The deposits collected in a distant relative of the elephant’s communal toilets are challenging some long-held beliefs about the climate of the Earth’s dry regions. That’s not to equate existing science with animal dung, or even cite some quasi-mystical prediction method. Instead, Brian Chase from the Institute of Evolutionary Sciences in Montpellier, France, and his colleagues commenced a five-year European funded project on Monday to study the chemical composition of the toilets or “middens” of the rock hyrax.
The possibility of using middens for scientific analysis comes because populations of hyraxes use the same ones for thousands of years. However, despite being part of the same family as the elephant, hyraxes look more like guinea pigs, and live in locations that present already unusual-sounding research with even more improbable challenges. “With few exceptions middens are found high on cliffs, often under large overhangs, which makes access particularly difficult,” Chase explains. “Add to this an assortment of power tools, loose rock, poor protection, and the logistics of rigging a system that will allow you to safely remove and lower a 50 kg block of dense, but surprisingly fragile urine, and it is fair to say that the entire enterprise takes a rather special skill-set.”
Chase is following this difficult research path because chemically analysing the deposits it returns are sensitive measures of the palaeoclimate – or prehistoric climate – of Earth’s driest areas. “Whereas the world’s temperate regions are full of lakes and wetlands that serve as wonderful sediment traps, where long, largely continuous palaeoenvironmental records may be preserved, drylands are notably lacking in such features,” he explained. “There is an acute lack of information from these regions, which sparked my interest for the sheer challenge and sense of exploration and contribution.”
Filling the data gap
“Dryland regions are particularly sensitive to climate change, presenting an ideal opportunity for studying the natural variability of climate systems,” Chase continued. “More importantly, as drought-prone regions, it is critical that we better understand how climate change affects their vegetation and hydrology so that sound and appropriate management decisions can be made for the future.”
Having initially tried to establish direct dating methods based on sand dunes as “proxy” measurements of historical climate in these neglected areas, Chase was ultimately frustrated. However, in his determination to chart dryland history, he was inspired to turn to hyrax middens by the findings of Louis Scott from the University of the Free State, South Africa.
“Composed of successive layers of fossilised urine and faecal pellets, preliminary studies have shown hyrax middens to be rich archives for fossil pollen records, some of which span at least the last 45,000 years,” Chase explained. Scott used methods on the hyrax urine that he had used on pack rat middens in the US, leaving room for hyrax-specific methods to be developed, and for a more thorough study. “While the promise of hyrax middens was apparent, their full potential had yet to be explored,” Chase said.
Since then, Chase and others have discovered a range of new climate proxies preserved within hyrax middens that have allowed him to join forces with Scott in the latest study, aptly named “HYRAX”. “The goal of HYRAX is to revolutionise our understanding of environmental change in southern Africa,” he said. It will do this by developing sites, proxies and methods that will allow the team to collect, analyse and integrate environmental data from the last 50,000 years.
Early results – treat with caution
Although their research remains in its early stages, hyrax proxies have already suggested that the direct influence of the sun has less influence on tropical atmospheric and ocean circulation than previously thought. Instead, the system appears to be more influenced by cycles of warming and cooling nearer the poles.
While Chase warns that using such data to speculate on what may happen in the future is “always difficult, and in light of the current debate dangerous,” he suggests that current climate change might stop the areas he is studying from being quite so dry. “Data I have from southern Africa suggests that warmer climates in regions influenced by tropical systems will become wetter,” Chase says.
“In the Kalahari and Namib Desert this could result in something akin to the ‘greening of the Sahara’ that occurred in the early Holocene, and has been suggested as a potential scenario for a warmer future. But it must be remembered that the data we have is insufficient to support any such claims with reasonable certainty. Hopefully our new project will clarify this situation and provide a sounder basis for the development of appropriate management.”
Finally, I asked Chase to help me with the purpose of my blog – to provide a simple explanation of climate change – but unfortunately, instead he could only provide me with a sobering reminder of the difficulty of my task. “I wish I, or anyone, could, but I personally don’t believe that a simple explanation of ‘climate change’ presently exists,” the researcher said. “Many people who suggest otherwise are, while often with good intentions, trying to sell something.”