A metric analysis ofCercopithecus aethiops dentition

Normative adontometric data are presented on a sample of 100 adult Cercopithecus aethiops(51 male, 49 female). When correlation effects among the teeth were held constant through multivariate canonical analyses, contributions of individual tooth loci to the male-female distance were found to be similar to those isolated by univariate means. The present study fails to support Garn’s field theory of sex dimorphism. When these patterns of sexual dimorphism were contrasted with those of three other conspecific groups, the anterior teeth were found to show greater intrapopulation variation than the posterior teeth. This, together with the finding that Penrose’s shape distances between the groups were greater for anterior than postcanine teeth, provides evidence in support of Suolé’s hypothesis. The latter suggests, inter alia, that high coefficients of variation indicate a proportionately higher environmental than hereditary contribution to phenotypic variation. Negative correlations between tooth size and coefficients of variation suggest that tooth-size variability is related to size rather than occlusal complexity.     

Family studies of tooth size factors in the permanent dentition.

Correlations between dimensions of the permanent teeth in Australian Aboriginals were studied by factor analysis to disclose the main sources of shared variability. Findings indicated that in both males and females most of the common variability in the tooth dimensions could be accounted for by factors representing mesiodistal size of anterior teeth, buccolingual size of anterior teeth, generalized size of the premolars and generalized size of the molars. Factor scores derived from the analysis were used to calculate intraclass correlations among brothers and among sisters. These correlations tended to be higher for the factors contributing most to the common variability indicating that the factors might represent fields under direct genetic control. There was no trend for intraclass correlations among siblings derived from multivariate scores to be consistently higher than those based on observed tooth dimensions. The main advantage to the user of factor analysis is the ability to interpret associations between interrelated variables more objectively than is possible by conventional correlation methods.     

猕猴牙齿的变异性研究

本文是猕猴（Ｍａｃａｃａｍｕｌａｔｔａ）７个亚种１３０个头骨的牙齿比较研究结果。在２２项变量中,有１２项表现出明显的性二型,对另外１０项不等于２２项的单因子方差分析表明,除Ｍ＿２近中远侧距离（ＬＭ＿２ＭＤＬ）外,其余变量在７个亚种之间具有显著性差异。判别分析结果说明,其中６项变量虽对亚种的划分具有显著性贡献,但各亚种间的总判别率仅为３２．５６％,亦即牙齿结构在猕猴各亚种间的变异较小。６项变量组成的星状图表明,印度指名亚种与中国各亚种的牙齿形态有较大差异。在中国猕猴各亚种间,指名亚种ｍｕｌａｔｔａ（Ｃｈｉｎａ）与福建亚种ｌｉｔｔｏｒａｌｉｓ和西藏亚种ｖｅｓｔｉｔａ与川西亚种ｌａｓｉｏｔｉｓ表现出较大的相似性。猕猴的牙齿结构随纬度不同呈现出梯度性变化。各亚种间的牙齿差异主要表现在大小或形状方面,这与不同亚种的个体大小相关。     

A factor analysis of morphogenetic fields in the human dentition

The traditional morphogenetic fields of the human dentition were evaluated by means of factor analysis of dental dimensions taken from a series of human crania. When crown length, crown width and crown index were considered separately, factors emerged which could be identified with the tooth group fields. But a combined crown length-crown width analysis generated factors which extended beyond the regional tooth groups. Crown width itself was revealed to be an important axis of morphologic intergration. It was concluded that univariate methods are not adequate for identifying morphogenetic fields; the teeth must be treated as multidimensional units where the correlation among dimensions is accounted for.     

Application of two tests of multivariate discordancy to fisheries data sets

The generalized (Mahalanobis) distance and multivariate kurtosis are two powerful tests of multivariate discordancies (outliers). Unlike the generalized distance test, the multivariate kurtosis test has not been applied as a test of discordancy to fisheries data heretofore. We applied both tests, along with published algorithms for identifying suspected causal variable(s) of discordant observations, to two fisheries data sets from Lake Erie: total length, mass, and age from 1,234 burbot, Lota lota; and 22 combinations of unique subsets of 10 morphometrics taken from 119 yellow perch, Perca flavescens. For the burbot data set, the generalized distance test identified six discordant observations and the multivariate kurtosis test identified 24 discordant observations. In contrast with the multivariate tests, the univariate generalized distance test identified no discordancies when applied separately to each variable. Removing discordancies had a substantial effect on length-versus-mass regression equations. For 500-mm burbot, the percent difference in estimated mass after removing discordancies in our study was greater than the percent difference in masses estimated for burbot of the same length in lakes that differed substantially in productivity. The number of discordant yellow perch detected ranged from 0 to 2 with the multivariate generalized distance test and from 6 to 11 with the multivariate kurtosis test. With the kurtosis test, 108 yellow perch (90.7%) were identified as discordant in zero to two combinations, and five (4.2%) were identified as discordant in either all or 21 of the 22 combinations. The relationship among the variables included in each combination determined which variables were identified as causal. The generalized distance test identified between zero and six discordancies when applied separately to each variable. Removing the discordancies found in at least one-half of the combinations (k = 5) had a marked effect on a principal components analysis. In particular, the percent of the total variation explained by second and third principal components, which explain shape, increased by 52 and 44% respectively when the discordancies were removed. Multivariate applications of the tests have numerous ecological advantages over univariate applications, including improved management of fish stocks and interpretation of multivariate morphometric data.     

Heterochrony and sexual dimorphism in the skull of the Liberian chimpanzee (Pan troglodytes verus)

Allometric methods and theory derived from principles of relative growth provide new and powerful approaches to an understanding of the nature and development of sexual dimorphism among living primates. The Frankfurt collection of Liberian chimpanzee skulls and mandibles provides a large skeletal sample from a single natural population of wild shot animals, including individuals of all ages and both sexes, and allows investigation of allometric and heterochronic patterns of sexual dimorphism. Univariate, bivariate, and multivariate analyses are utilized in this study in order to ascertain the ontogenetic nature of male-female differences in the skull of the Liberian chimpanzee. The results of univariate and multivariate analyses indicate that, while overall levels of sexual dimorphism in the chimpanzee skull are small, the greatest differences are in dimensions of the viscerocranium, while neurocranial dimensions and orbital size tend to be less dimorphic. Bivariate regressions of 21 cranial variables against basicranial length document positive allometry in many facial and mandibular dimensions, and isometry or negative allometry for most neurocranial dimensions. The data confirm previous work in chimpanzees and other anthropoid primates suggesting that males and females are “ontogenetically scaled” in most cranial traits. That is, males and females share the same cranial growth trajectories, although ending up at different points. Both rate and time hypermorphosis are suggested as underlying causes of ontogenetic scaling in the Liberian chimpanzee.     

步氏巨猿牙齿大小上的变异性和南方古猿类食性假说

步氏巨猿牙齿大小上的变异性表明,在柳城巨猿洞局部地区的堆积中可能有少量时代稍晚的巨猿牙齿标本。晚期步氏巨猿与早期的相比,后部齿显著增大而前部齿则无显著差异。从步氏巨猿牙齿在大小上的演化趋势来看,南非南方古猿类中的纤细类与粗壮类之间在齿列比例上的不同不一定意味着其食性上有大的差异,纤细类与粗壮类也未必有“属”这一分类级别上的差异。     

Tissue contributions to sex and race: differences in tooth crown size of deciduous molars.

This study describes size of constituent deciduous tooth crown components (enamel, dentine, and pulp) to address the manner in which males characteristically have larger teeth than females, and the observation that teeth of American blacks are larger than those of American whites. Measurements were collected (n = 333 individuals) from bitewing radiographs using computer-aided image analysis. Tissue thicknesses (enamel, dentine, pulp) were measured at the crown's mesial and distal heights of contour. Deciduous mesiodistal molar crown length is composed of about 1/7 enamel, 1/3 dentine, and 1/2 pulp. Details differ by tooth type, but males typically have significantly larger dentine and pulp dimensions than females; there is no sexual dimorphism in marginal enamel thickness. Males scale isometrically with females for all variables tested here. Blacks significantly exceed whites in size of all tissues, but tissue types scale isometrically with blacks and whites with one exception: enamel thickness is disproportionately thick in blacks. While the absolute difference is small (5.56 mm of enamel in blacks summed over all four deciduous molar tooth types vs. 5.04 mm in whites), the statistical difference is considerable (P < 0.001). Aside from enamel, crown size in blacks is increased proportionately vis-à-vis whites. Principal components analysis confirmed these univariate relationships and emphasizes the statistical independence of crown component thicknesses, which is in keeping with the sequential growth and separate embryonic origins of the tissues contributing to a tooth crown. Results direct attention to the rates of enamel and dentine deposition (of which little is known), since the literature suggests that blacks (with larger crowns and thicker enamel) spend less time in tooth formation than whites.     

Tooth replacement in adult Xenopus laevis (Amphibia: Anura)

To determine the time scale of tooth replacement in adult Xenopus laevis (Daudin), three large females of similar size were kept in aquaria at 25 °C for ten weeks. They were anaesthetized twice weekly with MS 222 and impressions of their upper jaws were taken using thin sheets of dental gold-casting wax. Because the erupted tips of the teeth were small (100 μm), the impressions were enlarged by projection so that the presence or absence of a tooth at each locus in the jaw could be recorded. Each half of each animal's jaw was analysed separately and a statistical analysis of the records yielded results for the duration of the Replacement Cycle and Functional Life of the teeth. The range of the median Replacement Cycle time between specimens was 910–1,010h, that of the Functional Life 580–700 h and that of the Gap Period (the time over which loci were unoccupied by functional teeth) 230–420 h. A tentative time scale for the complete tooth development cycle (from tooth germ initiation to complete resorption) was calculated by extrapolation from the results and ranged from 59.07 to 71.29 days.     

Static intraspecific allometry of the dentition in Otoletnur crassicaudatus

Adult static intraspecific allometry of tooth size was evaluated in a sample of 66 Otolemur crassicaudatus (34 male, 32 female). Tooth areas were calculated from mesiodistal and buccolingual measurements of canines and postcanine teeth of both arcades and were scaled to four viscerocranial measurements: bimaxillary width; maxillo-alveolar length; mandibular length and bigonial width. Individual tooth crown areas were also scaled to total skull length, body length and body weight. From the log-transformed analyses it is concluded that postcanine tooth size was unrelated to body length or weight, and poorly correlated to skull length or jaw size. Although viscerocranial size appears to be independent of body size, these measures are well correlated to skull length. It is shown that the longer the skull, the shorter and narrower the maxilla, and the longer and broader the mandible. Canines are shown to scale negatively allometric to skull length, hence, large animals will have relatively small canines.     

Measurement error: Inter-and Intraobserver Variability. An Empiric Study

The intra- and inter-observer measurement error variability was studied using univariate and multivariate statistical tests. Eleven skeletal variables of four individuals each in four Primate species were measured ten times by three different researchers, using six different tools. An average measurement error of 0.52 mm. was obtained. Univariate statistics showed significant differences among reseachers. A multivariate discriminant analysis could also discriminate them. The measurement error may be either systematic or random, and depends not only on the researcher, but also on the tool used, the variable measured, and on the magnitude of the variable. The technique of Measurement Replication is proposed in order to reduce the measurement error, specially when compairing small samples or when trying to find small average differences between populations. The replication technique also reduces the standard deviation of the population sample.     

The contribution of size and shape variation to patterns of sexual dimorphism of the human femur

The present research was undertaken to determine the relationship between patterns of generalized intrapopulational variation determined from principal components analysis and patterns of sexual dimorphism determined from Student's t and discriminant function analysis. The analysis was based upon 17 measurements of 97 femurs from a Middle Mississippian Amerindian population. The results of the principal components analysis indicated that the 17 original measurements could be represented as four principal component variates. Inspection of component loadings lent support to the contention that the first principal component reflected variation in general size while components two to four reflected variation in femoral shape. Analysis of the relationship between principal component loading and male-female differences reflected in Student's t demonstrated a high (0.97) positive correlation between absolute magnitude of loading in the first principal component and magnitude of Student's t. As a result, discriminant analyses of the femur, utilizing univariate criteria for the inclusion of variables, have been biased in the direction of size variation. Subsequent stepwise discriminant function analyses demonstrated that an adequate discriminant model must reflect all dimensions of morphological variation at the intrapopulational level.     

What best explains vigilance in elk: characteristics of prey, predators, or the environment?

We quantified the vigilance levels of elk (Cervus elaphus) preyedon by wolves (Canis lupus) in Yellowstone National Park, betweenJanuary and May in 2005 and 2006, and used Akaike's informationcriterion to compare a set of 38 regression models for vigilancelevels. These models combined up to 9 predictor variables of3 types: characteristics of the prey group (herd size and composition),characteristics of the predator (wolf pack size, distance away,and the presence/absence of a kill), and characteristics ofthe local environment (distance to woodland edges, snow depth,and snow cover). The set of models spanned a range of complexityfrom simple univariate models to complex combinations with upto 3 variables of each type. Complex models incorporating thecharacteristics of the wolf pack, the structure of the elk herd,and the environmental conditions had higher information contentthan simple models. Although univariate models of vigilancedetect significant relationships, they have low informationcontent relative to multivariate models. These results showthat elk assesses factors of several types when assessing riskand deciding how much time to allocate to vigilance. In particular,we found that all well-supported models of vigilance includedseveral "prey" variables and several "predator" variables. Thisresult highlights the need to consider information about predatorswhen trying to explain variation in vigilance levels in prey.     

Numerical analysis of sexual dimorphism inSaguinus dentition

Among New World monkeys, more or less sexual dimorphism exists in the dentition, especially in the Cebidae. On the other hand, the Callitrichidae includingSaguinus are said to be characterized by a broad lack of sexual dimorphism with the exception of the reproductive organs. In the present article, sexual dimorphism in the dentition of someSaguinus species was reconfirmed using univariate and multivariate analytical methods. The results of the analysis were as follows: (1) there is no sexual dimorphism in the canine tooth size, except for the upper canine ofS. geoffroyi and lower canine ofS. mystax; (2) the overall tooth size difference between males and females is slight or none inS. geoffroyi, S. leucopus, andS. fuscicollis, relatively small inS. oedipus andS. mystax, and rather larger inS. midas; (3) an overall difference in shape factor between both sexes exists in all species ofSaguinus to a greater or lesser extent; (4) although only slight sexual dimorphism is recognized in the canine tooth itself, sexual dimorphism does exist in some adjacent teeth of the canine in a few species; and (5) there are some interspecific differences in the magnitude of the sexual dimorphism of theSaguinus dentition and these differences are more evident in species inhabiting the peripheral regions of the distribution areas of this genus. Taking all the evidence obtained into account, the sexual dimorphism in theSaguinus dentition must be re-investigated in comparison with other genera of the Callitrichidae.     

Tooth cusp sharpness as a dietary correlate in great apes

Mammalian molars have undergone heavy scrutiny to determine correlates between morphology and diet. Here, the relationship between one aspect of occlusal morphology, tooth cusp radius of curvature (RoC), and two broad dietary categories, folivory and frugivory, is analyzed in apes. The author hypothesizes that there is a relationship between tooth cusp RoC and diet, and that folivores have sharper teeth than frugivores, and further test the correlation between tooth cusp RoC and tooth cusp size. Eight measures of tooth cusp RoC (two RoCs per cusp) were taken from 53 M²s from four species and subspecies of frugivorous apes (Pongo pygmaeus, Pan troglodytes troglodytes, Pan troglodytes schweinfurthii, and Gorilla gorilla gorilla) and two subspecies of folivorous apes (Gorilla beringei beringei, and Gorilla beringei graueri). Phylogenetically corrected ANOVAs were run on the full dataset and several subsets of the full dataset, revealing that, when buccolingual RoCs are taken into account, tooth cusp RoCs can successfully differentiate folivores and frugivores. PCAs revealed that folivores consistently had duller teeth than frugivores. In addition, a weak, statistically significant positive correlation exists between tooth cusp size and tooth cusp RoC. The author hypothesizes differences in tooth cusp RoC are correlated with wear rates, where, per vertical unit of wear, duller cusps will have a longer length of exposed enamel ridge than sharper cusps. More data need to be gathered to determine if the correlation between tooth cusp RoC and tooth cusp size holds true when small primates are considered. Am J Phys Anthropol 153:226–235, 2014. © 2013 Wiley Periodicals, Inc.     

中国四种鼯鼠的头骨形态学(英文)

针对长期以来有关鼯鼠分类地位的争议,该研究基于查看、测取60号鼯鼠成体头骨(每号头骨测取26个可量性状)共计1560个数据,运用多变量、单变量分析方法,对鼯鼠属(Petaurista)中的P.yunanensis,P.philippensis,P.hainana以及P.petaurista头骨可测量数据进行了统计学分析,以探讨上述4种鼯鼠的头骨形态差异以及P.yunanensis和P.hainana的分类地位。结果显示:(1)上述可测量头骨性状在该4种鼯鼠中不存在性二型现象;(2)上述4种鼯鼠在所测量的头骨性状上两两间均存在显著差异;(3)P.philippensis与P.hainana之间的头骨形态差异程度远大于P.yunanensis与P.philippensis之间的差异。该结果在宏观统计分析水平上为上述4种鼯鼠的种地位有效性提供了佐证,与前人基于分子水平(mtDNA)的种地位有效性研究结果相似。     

Interspecies difference in placement of developing teeth and its relationship with cross-sectional geometry of the mandibular symphysis in four primate species including modern humans

The form of the anthropoid mandibular symphysis has recently been addressed in association with spatial requirements for the forming anterior teeth. To evaluate potential relationships between the symphyseal shape and teeth further, the growth patterns of the symphyseal region and the positioning of the tooth crypts were examined using CT data, comparing four primate species (modern humans, chimpanzees, Japanese monkeys, and hamadryas baboons) with varied symphyseal curvature and tooth size. First, results showed that interspecies differences in overall mandibular shape including symphyseal inclination and bicanine width are consistently expressed throughout postnatal ontogeny, although local symphyseal configurations related to the superior transverse torus (STT) tended to change considerably during growth in chimpanzees. Second, the four species were found to exhibit differentiated formation positions of the incisor and canine crypts. In particular, I2 developed between I1 and C in humans with a broad bicanine space and small teeth, whereas it was positioned posterior to I1 and above C in the cercopithecines with an extremely narrow bicanine space. In chimpanzees, despite the large bicanine width, I1 and I2 grew with a large antero-posterior overlap owing to their large size. These results indicate that the dental positioning is determined in concert with the size balance of the available mandibular space and forming teeth. Finally, the positions/contours of I2 crypt were shown to correspond strongly with the STT across the taxa. This suggests that interspecies differences in symphyseal shape should be interpreted partially by the species-specific positional relationships of the developing anterior teeth.     

Estimation of sex from the dimensions of foot, footprints, and shoe

This study intends to determine if the sex of an individual can be identified by foot lengths, shoe lengths, and/or footprints. For this purpose, foot length, foot breadth, and foot heel breadth of 506 subjects, comprising 253 females and 253 males ranging from 17.56 to 82.92 years of age, were taken. In addition, the footprints (length, breadth, and heel breadth) and footwear (length and breadth) of the same subjects were measured. Finally, the shoe size of the subjects was recorded. Univariate and multivariate discriminant function models were developed for sex allocations. Statistical analyses indicated that univariate models correctly assign approximately 67-94% of individuals to their correct sex groups. Among univariate models the most reliable measurement was shoe length. The results of multivariate models were better than those of univariate ones, with an approximately 82-96% correct assignment. The best multivariate model was comprised of four variables: foot length, shoe length, shoe breadth and shoe size. It could be suggested that these discriminant functions can provide useful clues to establish personal identity whenever complete or partial feet, footprints, or footwear are recovered.     

Efficacy of cranial versus dental measurements for separating human populations

Cranial and dental measurements were taken on 100 skulls, consisting of 20 specimens each, representing five different human populations. In addition to traditional cranial and dental measurements, sets of nonstandard basicranial and cervical dental measurements were collected. The data were subjected to univariate and multivariate analyses to determine what kinds of data best sort human populations. Both univariate and multivariate analyses indicate that traditional and nontraditional cranial measurements separate major human groups better than do dental measurements, with traditional cranial measurements providing the best sorting criteria. The cervical dental measurements proved to be better sorters of human groups than the traditional maximum dental measurements for univariate, but not for multivariate, analyses. Thus, when utilizing univariate techniques, osteologists can increase sample sizes of teeth by collecting cervical data.     

Allometric analysis of dental variation in a human population

There exists an extensive literature that deals with interspecific allometry, eg, brain size-body size relationships among species. Yet comparatively little attention has been paid to intraspecific or static adult allometry. An intraspecfic allometric analysis was conducted on the complete permanent dentition of a prehistoric American Indian population (N = 156). Mesiodistal and buccolingual measurements were logarithmically transformed and regressed on log transformations of femur length, an estimate of body size. When measurements of antimeric teeth were introduced together into common regressions on femur length, 20 of the 32 slopes were significantly different from zero. Thirty-one of the slopes ranged between zero and one and clustered between 0.2 and 0.4. Hence, negative allometry describes the tooth size-body size association, ie, taller individuals in general possess absolutely but not relatively larger teeth than shorter individuals. In addition, no significant sex differences for the regression slopes were observed. Though significantly correlated, tooth size and body size variables are too weakly associated to permit accurate predictons from regression equations. Evolutionary implications of intraspecfic dental allometry are discussed.