Environment and excavation: Pre-lab impacts on ancient DNA analyses

Ancient DNA (aDNA) analyses enjoy an increasing role in palaeontological, archaeological and archaeozoological research. The limiting factor for aDNA studies is the degree of DNA preservation. Our study on 291 prehistoric cattle remains from Europe, the Near East and North Africa revealed that DNA preservation is mainly influenced by geographic and climatic conditions. Especially in hot climates, the preservation of sample material is generally low. We observed that these specimens are prone to further degradation and contamination during and after excavation. We give a description of the main caveats and a short guideline for adequate sample handling in order to facilitate the cooperation between archaeologists and geneticists and to improve the outcome of future research.