Chronology

AMINO ACID RACEMISATION-BASED CHRONOLOGY

Not only can the protein in enamel help trace past evolutionary pathways, its predictable breakdown also holds the key to understanding the timescales of these changes. A mosaic of early hominin lineages across Africa is becoming apparent, and accurate chronology is critical to tie these together, and to understand the links to their palaeoenvironment and climate. Establishing an accurate chronology is imperative for our understanding of mammalian (including hominin) evolution (taxonomy and phylogeny), and for decoding any relationship to biogeography, environmental change and global climate. Tephra stratigraphy and its associated Ar/Ar dating allows chronologies to be developed beyond 50 ka in the regions that have had active vulcanism (i.e. parts of the East African rift valley). Beyond the tectonically active zones there are an assortment of dating methods (e.g. U/Th & U/Pb on speleothems in caves), yet biostratigraphy/biochronology is the most widely applicable, despite its imprecision. This lack of chronological control means that the enormous potential of the deeper fossil record is untapped. We will exploit the recent breakthrough made in using protein degradation to date tooth enamel and apply them to regions where the palaeoenvironmental record can help us understand the sensitivity of Africa’s hominin fauna to climate changes. Dating enamel protein has the enormous advantage of providing a direct date on mammalian teeth, the key fossils of interest. PROJECT 14 will track the degradation pathways of enamel proteins (providing insights into mechanisms and processes which will be helpful to multiple PUSHH projects), while the combined methods (dating and species i.d) will provide value to the vast quantities of excavated tooth material currently too fragmentary for conventional morphological identification.