Ancestral Food Research Articles

Chemical defense and evolution in the Sacoglossa (Mollusca: Gastropoda: Opisthobranchia)

Recent advances in both the systematics and the natural products chemistry of the order Sacoglossa (=Ascoglossa) in the gastropod subclass Opisthobranchia suggest a revised and improved historical account of the evolution of the group. Although the algal genus Caulerpa makes a suitable model for the ancestral food of the order, other siphonaceous algae are consistent with both morphological and chemical data. At an early evolutionary stage terpenoids are sequestered from the food, and used defensively, often with modification. With an evolutionary switch to different kinds of algal food, there is often a shift to other, related defensive chemicals. A switch to new food source sometimes leads to the abandonment of chemical defense, but in other cases there is de-novo synthesis of defensive metabolites. The synthesis of polypropionates, which are used defensively, occurs in some other gastropods, but otherwise is known only in fungi. The systematic distribution of the defensive polypropionates suggests that their defensive use has evolved several times among gastropods. Failure to detect them may mean that synthetic capacity has evolved more than once, or it may mean that they exist at low levels, perhaps having a non-defensive function.

Caries prevalence and caries intensity among 12,344 schoolchildren of French Polynesia

The caries experience of 12,344 schoolchildren between the ages of 4 and 19 years was studied. The methods used were in conformity with the recommendations of a WHO Expert Committee (1962). Caries prevalence was expressed in terms of age-specific averages of children having one or more df and DMF teeth. The caries intensity was estimated in terms of age-specific averages of df and DMF teeth per person examined and in terms of percentages of missing teeth and decayed teeth indicated for extraction. Intergroup comparisons showing consistent differences revealed trends related to sex, ethnic origin and geographic location. In the primary teeth, caries prevalence and intensity were relatively high. Boys were consistently more affected than girls. Longer retention of primary teeth in boys only partly accounted for this. In contrast to the observations relating to permanent teeth, both cariesprevalence and caries-intensity rates in primary teeth showed little differences when tabulated according to island groups. A high incidence of linear hypoplasia of the upper primary anteriors and a subsequent odontoclastic type of caries were noted. Among Chinese children at the age of five, half of their primary teeth were noted as decayed, whereas among Polynesian and European children in the same age group the figures were, respectively, one-third and as low as one-seventh. The age-specific attack rates of the permanent teeth exhibited a reverse sex trend; with advancing age, girls had increasingly higher DMF scores than boys, a phenomenon only partly accounted for by the earlier eruption of permanent teeth in girls. The racial trend in the caries intensity affecting the permanent teeth was also different from that affecting the primary teeth. The rates for Polynesians were closely followed by those for Chinese, whereas the rates for Europeans were remarkably low. The caries intensity affecting permanent teeth (in contrast to that affecting the primary teeth) also showed a distinct geographic trend. It was highest in Papeete, somewhat lower in the rest of the Iles du Vent and still lower in the Iles sous le Vent and Tuamotu. Schoolchildren in the Austral Islands enjoyed a relatively high caries resistance accompanied by moderate mottling. As there was almost no restorative treatment available, a more realistic picture of the caries condition for the Territory was disclosed by considering the percentages of already missing teeth in addition to those indicated for extraction. On the average, Polynesian boys aged fifteen had three teeth missing, the girls six. One-fourth of all decayed teeth needed to be extracted. This high and early tooth mortality was shown to be a consequence of a rampant smooth-surface caries affecting highly deficient tooth structures of “yellow teeth”. The coincident survey of nutrition suggested that the abandonment of ancestral food habits and their replacement by a diet of refined carbohydrates were responsible for this outbreak of rampant decay. Comparison with other studies made among Polynesian populations showed the culmination in Tahiti of a general trend toward an increasing dental deterioriation which has been brought under some control in the case of the Maoris of New Zealand and among Hawaiians. The WHO standard method proved its practicability and reliability under difficult field conditions. Some minor modifications are proposed. This standard technique seems well suited for establishing internationally comparable data and for world records of caries epidemiology for scientific and public health purposes.