Methodology concerns how we go about obtaining data and using those data to assess our theories. Whether we are considering archaeological evidence such as monumental alignments, or other forms of evidence relevant in archaeoastronomy such as ethnohistoric accounts, written documents, or a combination of these, we need agreed-upon procedures that give us confidence that we can reach the best, most reasonable, most reliable, and most sustainable conclusions on the basis of the evidence available. An accepted methodology is vital in any academic discipline, and it will constantly be under review: people will constantly strive to improve it.
One of the most fundamental methodological necessities is to be fair with the evidence. As a statistician involved in the debates about Alexander Thom's theories concerning the British megaliths once decreed: "Observe all there is and report all you observe." In practice it is seldom feasible to observe all there is, so fair ways of selecting (sampling) data become vital. "Fair selection of data" means doing so in a way that will not bias the eventual conclusion. In other words, it is vital that researchers not just consider and present the evidence that favors a favorite theory while ignoring or hiding the rest by accident or by design. This would occur if, in our enthusiasm to find data that fit a favored theory—for example, that ancient stone rows were aligned upon sunrise or sunset on particular days in the year—we kept searching until we found suitable candidates while ignoring many others that did not fit. Unless this principle is followed, no amount of complex statistical analysis will have any value whatsoever.
Nowhere are the dangers more evident than in popular claims that constructions on the ground, such as temples and pyramids, were laid out in the form of celestial constellations. A famous example is the suggestion that various temples at the ancient site of Angkor in Cambodia were laid out in the formation of the bright stars in the constellation Draco. If there are no firm criteria for selecting the buildings to be considered, then, given the large number of stars in the sky to select from, one can obtain surprisingly good fits totally fortuitously. One BBC television documentary, experimenting with this concept, managed to obtain a remarkably good fit between the layout of selected large buildings in New York City and the stars in Leo.
Each of the various different types of evidence about ancient astronomy presents its own methodological challenges. For instance, impressive light-and-shadow effects, occurring only when the sun or moon reach a particular configuration, are well known. Famous examples include the equinox hiero-phany at the pyramid of Kukulcan at Chichen Itza in Mexico, the sun dagger at Fajada Butte in Chaco Canyon, and the passage tomb at Newgrange in Ireland. Each of these, on the face of it, may have been intentional but might be the result of chance. As the American archaeoastronomer Anthony Aveni once said, "In the American southwest, the search for solar alignments [has been] conducted with a fervent passion not exceeded anywhere in the world. Many a weekend was spent by individuals in hot pursuit of daggers of light entering cracks and openings in caves and buildings—especially light patterns that crept across petroglyphs" (Ruggles 2002, p. 444). We have to devise ways of assessing the likelihood that an effect we observe might actually have been intentional. Where we have only the archaeological evidence to go on, this must inevitably involve some sort of statistical analysis.
In alignment studies there is a similar problem, stemming from the simple fact that every oriented building or structure must point somewhere, and there can be many different reasons for choosing a particular orientation. Often an ancient monument contains not just one obvious axis but many different alignments of buildings, stones, or other structures, and to pick and choose between them on the basis of a favored theory will lead to completely misleading conclusions. There are also many different horizon targets—many potential rising and setting points of celestial bodies that we might deem significant if we find alignments upon them. Added to this is a further problem, that the rising and setting positions of stars change over the centuries, owing to precession, and those of the sun, moon, and planets to a lesser extent, owing to the changing obliquity of the ecliptic. If, as is most often the case, we cannot date a structure at all accurately by archaeological means, then if we simply choose the best fit date, the possibilities are almost endless. If we allowed ourselves the fifteen brightest stars, for instance, and a range of five hundred years, we could fit a suitable star and date for one-third of all oriented structures. Clearly we have to be far more careful and critical.
What, then, can we do to reach a reasonable degree of confidence that any alignment, light-and-shadow phenomenon, or similar association that we spot in the archaeological record was actually intentional and meaningful? One possibility is to look for repeated occurrences. This approach has demonstrated the solar and, in some cases, lunar significance of many local groups of monuments in Britain and Europe, a classic example being the Scottish recumbent stone circles. On the other hand, repeated occurrences can only reveal prevailing practices that were widely and consistently adhered to. Another approach is to seek independent evidence that a particular alignment was deliberate. Archaeological excavations can sometimes reveal this, as has been the case at Balnuaran of Clava, near Inverness, Scotland. Here, it seems that the structural stability of a passage tomb was compromised in order to incorporate the correct astronomical alignment.
A fundamental methodological issue arises from the fact that people's behavior is not governed by unbending principles comparable to the physical laws that govern the universe. Even where the strictest doctrines dictated correct practice regarding, say, the construction of a Neolithic tomb, it is likely that some people "did their own thing." Treating archaeological data too much like data from physics, subjecting it to "scientific" testing, will not explain the actions of individuals in particular places and times, according to particular sets of circumstances. The stone circle at Drombeg in Ireland is a single solstitially oriented stone circle among a group of around fifty. Considering the group as a whole, one would be extremely inclined to put the solstitial alignment of Drombeg down to chance. However, it is certainly possible that the builders of this monument did have reasons for the alignment and that it was, in fact, deliberate. The crucial point is that one cannot use this argument to simply assume that the Drombeg alignment was deliberate; to do so would be to fall into the trap that we identified at the start, namely to choose the data that fits a favored theory (the solstitial alignment at Drombeg) while ignoring the rest (the alignments of the other forty-nine circles). Independent corroborating evidence, such as that obtained at Bal-nuaran of Clava, is needed.
Problems of data selection are not confined to archaeological evidence. Ethnographers may have the problem of distinguishing between informants' accounts that genuinely relate to practices that have been endemic for many generations and more recent inventions or intrusions. The situation is also different where we need to reconcile archaeological with historical and other forms of evidence such as iconography and written inscriptions. Thus a Venus alignment at the so-called Governor's Palace at the Maya city of Ux-mal is a one-off that would not be given credence if we did not have a secure date for the alignment, extensive evidence for the importance of Venus in contemporary Maya culture, and many Venus glyphs on the building itself.
Another problem is that some alignments occur naturally, purely by chance, but may well have been afforded significance in the past. A good example is the Hawaiian island chain, which is quite closely aligned with June solstice sunset and December solstice sunrise. From an indigenous perspective, such alignments, once noticed, can seem very impressive, since they appear to demonstrate the integrity and harmony of the cosmos and the inter-connectedness of land and sky. However, this possibility can present a headache for the modern archaeoastronomer seeking to prove that a particular astronomical meaning was attached to a natural alignment in ancient times, especially in the absence of corroborating evidence from history or ethnography. A great many alignments with plausible astronomical connections may well occur naturally in the landscape, and we have no knowledge as to which ones were actually "observed." Once again, we cannot use our own predilections to prejudge the issue.
In short, it is crucial not to try to fit a favorite theory to some evidence. We must select the data fairly and consider the possible alternative explanations. Unless we do this, we risk misleading not only everyone else but also ourselves. How best, in practice, to assess competing interpretations of the evidence at hand raises a series of questions. There is no simple answer to many of them.We must always keep an open mind and always be open both to new ideas and to new data.
Alignment Studies; Archaeoastronomy; Astronomical Dating; Constellation Maps on the Ground; Field Survey; Orientation; Statistical Analysis; Thom, Alexander (1894-1985).
Angkor; Bush Barrow Gold Lozenge; Clava Cairns; Drombeg; Easter Island; Fajada Butte Sun Dagger; Governor's Palace at Uxmal; Grand Menhir
Brisé; Is Paras; Kukulcan; Na Pali Chant; Newgrange; Polynesian Temple Platforms and Enclosures; Recumbent Stone Circles. Obliquity of the Ecliptic; Precession.
References and further reading
Ruggles, Clive. Astronomy in Prehistoric Britain and Ireland, 159-162. New Haven: Yale University Press, 1999.
-. "The General and the Specific." Archaeoastronomy: The Journal of
Astronomy in Culture 15 (2000), 151-177. Ruggles, Clive, ed., Records in Stone: Papers in Memory of Alexander Thom, 442-472. Cambridge: Cambridge University Press, 2002.
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