Urine offers up climate change insight

Urine from the rock hyrax which has crystallised over thousands of years is providing a previously untapped resource for studying climate change.

The hyrax – common in Namibia and Botswana – is related to the elephant but looks like a guinea pig and uses specific locations as communal toilets, some of which have been used by generations for thousands of years. Now an international team of scientists are using stratified accumulations of urine – known as middens – to see what the hyrax used to eat.

“In order to study past environmental changes scientists typically acquire samples from deposits laid down in bog or lakes, within which organic matter which can be dated is preserved,” said Dr Andrew Carr from the University of Leicester, “But in dryland environments such as southern Africa this isn’t possible. Fortunately it seems that hyrax urine preserves organic matter over timescales of tens of thousands of years, which provides remarkable insights into past environmental changes within the hyrax habitat.”

Using forensic techniques, Carr and his colleague Dr Arnoud Boom were able to identify individual organic molecules preserved in the middens, which were obtained by research leader Dr Brian Chase. These molecules include compounds produced by the animal’s metabolism and plant-derived molecules which went through its digestive system. These molecules provide clues to the kind of plants the animals were eating and the sort of environmental they were living in.

The biomarkers can be used to reveal how the climate of the region has changed over the last 30,000 years and is accurate to a few centuries, maybe even decades.

“The middens are providing unique terrestrial records to compare against nearby deep ocean-core records, allowing us to think in much details about what drives African climate change,” said Carr, “This is a very dynamic environment, and it appears that the region’s climate changed in a complex manner during and after the last global ice age.”