The aims of the present study were: (1) to supply further knowledge about variations in nonmetric cranial traits in relation to sex, age and laterality and (2) to evaluate biological distance between samples from a recent population. The incidence of 18 nonmetric variants of the cranium were determined in 3 adult samples of 394 skulls of known sex from North Sardinia (Sassari, Alghero and Ozieri); for the Sassari sample (n = 200) age at death was also known. Some significant sex differences were observed. Age did not appear to influence the frequency of the discontinuous traits but did for legibility. Side differences may provide important information about environmental influences. The interpopulation analysis indicates a stronger relationship between samples that are geographically closer (Sassari and Alghero), in accordance with other studies, strengthening the hypothesis of the validity of the use of nonmetric traits in the study of the peopling of a territory.

The purpose of the present study was to analyse the replicability of the scoring of discontinuous traits. This was assessed on a sample of 100 skulls from the Frassetto collection (Dipartimento di Biologia Evoluzionistica Sperimentale of Bologna University) analysed through intraobserver comparisons: the discontinuous traits were determined on the same skulls and by the same observer on 3 separate occasions. The scoring was also assessed through interobserver comparisons: 3 different observers performed an independent survey on the same skulls. The results show that there were no significant differences in the discontinuous trait frequencies between the 3 different scorings by the same observer, but there were sometimes significant differences between different observers. Caution should thus be taken in applying the frequencies of these traits to population research. After an indispensable control of material conditions (subject age included), consideration must be given to standardisation procedures between observers, otherwise this may be an additional source of variability in cranial discontinuous trait scoring.