Thursday, June 14, 2012

From mythological approaches to independent geological expertise

In former times, things used to be very different, and for most of human history the observation of geological phenomena and the acquisition of geological expertise was intimately connected with religious ideas. Earthquakes and volcanoes, towering mountains and conspicuous rock formations, fossils and ore veins were regarded either as due to direct divine action and intervention or as manifestations of the divine itself (Mazadiego et al.; Barbaro). It was God (or Gods), who had created the Earth as ‘home’ for humans, providing the necessary resources (animals and plants, but also water, rocks and metals), or who might be suspected to exert punishment on sinners by means of natural disasters (Kölbl-Ebert 2005; Udias on earthquakes). Although accepting flint and pyrite in prehistoric time, or later copper and other ores, to be gifts of divine providence (Norris) is some sort of explanation for their existence, that assumption was clearly not sufficient to enable adequate strategies for the search for new deposits to be devised. Observational skills and arrangement of observations according to rules and guidelines (involving the formulation of theories) were required, and eventually such knowledge was accumulated and became part of the craft knowledge of miners.
Also, from an intellectual point of view, invoking divine action as a general and all-fitting explanation of phenomena was unsatisfying for an intellectual, and even for the devout theist who would like to know how God ‘did it’. After all, curiosity is a decidedly human trait. For this more theoretical part of ‘geological expertise’, the late Medieval and Renaissance intellectual world turned to the remnants of much older knowledge, that of the antiquity, which apparently had been a golden, better and much more knowledgeable age, judging from the ruins that were still around. Why not trust the explanatory power and authority of ancient texts (including the Bible) that had been produced by these obviously advanced civilizations?

This intimate link between early geo-theory and Christian philosophy proved to be very fruitful for some time, because the Christian tradition of visualizing the history of humans on Earth from the creation, via global revolutions such as the biblical Flood up to historical times (Rudwick 1992; Magruder) and the Judaeo-Christian sense of a finite Earth history (Rudwick; see also Rudwick 2005) prepared the ground for accepting the Earth’s different strata as testimony to the development of our globe through time. It was this religious, theological framework from which the early geology started to evolve, and that provided the tools used in popularization of the new science of the seventeenth century. It is understandable why, for example, geological phenomena such as erratic blocks and other debris covering much of Europe were initially seen as a consequence of events mentioned in the Bible and other ancient texts. However, with increasing observations there was a growing mismatch between what was expected according to ancient authorities (Godard; Luzzini) and the actual data. This was not necessarily a problem, since influential theologians, such as Augustine of Hippo (AD 354– 430) or the medieval theological scholar Thomas Aquinas (1225–1274), knew that biblical texts needed to be interpreted and that adopting a naive literal reading might do more harm than good to the Christian faith:

In discussing questions of this kind two rules are to be observed, as Augustine teaches. The first is, to hold to the truth of Scripture without wavering. The second is that since Holy Scripture can be explained in a multiplicity of senses, one should adhere to a particular explanation only in such measure as to be ready to abandon it if it be proved with certainty to be false,2 lest Holy Scripture be exposed to the ridicule of unbelievers, and obstacles be placed to their believing (Aquinas 1273, 1st part, question 68). 

Subsequently, attempts to reconcile the growing timescale of geology with biblical chronology became widespread in the eighteenth and nineteenth centuries. The most popular, apart from more metaphorical interpretations of the biblical creation stories, were possibly the ‘gap theory’ (or ‘chaos/ restitution theory’3), claiming an indefinitely long time span between Genesis 1: 1–2 or 2–3 and the ‘day–age theory’ (or concordance theory), which interpreted the days of biblical creation as seven long eras, which might be equated with different geological formations (see Roberts, on Sedgwick).

Genetic Evidence of Geographical Groups among Neanderthals

The Neanderthals are a well-distinguished Middle Pleistocene population which inhabited a vast geographical area extending from Europe to western Asia and the Middle East. Since the 1950s paleoanthropological studies have suggested variability in this group. Different sub-groups have been identified in western Europe, in southern Europe and in the Middle East. On the other hand, since 1997, research has been published in paleogenetics, carried out on 15 mtDNA sequences from 12 Neanderthals. In this paper we used a new methodology derived from different bioinformatic models based on data from genetics, demography and paleoanthropology. The adequacy of each model was measured by comparisons between simulated results (obtained by BayesianSSC software) and those estimated from nucleotide sequences (obtained by DNAsp4 software). The conclusions of this study are consistent with existing paleoanthropological research and show that Neanderthals can be divided into at least three groups: one in western Europe, a second in the Southern area and a third in western Asia. Moreover, it seems from our results that the size of the Neanderthal population was not constant and that some migration occurred among the demes.