Science Advancement Conference: Ancient excrement is opening up a whole new world of information about early humans.
Fossilised poo is a veritable goldmine of data, providing DNA samples from the defecator and from the foods they ate, information about the plant and animal species that lived at the time and whether fellow cavemen were included on the menu.
This new science is described as "palaeoproteomics" by Prof Hendrik Poinar of McMaster University, who specialises in getting bimolecular samples from the fossil record. He described his work with fossilised faeces, known as coprolites, and other cave floor detritus during a session at the American Association meeting in Seattle.
"If you take sediments from a cave the majority is faecal samples from animals that visited the cave," he said. With coprolites "you can identify the defecator quite easily," he added.
"I think of coprolites as sandwiched molecular information." The process involves using new techniques, including application of a drug called PTB to extract proteins. The drug is meant for use in diabetes and is currently undergoing phase III human trials.
Yet it is also ideal for extracting proteins, DNA and other samples from fossilised wastes. "It made samples that didn't give any DNA give DNA," Prof Poinar said. Proteins are somewhat easier to find in ancient samples because they "survive much longer than DNA", Prof Poinar said. Yet the proteins can still give genetic details that can help identify species and support comparisons to establish when certain traits became established in a population.
The fossils date to a time when Neanderthals and Cro-Magnon man shared cave sites in many parts of the world. Palaeontologists are deeply interested to know whether or how these two species interacted, perhaps mating or eating one another for dinner.
This information simply has not been available until now, Prof Poinar said.
"Two years ago this would have been a pipe-dream." Now he is extracting genetic information from 9,000-year-old coprolites left behind in caves by the ancestors of the native Americans living in what is now Texas.
"The cave sites are fantastic," he said. They were used by early humans but also animals to shelter from the weather. All left behind excrement, food wastes and bones, grass or leaf bedding and all manner of stuff as they lived out their lives.
This in turn built up into sediments and fossilised, surviving very nicely by being out of the weather and in conditions of stable temperature and humidity. The samples can be radiocarbon dated and then the molecular data is extracted.
That information includes details about climate and the flora and fauna near the cave, parasites and illnesses , information about diet and the genetic details of these ancient cave people.