’s Adrian Targett – descendant living few miles from find site Fears of contamination from modern DNA

22 Age Estimation Tooth Eruption can give age at death in modern humans very accurately Age can also be estimated from the state of fusion of bones of the skull and limbs

23 Errors in estimating age
Australopithecene infant “Taung’s Child” Age by comparison with humans 7 years Age by comparison with chimps 3 years

24 Comparative Anatomy - Teeth
Nakalipithecus nakayamei jaw, Kenya, c 10mya Homo erectus c. 1 mya Broad grinding teeth indicate a fibrous plant diet, smaller teeth of H. erectus indicate an omnivore's diet – high value foods like fruit and meat.

25 Isotopes and Diet Fractionation of stable isotopes can idicate the origin of food sources. Ratios of C13 and C12 different for terrestrial and marine diets Mesolithic shell midden with human remains, Oronsay, Inner Hebrides Suggest protein almost entirely from fish, shellfish and marine mammals

26 Assessing Prey Species
Butchered animal bone, Boxgrove Homebase site – resources brought back to a central base. Sequence of cuts and knaw marks suggests human kill later scavenged by other large predators,

27 Tool Use Modern chimps demonstrating tool use.
Baringo Basin tools, Kenya 2.6 mya Earlier tools almost certainly being used but impossible to distinguish from naturally broken material

28 Inorganic Artefacts Clacton-on-Sea spear
Sharpened and fire hardened shaft Earliest wooden artefact, 290 kya Associated with Homo heidelbergensis. Earlier artefacts simply have not survived.

29 Problems Interpretation rests on very partial survival of evidence.
Measuring errors – complex procedures to measure very small differences in composition Sampling errors – contamination Most interesting statements rest on chains of inference All data is subject to a degree of doubt

30 Piltdown Man Hoax Discovered 1908 gravel pit East Sussex by museum Charles Dawson Published in the Journal of the Geological Society 1912, named Eoanthropus dawsoni Exposed by fluoride absorption test 1949, published 1953 in “Time” Medieval human skull Orang-utan jaw and chimpanzee teeth

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