## 3 Results and Discussion
### Climatic Conditions and Mobility
Taking into consideration the consumption of liquids other than water could cause a variation of \(\sim\)15% in oxygen isotopic values [19]; compared to the maximum variation of \(\delta^{18}\)O\({}_{\text{ap}}\), for a population that lived in the same region it could be \(\sim\)1.68% [19]. Therefore, this maximum value of 1.68% cannot fully explain the oxygen isotopic range for Edessa individuals (with oxygen apatite values ranging from \(-\)7.4% to 9.5%), and and so it seems that in the same group there are individuals that seem to be foreign to each other. When the \(\delta^{18}\)O\({}_{\text{ap}}\) values are plotted (Figure 5), 50% of individuals fell within the range of \(-\)7.4% to \(-\)9.5%, with mean values of \(-\)8.3% (s.d. 1.1%). Taking into consideration the maximum variation of oxygen isotopic values of 1.68% (due to different diet between humans and to different recharge altitudes), we can assume that the individuals whose \(\delta^{18}\)O\({}_{\text{ap}}\) values fall in this range (\(-\)7.4% to \(-\)9.5%) consumed water from local sources, while individuals with values outside this range consumed water from nonlocal areas. [PERSON] [19] showed that \(\delta^{18}\)O\({}_{\text{en}}\) is highly correlated with the local \(\delta^{18}\)O\({}_{\text{w}}\) of drinking water in Greece. Using this equation, \(\delta^{18}\)O\({}_{\text{w}}\) = 1.020*\(\delta^{18}\)O\({}_{\text{en}}\) - 32.941, which relates spring water in Greece with the \(\delta^{18}\)O\({}_{\text{en}}\) (Carbonate) (v-SMOW) of tooth enamel apatite of recent humans, the isotopic values of consumed water for Agras and Edessa individuals were calculated (Table 3). In Figure 6 we present the differences in calculated \(\delta^{18}\)O\({}_{\text{w(ap)}}\) for each site, where the horizontal lines indicate the 1.68% acceptable deviation between individuals, whose median distance is the mean oxygen isotopic value for each site. In the same figure, the range of local water is indicated. The calculated \(\delta^{18}\)O\({}_{\text{w(ap)}}\) (v-SMOW) isotopic values of consumed water for Agras humans ranged from \(-\)10.9% to \(-\)9.6%, with a mean value  
Figure 5: The differences in \(\delta^{18}\)O\({}_{\text{ap}}\) isotopic values of bone apatite between individuals in (**a**) Agras and (**b**) Edessa. In (**b**) the blue circles indicate men and the red triangles indicate women. of \(-\)10.2% (s.d = 0.6%); for Roman Edessa, they ranged between \(-\)11.4% and \(-\)9.2% (excluding samples E/T23, E/T27B E/T32, E/T4B, E/T14A, E/T24, E/T25 and E/T29) with a mean value of \(-\)10.1% (s.d = 0.9% %), while Modern Edessa's spring water (shaded area in Figure 6) oxygen isotope values varied from \(-\)9.5% to \(-\)7.0% [19]. Assuming that minimum and maximum \(\delta^{18}\)O\({}_{\text{w(ap)}}\) isotopic values can differ by 1.68% (due to differences in diet and different recharge altitudes), the acceptable range of \(\delta^{18}\)O\({}_{\text{w}}\) in ingested water is between \(-\)9.6% and \(-\)11.2%. The majority of individuals in Edessa had values outside the contemporary spring waters of the area, both men and women. These values are affected by the climatic conditions of the different areas and time periods that the individuals lived. However, the variability in \(\delta^{18}\)O\({}_{\text{w}}\) values is too great to be attributed only to climatic fluctuations. Taking into consideration the fact that the oxygen isotopic composition of waters from lower altitudes is enriched in \(\delta^{18}\)O compared to the waters of higher origin in a drainage basin, two individuals dwelling at different altitudes within that drainage basin present differences in \(\delta^{18}\)O\({}_{\text{ap}}\). This could be the case for the seven women of Edessa who could have consumed water from higher (300-400 m) altitudes than the men or lived in areas with a colder climate.