Ruairidh Macleod

Living things have a tendency to be ephemeral, and this is especially true for the large majority of cases where there aren’t bones or shells to be preserved in archaeological or geological contexts. Nonetheless, it is possible to study the genetic evolution of our more recent antecedents by analysing the DNA that was once part of the genome of the microbes, plants, from environmental substrates like soil, even when there are no physical remains present. Fragments of ancient DNA can be analysed from buried sediments, deep ice-cores and centuries-old layers of ambergris whale fecaliths (for example), as well as old bones, teeth and plant remains.  In my research, I’m particularly interested in how preserved DNA typically represents a diverse mixture of dead things: these DNA sequences are palimpsest of what’s left from all the varied life-forms that a sample might have come in contact with. For example, tooth samples can preserve both a person’s own DNA and that of the microbes that live in their mouth, while lake sediment cores can preserve DNA from the changing communities of plants and animals nearby over thousands of years. I’m particularly interested in developing approaches to integratedly study this information from across ecosystems changing through time. This focuses on how humans have disrupted ecosystems at vastly different scales, ranging from trans-continental terrestrial biomes to the commensal microbiomes within our mouths. I’m especially interested in the unintended consequences of this disruption, like outbreaks of diseases jumping from animals to humans (zoonoses)