John Grattan of the University of Wales has a paper in a recent issue of Quaternary International on the impacts of volcanic eruptions on past societies, prehistoric and historic alike. It's a really level-headed discussion of the inferences that can actually be made about just how un-catastrophic most of these events are likely to have been. Of course, he doesn't deny the dramatic influence volcanic eruptions have had on certain past societies, especially in the immediate vicinity of the volcano. But he does emphasize how the impact of such events was, in all cases, mediated by the socio-economic, political and/or ecological context of the groups affected by volcanism, no matter how dramatic.
Equally important, in my opinion, is his demonstration that the supposedly 'tell-tale' repercussions of volcanic eruptions on human socioecosystems (e.g., famines, unusually harsh weather plague and pestilence, crop failure) have been documented historically even in periods during which there was no recorded "eruptions of note." In 9th Century Europe, such calamitous events appear to have occurred at an average frequency of fully one every three years, without there being any need to invoke volcanism as a prime mover. Perhaps the most important point that Grattan makes in his paper is that, by and large, the human response to catastrophic events has always been one of adaptation rather than annihilation. In other words, people were not just passive witnesses to the furies of the earth, but - unsurprisingly - took matters into their own hands to escape destruction by natural forces, or at the very least enact social, economic or technological strategies to more easily bear their adverse consequences. That being the case, people invoking volcanism as a prime mover for biological, cultural and/or technological changes in the past need to be very careful in establishing credible cause-effect relationships in order to support their arguments. This is especially true for those periods of the past for which our understanding of the chronology can still be quite shaky, such as the Late Pleistocene (e.g., Ambrose 1998). Given that volcanic deposits are easily characterized chemically and can be dated much more precisely than many other kinds of prehistoric deposits, it is also imperative to provide empirical data to support the correlation of a volcanic tuff in archaeological context to a specific volcanic eruption. Impressions and 'general chronostratigraphic agreements' are not enough to support scenarios invoking eruptions as significant agents of prehistoric change. And subsequently, it is crucial to account for the innate adaptability of human groups rather than postulating widespread societal and demographic collapse.
Grattan's paper is part of a special issue of Quaternary International entitled “Dark nature: responses of humans and ecosystems to rapid environmental changes,” edited S.A.G. Leroy, H. Jousse and M. Cremaschi. It includes a number of interesting papers focused mainly on more recent periods, but it does a very good job of demonstrating how archaeology can provide important information on issues of climate change and human responses to them, which are increasingly relevant today and how the discipline is uniquely positioned to serve as a productive meeting ground or mediator between the historical and natural sciences (van der Leeuw and Redman 2002). Good stuff.
Ambrose, S. H. 1998. Late Pleistocene human population bottlenecks, volcanic winter and differentiation of modern humans. Journal of Human Evolution 34:623-651.
Grattan, J. 2006. Aspects of Armageddon: an exploration of the role of volcanic eruptions in human hitsory and civilization. Quaternary International 151:10-18.
van der Leeuw, S. E., and C. L. Redman. 2002. Placing archaeology at the center of socio-natural studies. American Antiquity 67:597-605.
130,000 year old Californians?
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