Developmental Stress in Immature Hominines from Late Pleistocene Eurasia: Evidence from Enamel Hypoplasia

Abstract

The differences between Middle and Upper Palaeolithic cultures from Europe have been likened to the contrast between generalized and complex hunter–gatherers. A test of this model is undertaken by comparing the types, amount, severity and timing of episodes of enamel hypoplasia between the two periods among specimens from western Europe and the circum-Mediterranean area. The earlier sample consists of 59 dentally immature individuals with 128 primary and 154 permanent teeth while the later sample consists of 47 dentally immature individuals with 162 primary and 125 permanent teeth. It was predicted that the Upper Palaeolithic would show more variation in the attributes noted above as a consequence of increased social differentiation. While the prevalence (50% of individuals) and severity of enamel hypoplasia do not differ between the samples, the Upper Palaeolithic component is significantly more variable in the types and timing of enamel defects. Localized hypoplasia of the primary canine is absent from the Middle Palaeolithic but very common among Upper Palaeolithic children. Earlier work has linked this enamel defect to craniofacial osteopenia due to low bioavailability of vitamin A. Linear enamel hypoplasia peaks at age 3·5 years in the Middle Palaeolithic sample but is as common at age 2·0 as 5·0 years in the Upper Palaeolithic sample. The age distribution differs significantly. Peak age at stress, combining all types of enamel hypoplasia, is 3·5 years in the Middle Palaeolithic and 0·5 years in the Upper Palaeolithic. The major contrast between the Middle and Upper Palaeolithic in terms of enamel hypoplasia is the advent of stressful episodes in early infancy in the Upper Palaeolithic. This is attributed to the low bioavailability of vitamin A due to the synergistic effects of malnutrition and infection exacerbated by a net increase in population density among socially competitive family lineages.