Chemical analyses of skeletal and mummy materials
Twelve bone and mummy samples were analysed for Hg (see Table 2). From the femur of St James (KLR-11251/C94) it is obvious that the surface, which exhibits a Hg concentration of no less than 20,870 ng g−1, has been treated with a Hg-containing substance. It is likely that the Hg also penetrated into the trabecular tissue, which showed a concentration of 4460 ng g−1, whereas the cortical tissue by its 42.2 ng g−1 is below what is generally considered the environmental background of ca. 80 ng g−1 [34, 62]. Thus, the cortical femoral tissue has not been contaminated by the Hg treatment. Judging from these numbers, it is not a case of medical treatment [35, 63], but instead of a posthumous Hg-treatment. Possibly some of the Hg is originating from the application of cinnabar containing paint, the traces of which can still be seen on the surface of the bone (Fig. 16).
The three textile fragments from Vaso A, Vaso 1, and Vaso 2 (KLR-11031/C82, KLR-11032/C83, KLR-11033/C84) and the sample of ‘ash’ from Vaso 6 (KLR-11034/C85) have also been analysed for Hg. All four exhibit extremely high concentrations of Hg varying from 11,228 to 68,668 ng g−1, which most likely is a sign of past conservational treatment. This is also the case for a sample of the skin from the upper side of the foot of St Philip (KLR-11029/C80), showing an extremely high Hg concentration of 309,801 ng g−1. The sample of cortical tibia tissue from St Philip (KLR-11036/C90) shows a Hg concentration of 968 ng g−1, which is a factor of ca. ten higher than the environmental threshold of ca. 80 ng g−1. However, it is also within the range of typical cortical tissue concentrations seen in medicated individuals from medieval Europe [35, 62, 63]. Nevertheless, the Hg in this sample could still originate from conservational efforts. It has not been established when the practice of treating certain diseases, most notable leprosy and syphilis, with Hg was initiated.
The present samples have been relics of the Holy Catholic Church for centuries. It is therefore a distinct possibility that several attempts at conservation have taken place during this time. Mercury has been found in corpses and tombs on numerous occasions: San Francesco Caracciolo , Tycho Brahe [65, 66], Agnès Sorel , several 1700′s aristocratic citizens of Moscow [68, 69], Anastasia Romanov , and Ferdinand II of Aragon and King of Naples . It is therefore not surprising that Hg is found in great concentrations in the textiles and on the exterior of the mummy parts in the present study. It is more difficult to assess with certainty when the Hg conservational treatment of the relics from Santi Apostoli took place.
Looking at the other known cases, Agnès Sorel, who died during childbirth in 1450, could have been medicated with Hg-containing medicine . The same applies to aristocratic citizens of Moscow [68, 69] and many other people in medieval and post-medieval Denmark and Germany [35, 62]. Some may actually have been administered lethal doses of Hg, like Anastasia Romanov . Proven cases of posthumous conservational treatment, as in contrast to medical treatment or poisoning while still alive, probably conducted by the undertakers date from 1516 (Ferdinand II of Aragon), 1601 (Tycho Brahe), and 1608 (St Francesco Caracciolo). Although this is not a very certain basis, it is possible that we see indications that the conservational treatment of the relics at Santi Apostoli with Hg took place after ca. 1500.
Other trace elements
The elements Al, Mn, and Fe are normally considered to be diagenetic when their concentrations are higher than certain threshold values. In particular this is observed in the samples of trabecular and surficial bone in the present study (Table 3). Therefore, we considered the cortical tissues the best and the most pristine material suited for inferences of a biogenic signal.
The measurements of the concentrations of the elements Cu, Sr, Ba, and Pb in cortical tissue of the two apostles allow a comparison with other bone analyses. Strontium and Ba can be interpreted as indicators for the diet and therefore possibly also the provenance [72,73,74,75,76,77,78]. In Fig. 17 the Sr and Ba concentrations of St James and St Philip are compared with four independent data sets: skeletons from a cemetery in Horsens (Denmark), a cemetery from Schleswig (Germany), skeletons from a noble family from Montella (AV, Italy) [36,80–82 and references therein], and perhaps most relevant the cemetery site of Qumran (Israel). The latter burials are closer in both age and geographical site to the apostles . The Qumran samples were re-analysed in this work to yield also Ba, Cu, and Pb. However, it should be noted that the bones from Qumran can well have been subjected to diagenesis, as these bones were devoid of collagen and have likely been in an oxidizing environment due to the low burial depth. It is not known how diagenetic changes in the desert environment would have affect the trace element concentrations, if at all.
Lead and Cu have been interpreted as indicators of social class or degree of urbanisation in the European middle age [34, 80,81,82]. High Cu concentrations in bone have been interpreted as indicative for a diet rich in meat, but it can also be obtained from other kinds of food as well [83,84,85,86,87]. High levels of Cu have also been observed in diets rich in cereals and vegetables . However, some consider Cu as ambiguous with respect to dietary composition . As an illustration, Fig. 18 shows a comparison between the data from St James and St Philip and the same four widely different data sets described above.
Summarizing the chemistry of the cortical bones, compared with other European skeletons that of St Philip appear high in Sr and Pb, while similar in Cu and Ba. The very high Sr concentration found in St Philip is extraordinary and must mean that his diet was very special, at least according to European standards, and it is fitting better with the Qumran individuals. Alternatively, it could the results of a diagenetic process. The high Pb concentration in St Philip can be the result of different environmental exposures and is therefore perhaps not so spectacular. The probability that these trace element concentrations are severely affected by diagenesis is reduced by the normal values of the Cu and Ba concentrations.
St James was not exposed to Cu and was quite similar in Pb to many of the European skeletons. His bones appear low in Sr and low Ba concentrations, which—had he been a European—was indicative of a high social class with a meat-rich diet . Again, the low concentration values make it less likely that the bone has been affected by diagenesis.
For KLR-11034/C85 the ‘ash’ from Vaso 6 and KLR-11036/C90 bone fragments from St Philip are observed As-concentrations almost 100 times higher than the rest of the samples. The Pb concentrations are also elevated for these two samples, by a factor of approximately 10 to 50. These two samples have likely been conserved with a compound holding a mixture of Pb and As. It is not possible to ascertain at what time this conservational treatment took place. For the Vaso 6 material, it could be either before or after the incineration if the word ‘ash’ is to be taken literally.
The organic analyses
The embalming material of St Philip (KLR-12288/C18) had a fatty acid profile, dicarboxylic acids, vegetable sterols, which were all characteristic of a vegetable oil (Fig. 9). The analyses also showed the presence of several hydroxy acids associated with the skin fat of the mummy. The GC–MS analyses also showed the presence of traces of erucic acid, which can be associated with rapeseed oil: even if this fatty acid is a specific marker of this type of lipid material, the presence of the mummy hydroxy fatty acids, similar to those characteristic of aged rapeseed oil, does not on itself allow an identification. However, taken together with the FIA-HRMS analyses, the presence of both rapeseed oil and beeswax can be established. The GC–MS analyses also showed the presence of pimaric, dehydroabietic, and abietic acids, associated with pine resin. Finally, the GC–MS analyses also showed the presence of phenol, cinnamic, and vanillin derivatives that can be associated with flowers or wood. So, it seems these mummy parts were that of a decaying body, with pine resin and fragrances, and rapeseed oil, all of which must be characterized as typical for embalming purposes.
The visually disintegrated ‘textile’ sample in Vaso 2 (KLR-11032/C83) showed the presence of beeswax and traces of insecticides. Both beeswax and the insecticides were probably originating from an attempt of conversation, which for the insecticides likely took place in 1956 or thereafter.
The textile in Vaso A KLR-11031/C82 was analysed by Py-GC–MS which showed that the fiber was characterized by the presence of pyrrole derivatives, phenols, and diketopiperazines, a profile consistent with silk.
The blackened surface on the inside of the lower side of the big box consistently showed the presence of carbon black as well as traces of rapeseed oil. It therefore seems quite safe to conclude that there has been a fire inside the small box, where rapeseed oil has been put aflame. Whether the burnt oil is the same as the oil identified in the encrustation has not been ascertained. Why, or at what time, the fire took place cannot be deducted by the present study. It can be speculated that perhaps the incinerated material in Vaso 6 was burned at the time of the fire in the small box, but again there is no way to find this out with certainty from the present investigation.
The sample in Vaso 6—Philip (KLR-11034/C85 ‘ash’) – is somewhat enigmatic. The GC–MS analyses showed the presence of suberin, which is a material normally found in the bark of trees. The ICP-MS analysis showed large quantities of Ca (16.5 wt%), and remarkably high concentration of Sb and Pb (31.7 µg g−1 and 3500 µg g−1 respectively). The results of XRD and µ-XRF analyses showed 20.8 and 24.4 wt% Ca, respectively. The discrepancy between the Ca-determinations is probably due to inhomogeneities in the sample. It is noteworthy that the XRD pattern is devoid of hydroxyapatite, which means that there is no bone dust in the sample. Rather, there are abundant amounts of gypsum and calcite (CaSO4· 2H2O and CaCO3), which can also be seen to be the only major components in the FTIR spectrum (Fig. 13).
It is therefore possible that the sample consisted of ash of decayed wood mixed with calcite and gypsum which was rich in Sb and Pb. The pertinent questions are what the wood were used for, why it had been burned, and what role the calcite/gypsum mixture played. None of these questions are easy to answer. A proper interpretation of the Vaso 6 material is left for future research.
The encrustation from the canal in the big hole
The large amounts of calcium carbonate in the encrustation identifies it without much doubt as a deposit from running water. Embedded in the porous and brittle encrustation was identified rapeseed oil, which was of a chemical composition indicative of an oil from non-modern times. The radiocarbon dating of the extracted oil gave a date of AD 267–539 (2σ). It cannot be inferred either where the oil came from, nor what its purpose was, but it is likely that the oil was part of the relics associated with St James and St Philip right from start when the relics came to Rome.
The dating of the altar and the dating of the bones
A pertinent question is at what date the reliquary was erected. As mentioned above, the present church was built in the third quarter of the 6th Century. However, it is possible that another architectural structure was present at the site prior to the erection of the church.
The bones and mummy parts of the apostles—if these are indeed from the apostles—have for sure been transported from some previous location to the site of the Santi Apostoli. Not necessarily to a preceding church or the one erected in the 6th Century, but possibly to a preceding crypt or building at the site. The ceramic shard has at some point been part of a ceramic vessel. It can have contained the oil identified in the encrustation, which in itself surely was part of the altar construction. The encrustation, however, cannot have been moved from a previous location due to its brittle nature. The ceramic vessel, possibly including the oil, can have been transported from elsewhere and into the site of Santi Apostoli, and when it broke, the oil released could have been absorbed and preserved in the pore spaces of the encrustation.
How does this perception fit with the sequence of dates produced in this study? The bone of St James was radiocarbon dated to AD 214–340 (2σ), the oil embedded in the encrustation was radiocarbon dated to AD 267–539 (2σ), and the shard TL-dated to AD 314–746 (2σ) (Fig. 19).
The most important conclusion of our in-depth investigation of the age of the bone sample is that the relic cannot belong to St James. The radiocarbon dates of both ultrafiltrated collagen and the hydroxyproline fraction are identical. In addition, the stable isotopes measurements yield δ13C = -19.25 ‰ and δ15N = 11.3 ‰ for OxcA-38266. These stable isotope values are indicative of the food source of the individual. The δ15N value is elevated (see e.g. [90, 91].). This may be caused by intake of fish, in which case there could be a reservoir effect making the measured radiocarbon date appear too old. If that was the case, the fish must be of freshwater origin and not marine, considering the δ13C value [92, 93]. However, in arid regions plants and animals can also be elevated in δ15N for other reasons . Therefore, another possibility could be intake of veal or goat, because organisms subject to weaning also show elevated δ15N values . Thus, for a human consuming a significant amount of meat from veal or young desert sheep/goat the δ15N will be enhanced. We consider the intake of freshwater fish less likely than the later mentioned food items, in which case there is no reservoir effect and therefore the radiocarbon dates show the correct age of the bone.
But even if we assume that we have to deal with a freshwater reservoir effect, the 14C date then would show an apparent age; the true age of the individual would be younger. This also excludes the relic from belonging to St. James.
One unexpected number is the δ13C of the hydroxyproline date (OxA-39529) of -30.5 ‰. However, δ13C values of hydroxyproline dated bone samples from the Oxford AMS laboratory have been seen to vary from -21 to -31 ‰ (prof. Tom Higham, personal communication) for a reason that is unclear. It is important to note that the reported stable isotope values were measured by IRMS. In general, the AMS also measures a separate δ13C value, which is used for isotopic fractionation correction of the 14C date. This value is normally not reported. In the case of St James, however, it is important to observe that this AMS δ13C-value confirms the one measured by IRMS. That means the low δ13C value is the true value for the dated compound, and the fractionation correction for the 14C date is therefore correct.
Thus, the preserved relic is not that of St James. With the date of AD 214–340 (2σ) the preserved skeletal remains originate from an individual some 130–260 years younger than St James.
Returning to the sequence of events, the oil in the encrustation dates to AD 267–539 (2σ), which is in accordance with the date of the relic (AD 214–340, 2σ), and the date of the shard (AD 314–746, 2σ). From a statistical point of view, consequently, a hypothesis that all three samples are similar in age is acceptable. In a historical context this is, however, unlikely. When the early church authorities were searching for the corpse of an apostle who lived a couple of hundred years earlier, they would look in ancient burial grounds where bodies of holy men might have been put to rest. Accordingly, the bone of the assumed St James was presumably older than the oil and the shard, which was used for the veneration of the relic once the body was recovered.
The use of relics such as those of the church of Santi Apostoli should be placed in the wider cultural context and in the rise of interest in relics of martyrs and saints. The origins of this activity should be searched for in the increasing practice of saint veneration among Christians and their adoption of the Roman practice of sharing meals with the dead beside the grave as a way of honouring the saints at their tombs . Until the middle of the 4th Century, martyr tombs were important worship places. They were usually located outside the city walls, so that worship places and churches in the city itself were physically separated. The translation of bones starting in the second half of the 4th Century intended to end this undesirable separation. The increasing number of believers may also have played a role, since it implied a necessary expansion of tomb shrines into cemetery churches . The first translation we know of is that of St Babylas in AD 354 , whose remains were transferred from a cemetery in Antioch to Daphne and placed in a church especially built for the purpose by governor Caesar Gallus . Immediately afterwards, translations got popular: the translations of St Timotheus, St Andrew, and St Lukas to Constantinople followed one another in a year’s time .
At the same time, our sources reflect an increasing popularity and circulation of relics from the second part of the 4th Century onwards. Despite the criticism of bishop Athanasius of Alexandria († 373) and Shenoute († 465) at the end of the same century and in the following, relics of martyrs and saints began to be moved into the churches [100, 101]. Throughout the Roman empire, bodies or body parts were exhumated, transferred, and reburied in the apse in close vicinity of the altar. So much so that the authorities felt the need to promulgate edicts imposing penalties on those who contravened them and violated tombs, such as that by Constantius II in AD 340–356  or prohibiting the translation of bodies and the selling of relics such as those of Valentinian II, Theodosius I, and Arcadius (AD 386; Cod. Theod IX.17.7). This is also well attested in the West. Despite prohibitions, after a revelation in a dream bishop Ambrose of Milan (AD 340–397) managed to move Gervasius’ and Protasius’ remains to his own basilica. He placed them under the altar, in a place originally destined for bishop Ambrose himself. Paulinus from Nola recorded that Ambrose conducted two more translations, those of St Nazarius (Vita Sancti Ambrosii 32, in PL 14, 29–50, at col. 40CD) and Vitalis and Agricola, who were moved from Bologna to a new basilica in Florence (Vita Sancti Ambrosii 29, at col. 39C). On the other hand, he also mentioned how (secondary) relics were being distributed at that time through networks of the bishops for the sake of glorifying their churches (Vita Ambrosii 33 at col. 41B).
The relics of SS James and Philip may have originated in a similar context. We do not know who found them and/or brought them to Rome. The fact is, however, that they came to glorify the current church of Santi Apostoli constructed in their honor. The close connection between altar and relics assured a link between the saints and the ritual, in the same way that it used to happen with the veneration of the saints at their graves. The date of the relics agrees with this hypothesis. If we consider the founding of the church by Pope Pelagius in AD 556–561 as a terminus ante quem (see dashed rectangle in Fig. 19), then the bones may at that time have been between 236 and 318 years old (1σ). The radiocarbon date of the rapeseed oil in the encrustation was only 23 to 155 years old (1σ) in AD 556, which, for the lower limit of 23 years, is within the boundaries of the accuracy of the radiocarbon dating method taking all possible uncertainties into consideration. The uncertainty of the TL-date of the ceramic shard is so wide, that it can easily fit the interpretation that the date is simultaneous with the papacy of Pope Pelagius I.