It is my pleasure to introduce today Professor Rainer Grün, a world-renowned geochronologist and Professor of Archaeochemistry at Griffith University! Rainer is the former Director of the Australian Research Centre for Human Evolution and is an acknowledged leader in the field of electron spin resonance (ESR) and uranium-series (U-series) dating. His work has contributed immensely to our understanding of the timing of human evolution, for example through the development of non-destructive dating methods and the discovery of new, surprisingly young, dates from Broken Hill skull from Zambia, which revealed that Africa and Eurasia were inhabited by a whole range of hominin species just a few hundred thousand years ago!
What are your research interests and your particular area of expertise?
I’m a geochronologist and the main thrust of my research relates to further developing dating techniques, in particular U-series and ESR dating. This requires expertise in geochemistry for U-series and radiation physics for ESR. In recent years, I mainly focussed on developing virtually non destructive dating, which is essential for the analysis of ancient human remains. I’ve also ventured out to work on the use Sr isotopes for the reconstruction of human migrations and provided a Sr isotope map for France. Another side track is working on palaeothermometry, which is a tool that can assess how fast valleys erode and estimate the denudation rates of mountain ranges.
What originally drew you towards geochronology and human evolution?
I was lucky to spend my first postdoctoral fellowship at McMaster University with Prof Henry Schwarcz. He got me interested in archaeological applications. In December 1986, I attended the International Colloquium L’Homme de Neanderthal in Liege, where I met Chris Stringer with whom I struck a lifelong friendship. He really got me into palaeoanthropological dating applications. Jean-Jacques Hublin attended the same meeting and our collaborations started at the same time.
What was your PhD topic? How did you find your PhD experience?
My PhD was entitled “Contributions to ESR dating”. It was pretty much a random selection of experiments on the underlying principles of ESR dating and applications on whatever samples I could get hold of. As an undergraduate student, I was not very focussed on studying. I held several pinball machine records in the pubs around the Department of Geology in Köln. I thought my fate was becoming a taxi driver. However, once I discovered research during my Diploma thesis work, I got hooked. I worked pretty much around the clock and did my PhD in less than two and a half years.
After your PhD, what positions have you held and where?
I was a postdoc fellow at McMaster University from mid 1985. In 1987, Ann Wintle asked me whether I was interested to take over her thermoluminescence lab at Cambridge. In the late 80s I met John Chappell who was the professor for Biogeography and Geomorphology at the ANU in Canberra. He encouraged my to apply for the directorship of the radiocarbon dating laboratory, which I commenced in early 1992. I stayed at the ANU for the next 23 years until I was offered to set up what later became the Australian Research Centre for Human Evolution at Griffith University in Brisbane.
What current projects are you working on? Where do you hope these go in the future?
I am close to retirement. I have several projects that I pursue, in particular to understand the diffusion processes of uranium into bones and teeth and to see whether there are uranium concentration dependent correlations with the alpha efficiency in tooth enamel. I also continue to collaborate with a wide network of researchers on the direct dating of human remains. This work is presently divided up between Mathieu Duval who does the ESR analysis and I carrying out the U-series work.
What project or publication or discovery are you most proud of?
They relate to original ideas. Truthfully, one does not have many of those in ones career. Two of the publications will be very obscure for the readers of this website and they relate on the possibility of dating mollusc shells without the need to measure the external dose rate, the other one is on the palaeothermometry of the Eldzurtinsky Granite. The most important idea relating to palaeoanthropology was combining U-series and ESR systematics for the simultaneous modelling of the age of a tooth as well as the uranium uptake history of its various dental tissues. This publication is the underpinning of all dating applications of teeth using these methods.
What do you think is the most revolutionary discovery in human evolution research over the last 5 years?
Of course, the discoveries of several new human species such as Homo naledi and Homo luzonensis as well as the Denisovans. In particular, DNA work has brought a completely new dimension to our understanding of the complexity of human evolution: the interbreeding of what was thought to be different species, and the time depth of the occurrence of the various species.
What is the best thing about your job and what is one thing you would change if you could?
I had a very satisfactory career and don’t think I’d change a thing, mistakes, warts and all. Considering my somewhat forceful driving style, I don’t think I would have made a good taxi driver.