Pete E. Lestrel

Method for analyzing complex two-dimensional forms: Elliptical Fourier functions

A generalized procedure, elliptical Fourier analysis, for accurately characterizing the shape of complex morphological forms of the type commonly encountered in the biological sciences, is described. Elliptical Fourier functions are derived as a parametric formulation from conventional Fourier analysis, i.e., as a pair of equations that are functions of a third variable. The use of elliptical Fourier functions circumvents three restrictions that have limited conventional Fourier analysis to certain classes of shapes. These restrictions are (1) equal divisions over the interval or period; (2) dependency on the coordinate system, i.e., conventional Fourier functions are not “coordinate free”; and (3) the presence of shapes with outlines that curve back on themselves, a common occurrence. These three limitations are effectively removed with the utilization of elliptical Fourier functions, facilitating the analysis of a much larger class of two‐dimensional forms.

Hominid cranial capacity versus time: A regression approach

Abstract The application of a linear regression approach to hominid data shows that there is more regularity in hominid cranial capacity over time than has been supposed. Two outcomes of this analysis are: (1) the possibility that the South African Australopithecus africanus sites are older than the presently accepted estimates of perhaps around 2·5 million years and (2) the suggestion that the Ngandong (Solo) cranial material is also considerably older than generally assumed; probably, in excess of approximately 250,000 years B.P.

Hominid Phylogeny and Immunology: A Critical Appraisal

Although there seems to be a regular relation of protein change versus time via an exponential equation of the form ID =ekt, nevertheless, examination of the data indicates that such an exponential fit may be premature. Two other models, ID = kt + b and ID = btk + c represent better fits. Without better data none of the models appears convincing.

AGE AT MENARCHE OF UNIVERSITY STUDENTS IN BANGLADESH: SECULAR TRENDS AND ASSOCIATION WITH ADULT ANTHROPOMETRIC MEASURES AND SOCIO-DEMOGRAPHIC FACTORS

Age at menarche has been shown to be an important indicator for diseases such as breast cancer and ischaemic heart disease. The aim of the present study was to document secular trends in age at menarche and their association with anthropometric measures and socio-demographic factors in university students in Bangladesh. Data were collected from 995 students from Rajshahi University using a stratified sampling technique between July 2004 and May 2005. Trends in age at menarche were examined by linear regression analysis. Multiple regression analysis was used to assess the association of age at menarche with adult anthropometric measures and various socio-demographic factors. The mean and median age of menarche were 13.12+/-1.16 and 13.17 years, respectively, with an increasing tendency among birth-year cohorts from 1979 to 1986. Menarcheal age was negatively associated with BMI (p<0.01), but positively associated with height (p<0.05). Early menarche was especially pronounced among students from urban environments, Muslims and those with better educated mothers. Increasing age at menarche may be explained by improved nutritional status among Bangladeshi populations. Early menarche was associated with residence location at adolescence, religion and mothers education.

Shape changes in the cleft palate maxilla: a longitudinal study.

OBJECTIVE The purpose of this study was to compare the shape of the maxilla in Norma lateralis of cleft lip and palate (CLP) patients with non-CLP controls matched for sex and age. This study utilized elliptical Fourier functions to assess the presence of residual shape changes in the cleft palate maxilla after treatment, compared with controls. DESIGN Longitudinal data (n = 25) were available from the Miami Craniofacial Anomalies Foundation. From these data, two samples were selected: group I (mean age and SD, 5.06 +/- 1.82 years) after lip surgery and the initiation of palate surgery and group II (16.58 +/- 2.42 years) well after the conclusion of surgery. Twenty-two of these patients were matched with controls (5.11 +/- 1.33 and 15.91 +/- 2.25 years, respectively). The maxillary outline as seen on the lateral radiograph was (1) traced, (2) fitted with a series of 48 closely placed points, (3) digitized, and (4) submitted to a specially written routine that computes elliptical Fourier functions (EFFs). These EFFs are close analogs of the bounded maxillary outline as judged by the residual or difference between the observed points and the predicted points generated by the Fourier function. Each maxillary outline was subsequently standardized for size and corrected for positioning in two-dimensional space. RESULTS AND CONCLUSIONS Utilizing a three-way multivariate analysis of variance, statistically significant shape differences were obtained for both young and older groups, as well as between the CLP and controls. No significant gender differences were found. Morphological differences consisted of a posterior repositioning of the nasal crest aspect in the CLP cases. These results suggest that although a clinically satisfactory treatment result was obtained, differences in maxillary shape remain.

Secular trends for takeoff and maximum adolescent growth for eight decades of Japanese cohort data.

The presence of secular trends in the onset or takeoff of the adolescent growth spurt and subsequent adolescent growth of Japanese boys and girls were investigated using data published in “The Statistical Report of the School Health Survey” by the Ministry of Education, Science, Sports and Culture, Japan. An optimum kernel regression method was used to derive the biological parameters of the adolescent growth curve. An increasing trend in height at takeoff (i.e., height at the onset of the adolescent growth spurt) and height at peak height velocity (PHV) among Japanese children was evident during the 8 decades covered in this study. Age at PHV (i.e., the timing of the maximum adolescent growth) for each sex has decreased. Age at takeoff (i.e., the timing of the onset of the adolescent growth spurt) has decreased in boys during this century, but was almost constant in girls at about 7.8 years of age. Moreover, the interval between age at takeoff and age at PHV in girls has gradually decreased over this century. Since the birth year 1915, velocity at takeoff for girls was markedly greater than that for boys, whereas peak height velocity for girls was significantly less than that for boys (P < 0.05). Am. J. Hum. Biol. 12:702–712, 2000.

PHYLETIC DIVERGENCE DATES OF HOMINOID PRIMATES

important stimulus for this specialization has been the lack of adequate or predictable pollinator service. With few exceptions, the reasons for inadequate or unpredictable service have not been demonstrated nor even studied. It has been tacitly assumed that autogamy is associated with a depauperate pollinator fauna, and little consideration has been given to the relationship between pollinator service and the composition of the local flora. One can only speculate on the role which competition has played in promoting autogamy. Nevertheless, the burden of proof lies both with the advocate of pollinator paucity as well as that of competition for pollinators. This is especially true if one considers the temperate floras of the eastern United States or the orchid floras of the tropics where autogamous derivates of self-incompatible species grow in areas sustaining a multitude of self-incompatible zoophilous species and a rich pollinator fauna.

Mandibular shape analysis in fossil hominins: Fourier descriptors in norma lateralis

Biological shape can be defined as the boundary of a form in 2-space (R(2)). An earlier study (Lestrel et al., 2010, HOMO-J. Comp. Hum. Biol.) of the cranial vault found that there were statistically significant differences between each of the three groups: H. erectus, H. heidelbergensis, and H. neanderthalensis compared with H. sapiens. In contrast, there was no statistically significant difference among the first three groups. These results suggest that these three groups may have formed single evolving lineage while H. sapiens represents a separate evolutionary development. The purpose of the current research was to discern if the mandible reflected a similar pattern as the cranial vault data. This study used lateral jpeg images of the mandible. Five fossil samples were used: A. robustus (n=7), H. erectus (n=12), H. heidelbergensis (n=4), H. neanderthalensis (n=22) and H. sapiens (n=61). Each mandible image was pre-processed with Photoshop Elements. Each image was then submitted to a specially written routine that digitized the 84 points along the mandible boundary. Each mandible was fitted with elliptical Fourier functions (EFFs). Procrustes superimposition was imposed to insure minimum shape differences. The mandible results largely mirrored the earlier cranial vault study with one exception. Statistically significant results were obtained for the mandible between the H. erectus and H. neanderthalensis samples in contrast to the earlier cranial vault data. F-tests disclosed that the statistical significance was limited to the anterior symphysis of the mandible. This mosaic pattern may be explained by the reduction in prognathism with the concomitant if rudimentary development of the chin as seen in H. neanderthalensis compared to H. erectus.

Stereometric Description And Analysis Of Skull Growth In P. Cynocephalus Anubis (Olive Baboon)

Biosterometric techniques have demonstrated advantages over traditional craniometric methods in describing and analyzing irregular biological forms and form-changes. This paper demonstrates how data obtained with a simple stereoplotting craniostat can be used to precisely describe growth-related changes observed in a cross-sectional collection of olive baboon (Papio cynocephalus anubis) skulls. Data obtained from this extremely prognathic primate species are analyzed using principles of stereographic projections. Demonstrations are made showing how readily understandable representations of otherwise complex multidimensional shapes and shape changes associated with the skull can be made.