## 3 Results and Discussion
### Comparison with Other Regions  
In Table 3 we present the carbon and nitrogen isotopic values of bone human samples from sites in Greece and wider Europe from the same period, and in Figure 3 we compare them with the results from Agras. In Figure 3a we present the mean \(\delta^{13}\)C and \(\delta^{15}\)N isotopic values of the Greek sites, while Figure 3b gives the ones from European sites.  
We performed a \(t\)-test in order to compare our results with the ones from other sites in Northern Greece (Treis Elies, Karitsa and Kladeri) and observed that the Agras samples can be separated into two groups, S1 and S2. The \(t\)-test showed that the S2 group had no significant difference from the Treis Elies, Karitsa and Kladeri sites (for \(\delta\)13C: \(t\) = 0.27, \(p\) = 0.78 and for \(\delta\)15N: \(t\) = 0.29, \(p\) = 0.77), while for the S1 group the difference was insignificant for \(\delta\)13C (\(t\) = 2.24, \(p\) = 0.11) and significant for \(\delta\)15N (\(t\) = 3.97, \(p\) = 0.02). The S2 group's isotopic values (especially the subdivision of it, i.e., S2a) like at the sites Treis Elies, Karitsa and Kladeri, indicates a mainly terrestrial C3 and C4 diet [84] with a freshwater protein contribution, which is indicated by the elevated nitrogen values. The S2b group had lower nitrogen values, indicating a C3 and C4 diet with a lower freshwater fish contribution. Notably, the enriched carbon isotopic values in the North Greece sites reinforced the assumption that millet was introduced to North Greece from Europe [85] and afterwards to the rest of Greece. Additionally, S1 samples had enriched nitrogen values, indicating a larger freshwater fish consumption than at the other sites. For the Makriyalos site, a C3 diet was assumed, with low animal protein consumption, as indicated by the depleted \(\delta\)13C and \(\delta\)15N isotopic values [84] compared to Agras and other Macedonian sites. Additionally, S1 samples have enriched nitrogen values, indicating a larger freshwater fish consumption than the other sites.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  
The sites of Athens, Ayios Dimitrios and Halos were \(\delta^{13}\)C depleted. Specifically, the carbon and nitrogen isotopic values in Ayios Dimitrios and Halos indicate a mainly C3 diet with no C4 contribution, with a significant portion of animal protein [61,82], which is in agreement with the results of sample T6b. Finally, Athens had more negative \(\delta^{13}\)C isotopic values, while its nitrogen was more positive than Agras, indicating a C3 diet with higher animal protein consumption [83] compared to Agras.  
To compare with the other European sites, we performed a \(t\)-test and our samples were separated into two groups (Figure 3b): the first was group S1, which had no significant difference for \(\delta^{13}\)C (\(t=0.50\)\(p=0.64\)) and for \(\delta^{15}\)N (\(t=0.07\), \(p=0.95\)), with the site in Croatia having isotopic values that indicated a mixed C3 and C4 diet [63] and the one in Hungary showing elevated nitrogen values that might be due to the incorporation of freshwater fish or to differences in agricultural techniques [66]. The second group is S2, which differed insignificantly in Croatia and Hungary for \(\delta^{13}\)C (\(t=0.85\)\(p=0.46\)), but for \(\delta^{15}\)N the difference was significant (\(t=3.84\), \(p=0.03\)). However, the results of both groups did not agree with the ones of Slovenia, where the C4 contribution was greater than that of C3 [65] and Poland, where, unlike in Agras, there was no evidence of C4 diet [64]. Moreover, in Spain, C3 in the diet outweighed C4, which is more significant to infants' diet [62]; this was in contrast to Agras, where the C4 contribution was quite evident. The rest of our samples, i.e., T6b and T24-KT, had carbon and nitrogen isotopic values different from the other European sites.