Completing the multidisciplinary analysis, it is time to try the evaluation of the Carbon-14 test. Although without exhaustive technical pretension, it is important to see what would be the situation of a possible radio-carbonic examination of the Compostelan necropolis.
Carbon-14 dating is a radiometric method based on the constant ratio in living organisms between carbon isotopes (C12 and C14). When the organism dies this relationship changes, due to the radioactive instability and decomposition of the C14 with a well-known time velocity, which allows to calculate the time spent since the body’s death from the difference between the ratio C-12 / C-14.
It is considered an absolute physicochemical method of dating, so it is generally believed that the C14 will accurately give us the age of an ancient bone as a thermometer would give us its temperature, and it is seen in this scientific option a safe solution to The Jacobean question. The reality is far from being so simple. For a very specific and well-defined sample it can be, in effect, simple and safe, but the archaeological survey of the remains of Compostelanos is not only the study of some concrete remains, but those of a necropolis of several centuries of evolution. Your complete study would require to be combined with DNA determination. The C14 and DNA tests are different techniques that provide very different data. The independent use of C14 is characteristic of very old, prior, and even ancient human representations on Earth, which are approximations of millions of years, where an error of a few centuries is insignificant. In expert of human remains is especially valid for remains with dates up to 45/50 thousand years. Nowadays there are laboratories that apply the particle accelerator (AMS) spectrometry, obtaining reliable data of up to 80 thousand years, at which time the margins of error are still very wide.
But in archaeological surveys of human remains, especially in ancient and multicultural necropolis, the combination of C14 and DNA becomes necessary. The object of the DNA here is to identify which fragments with the same C14, belong to the same individual, allowing a count. If the formation of the necropolis is several centuries and includes the succession of several cultures, as is the case of the Compostelan necropolis, the combination of C14 and DNA is essential to obtain results that can have a systematizable interpretive value. It would be necessary to apply the two tests to a wide sampling of the fragments of the urn, practically to all, that by having spent more time outside the urn than within she, and suffering displacement, fragmentation, mixing and contamination, it would be necessary to extend the sampling not only to the entire edicule, but also to the subsoil of the cathedral environment.
In these cases the C14 can guide the start and end dates of burials, which can also be estimated reliably by common archaeological criteria (stratigraphy), but the identification of whether or not remains are compatible with those of a specific well-known person of History would have little or no value. Its realization would require the scraping of a small amount of matter in each analyzable fragment, and in the course of twenty centuries it has undergone displacements, fragmentations and mixtures or contaminations, thousands of bone fragments from mixed and superposed tombs, Which would require a very high sampling of double determinations, to detect the chronology, to assess the count and estimate the degree of mixing and general pollution that allows to make rigorous conclusions and that would entail an extraordinary and complex deployment of archaeological re-excavation and Security measures and control of the entire cathedral subsoil. The study, in addition to a halting of temple activity, required such a large amount of resources and a high cost that its funding would only be advisable to address if it provided us with necessary and relevant information, Feasible to achieve, and offer a precise scientific benefit. The indication of such a study could only be based on the need to find out something essential together with a full guarantee of resolution, and neither of the two basic premises are given here. The possibilities of giving a very open chronological interval, several centuries, between the oldest and the least ancient remains of the whole, are so high that would invalidate its intended effectiveness. Confirm a contemporaneous antiquity to the times of Christ, is more a desire than a guarantee achievable by science and, since it is not possible to register identities, the chances that the test would be resolute are meager.
Also the remains may be subjected to scanner, magnetic resonance, computerized axial tomography, ultrasound or bone scintigraphy, tests of very high scientific value, but also have no indication here by the same criterion. It could also be analyzed the necropolis that guard the apostolic remains of San Pedro and San Pablo, or of some Saints whose identity is questioned, and to historical, political, military, emperors, etc., can always find an important historical criterion Which may justify the alleged timing of those determinations.
It is easy to question yesterday’s results with today’s technology, but as much or more questionable is to think that the C14 has the key to the unknown, and there are no guarantees to precisely resolve such selective dating to such an open sample, and the Professionals are those who dismiss the need and resolving ability of this test. There will be those who suggest that the test be done only to the remains that are guarded today in the urn, and only C14, but this is an insufficient criterion for the experts themselves, because the remains have been a century in the ballot box and many Centuries outside it, which demands to study the whole environment with double analytical determination. The possibilities of obtaining ineffective results are so high that the experts consider the study as “not decisive and not determinant”, so they dismiss the technical indication of the same, which they value as “not advisable, and not decisive”, as well as inefficient For its very high costs. Especially the chances of being able to rejet Santiago or Prisciliano by criteria of chronological compatibility would be useless, and with very high probability that it was positive for both.