The external structure of the mandible is not only under the control of genetic factors, but is also influenced by biomechanical factors such as the masticatory muscles. As is well known, one of the characteristics of the morphology of the mandible which represents the influence of these factors is the gonial angle. It varies from a low angle with strong masseter development to a high angle with reduced muscle activity. The aims of this study were to investigate the internal structures of vertical sections of the mandibular body and to evaluate the relationship between these structures and the gonial angle.
A principal component analysis grouped all cortical thicknesses except for the buccal cortical bone thickness together with large loadings on the ame factor. Buccal cortical bone thickness was more variable than the other variables and showed a different pattern of variation.
The gonial angle was associated with buccal and lingual cortical bone thickness in the second molar section, and was also related to the height of the symphysis and the height and width of the second molar section. These results confirmed the relationship between the gonial angle and the size of the mandibular body at the second molar region.
This study provided evidence that masticatory function influenced on both the internal structure and the size of mandibular body.

View full abstract

The comparative study of the growth of children from very different geographical origins, born in France, shows that different habits of nutritional pattern involve significant differences of Body Mass Index, and pathological risks among some populations. The Maghrebian children intake more saturated fat when their socio-economic status increase, and they present often evident overweight at each age, with diabetic risks. At the time of the introductio of solid food, Vietnamese children intake traditional food and this pattern appears better for the health.

View full abstract

A model for haploid asexual inheritance of social and individual learning is proposed. Animals of one genotype, individual learners (IL), behave optimally for the current environment and, except for a fixed cost due to learning errors, have the optimal fitness in that environment. Animals of the other genotype are social learners (SL) each of whom copies a random individual from the previous generation. However, the phenotype of a social learner depends on whom it copies. If it copies an IL or a correctly behaving SL, it has the “correct” phenogenotype, SLC. Otherwise, its behavior is wrong and we call its phenogenotype SLW.
Different models for the environmental fluctuation produce different dynamics for the frequency of SL animals. An infinite state environment is such that when it changes, it never reverts to an earlier state. If it changes every generation, social learning can never succeed. If, however, a generation in which the environment changes is followed by l-1 generations of environmental stasis and l≥3, some fitness sets do allow the maintenance of social learning. Analogous results are shown for a randomly fluctuating environment, and for cyclic two-state environments.
In a second type of model, each animal can learn individually with probability L. We examine the evolutionary stability properties of this probability in the infinite state environment. When a generation of change is followed by l-1 generations of stasis, fitness parameters can be found that produce an evolutionarily stable nonzero probability of social learning. In all of the models treated, the greater the probability of environmental change, the more difficult it is for social learning to evolve.

View full abstract

Metric and nonmetric cranial characters of human remains of the prehistoric Okhotsk culture (Okhotsk people) were investigated for evidence bearing on their affinities. The cranial morphology of the Okhotsk people shows standard characteristics of the Neolithic or later Northern Mongoloids. The multivariate analyses suggested that the Okhotsk show close affinities not with the Arctic peoples or inland peoples called the ‘Central Asian group’, but with the peoples in the Amur and Sakhalin. We can not positively identify the specific ancestors of the Okhotsk people, however, because few prehistoric human skeletal remains have been recovered in the Amur and Sakhalin areas. Although the craniometric analysis showed a considerable difference between the Ainu and Okhotsk peoples, the nonmetric cranial variations suggested that the Ainu were originally closer to the Okhotsk than to other Northern Mongoloids even before any admixture.

View full abstract