Presently available research literature includes no less than a score of North American studies pertaining to the time and sequence of eruption of the primary or 'milk teeth. For only about one-sixth of these studies is the medium of original report a dental periodical, the remaining five-sixths are in anthropological, biological, child development, medical (mainly pediatric) and psychological publications. It is a major objective of this paper to bring together these widely scattered reports and make their contents more readily accessible to members of the dental profession. A second major objective of the paper is that of presenting an epitome of research knowledge concerning the age and order of eruption of deciduous teeth in North American children. This, of course, presupposes a systematic and comprehensive integration of the materials from different studies. The two objectives determine the two parts of the paper: The first-colligation-is carried out under the caption Presentation of Research Materials and the second-synthesis-under the caption Generalizations. There are incorporated in both parts the findings from two previously unpublished investigations.
Abstract No Abstract Available. * Supported in part by a research grant, D-217, from the National Institute for Dental Research, of the National Institutes of Health, Public Health Service.
The North American melting pot simmers slowly, so slowly that for many years to come it will contain a number of recognizable morphologic concentrations. These concentrations are described appropriately as smaller composites within the aggregate, i.e., as sizable clusters resulting from differential combinations of such variables as genetic heritage, geographic habitation, and those phases of social heritage which relate to health care, activity regimen, and dietary consumption. Students of child development have given considerable attention to the physical growth of certain subgroups (e.g., North American children of northwvest European descent) and only meager attention to the physical growth of other subgroups (e.g., North American children of Chinese, Indian, and Mexican lineage). This fact has been revealed with particular force in publications that have colligated investigations for special age periods or growth topics (Io, 12, 14, 22, 13, II). The present paper pertains to the body size of that subdivision of the North American child identified as Mexican. Ethnically, a typical Mexican child is a descendant from sixteenth century admixture of southwest European progenitors and American Indian progenitors, with the latter predominating. There are, however, very considerable differences in the amounts of Indian and white blood in the Mexican population (19, p. 3).1 The studies brought together are partly original and partly those of other investigators. They represent groups of Mexican children residing in central and northern Mexico and in the southwestern region of the United States. Among the aspects of body size considered are weight, stature, stem length, arm span, and 4 dimensions each of the head and neck, the trunk, and the extremities. The age period covered begins at birth and extends to 17 years.
It is the purpose of this paper to report an investigation into the growth of the three major components of human stature during the age period from seven to seventeen years. The report includes 1) tables, specific for sex and oneyear age groupings, giving central tendency and variability values for head and neck length, trunk length, and leg length,2 2) graphic comparison of the mean trends for males and females in each of the three dimensions, 3) tabular and graphic presentation of the mean findings for each dimension at successive ages expressed as percentages of mean stature at corresponding ages, and 4) quantitative analysis of the interrelation of the three dimensions using both an approach of mass statistics (correlation coefficients) and an approach of individual statistics (percentile rankings for specific subjects).
SummaryData for this study were seriatim measures of stature on United States youths of North European ancestry. They were gathered between 1925 and 1932 in Massachusetts and between 1950 and 1957 in Iowa. Statistics from size and velocity analyses for each period were obtained and compared. At age 10 years, mean stature of the 1950–1957 youths exceeded that of the 1925–1932 youths by more than 5·0 cm. It was deduced that less than 2·0 cm of this amount arose from a difference in socioeconomic composition of the samples, and upwards of 3·0 cm from secular increase. In both periods, annual velocity means increased between ages 9 years and 12 years for females and between 11 years and 14 years for males. These increases were greater from the velocity data for 1950–1957 than for 1925–1932. No predictive relationship was found between stature at a pre-adolescent age and early occurrence of adolescent peak velocity for stature.
Abstract This article examines a recently reported generalization. Materials from more than a score of investigations are drawn upon. These materials show there is not a substantial research base for the claim that interbreeding in the United States between black people of African ancestry and white people of European ancestry has resulted in increased lower limb height relative to sitting height.
