Environmental DNA (eDNA) is obtained from samples such as sediments, ice or water and can provide scientific sleuths with tantalizing clues about past and present biodiversity.
Smith et al. (2015) used sealed sediment cores to combine evidence from microgeomorphology, microfossils and sedimentary ancient DNA (sedaDNA) to reconstruct the biotic changes that occurred during the occupation of the present day Isle of Wight during the Mesolithic to Neolithic transition in which a hunter-gather economy was replaced by agriculture.
Sequence data is traditionally reliant upon discrete sources of material that has come from an individual plant or animal. But, individual plants and animals also leave behind extracellular DNA in the environment.
By using ancient DNA, Smith et al. (2015) detected DNA sequences associated with wheat as well as the proportion of these sequences in the plant profile increased as the soil samples were extracted from sedimentary layers closer to the present day.
As highlighted by Larson (2015), the methodology and results from studies like these are intriguing for arm-chair time traveling, but go beyond that in potentially challenging the chronology of historical events and tracing the dispersal of plants and animals.