Related by context. Frequent words. (Click for all words.) 74 radiocarbon dating 63 isotopic 58 lake sediments 54 Pliocene 54 fossils 53 sediment cores 53 atmospheric carbon dioxide 52 sediments 52 fossil 50 nitrogen fixation 50 Eocene 50 radioactive decay 48 Neandertals 48 atmospheric CO2 48 mineralogy 48 abundances 48 strontium 48 Quaternary 48 biogenic 48 geochemical 48 carbon isotope 47 stable isotope 47 mtDNA 47 mitochondrial DNA 47 Archaeopteryx 47 pottery shards 47 sediment samples 47 Carboniferous 46 apatite 46 measurements 46 mammoths 46 volcanism 46 Medieval Warm Period 46 CO2 concentrations 46 Cretaceous 46 Pleistocene 46 Ordovician 46 Oetzi 46 glaciation 45 theoretical calculations 45 Neanderthal DNA 45 journal Geology 45 paleo 45 hominid 45 diatom 45 Neolithic 45 basalts 45 chemical composition 45 Paleolithic 45 megafauna 44 sediment 44 geologic 44 geochemistry 44 stalagmite 44 melanosomes 44 Precambrian 44 spectrometry 44 Late Cretaceous 44 hominids 44 Australopithecus 44 Holocene 44 plate tectonics 43 diatoms 43 atmospheric concentrations 43 archaeologists 43 fossilized 43 astronomical observations 43 evolutionary biologists 43 sedimentary rocks 43 paleoanthropologist 43 archeologists 43 palaeontologists 43 aerosol particles 43 Homo habilis 43 glaciologists 43 computer simulations 43 Ardipithecus 43 lithosphere 43 iron oxides 42 spectroscopic 42 theropods 42 Homo erectus 42 geological 42 paleontologists 42 Paabo 42 hypothesis 42 mineralogical 42 olivine 42 Oligocene 42 scanning electron microscope 42 anatomically modern 42 Computer simulations 42 Homo sapiens 42 Cretaceous Period 42 high temperature superconductivity 42 Neanderthals 42 Geochemistry 42 scientists 42 reanalysis 42 Nature Geoscience 41 Geochemical