Cranial non-metric traits as indicators of hypostosis or hyperostosis.

Cranial non-metric traits (and particularly those traits which are referable to the opposite conditions of hypostosis or hyperostosis) may represent markers of dynamic responses to general and local perturbation of the morphogenetic pattern. According to this hypothesis, a method is introduced for scoring and analyzing the occurrence of such an “ontogenetic stress” by the evaluation of 20 cranial non-metric traits. The scoring procedure is based on semi-quantitative parameters varying with the variable expression of each trait, in order to set the position of that particular feature in the spectrum provided by the distinction between hypostosis and hyperostosis. This kind of approach allows to apply multivariate statistical analysis, as well as to introduce specific thresholds aimed to the evaluation of the traits in terms of presence/absence. Data may be then examined in the light of the variation ranging from hypostosis to hyperostosis, obtaining a single type of evidence that we call hypostotic score.