An understanding of the structural complexity of mineralised tissues is fundamental for exploration into the field of diagenesis. Here we review aspects of current and past research on bone and tooth diagenesis using the most comprehensive collection of literature on diagenesis to date. Environmental factors such as soil pH, soil hydrology and ambient temperature, which influence the preservation of skeletal tissues are assessed, while the different diagenetic pathways such as microbial degradation, loss of organics, mineral changes, and DNA degradation are surveyed. Fluctuating water levels in and around the bone are the most harmful for preservation and lead to rapid skeletal destruction. Diagenetic mechanisms are found to work in conjunction with each other, altering the biogenic composition of skeletal material. This illustrates that researchers must examine multiple diagenetic pathways to fully understand the post-mortem interactions of archaeological skeletal material and the burial environment.

Genome-wide analysis of 67 ancient Near Eastern cattle, Bos taurus, remains reveal regional variation that has since been obscured by admixture in modern populations. Comparisons of genomes of early domestic cattle to their aurochs progenitors identify diverse origins with separate introgressions wild stock. A later region-wide Bronze Age shift indicates rapid and widespread introgression of zebu, Bos indicus, from the Indus Valley. This process was likely stimulated at the onset of the current geological age, ~4.2ka, by a widespread multi-century drought. In contrast to genomewide admixture, mtDNA stasis supports that this introgression was male-driven, suggesting that selection of arid-adapted zebu bulls enhanced herd survival. This human-mediated migration of zebu-derived genetics has continued through millennia, altering tropical herding on each continent.

• The human petrous bone has different histomorphology from other skeletal elements • No microscopic focal destructions observed in human petrous bones • Only few merged osteocyte lacunae may indicate some limited microbial presence • Generalized destruction is linked with decreased levels of endogenous DNA • Dissolution/recrystallization of bioapatite is linked with loss of endogenous DNA

Highlights d Bronze Age (BA) Helladic, Cycladic, and Minoan genomes from the Aegean were sequenced d 3,000 BCE Aegeans are homogeneous and derive ancestry mainly from Neolithic farmers d Neolithic Caucasus-like and BA Pontic-Caspian Steppe-like gene flow shaped the Aegean d Present-day Greeks are genetically similar to 2,000 BCE Aegeans from Northern Greece

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