Developmental abnormalities of the permanent dentition in prehistoric Ohio Valley Amerindians

The frequencies of developmental abnormalities in size, shape, number of teeth, and enamel formation are presented for a sample of 389 prehistoric Ohio Valley Amerindians from the following cultural complexes: Glacial Kame, Adena, Ohio Hopewell, Cole, Fort Ancient, and Erie (Whittlesey Focus). In addition, the magnitude of fluctuating asymmetry is determined for each tooth and for individuals of these groups. Tests of association indicate complexes with Late Diffuse economic adaptations (Glacial Kame, Adena, Hopewell) exhibit significantly higher frequencies of numerical abnormalities of M₃ and M³ enamel pearls, while Late Focal complexes (Cole, Fort Ancient, Erie) exhibit a higher frequency of severe, general linear enamel hypoplasia. The magnitude of fluctuating asymmetry is, however, generally the same in the Late Diffuse and Late Focal groups. The occurrence of two rare abnormalities with large genetic components, essentially limited to one Hopewell and one Adena mound, raises the possibility that the individuals interred in these mounds are biologically related. Since it is widely held that mound burials represent a status class of the population, it is likely that the Late Diffuse sample is biased in favor of a number of highly select population segments each of which contains biologically related individuals. Accordingly, the lower frequency of severe, general linear enamel hypoplasia in Late Diffuse groups is hypothesized as the result of the more advantageous circumstances expected for high status individuals, and the higher frequencies of numerical abnormalities of M₃ and M³ enamel pearls are hypothesized primarily as the result of mitigated selection on masticatory complex integration, and/or a biased sample. Comparisons with the deciduous dentition show the permanent teeth exhibit higher frequencies of developmental abnormalities. This result is explicable in terms of the more favorable developmental environment of the primary teeth, or a stronger developmental canalization.     

Evolution of dentition in prehistoric Ohio Valley Native Americans III. Metrics of deciduous dentition

Deciduous tooth size in Native Americans of the Ohio Valley area is fairly stable from the terminal Late Archaic (3200 BP) through the Late Prehistoric (350 BP) periods. Some fluctuation in average size did occur during this time. These fluctuations most likely reflect random changes due to gene drift. However, no difference in the pattern of interactions among the sizes of teeth (covariance structures) can be demonstrated during this period. Principal components analysis of the buccolingual and mesiodistal dimensions in the total sample indicate that the major axis of deciduous tooth size in the Ohio Valley population shows an allometric relationship, with the dimensions of the anterior teeth increasing (or decreasing) as the 1.33 power of the dimension of m1(1) and as the 2.0 power of the dimension of m2(2). Comparison of the Ohio Valley samples with other samples from the Eastern Woodlands suggests that geography may have played a minor role in structuring deciduous tooth size variation. For the most part, however, widely separated Eastern Woodlands populations appear to have been evolving independently with respect to deciduous tooth size.     

Evolution of the dentition in prehistoric Ohio Valley Native Americans: II. morphology of the deciduous dentition

In order to evaluate the microevolutionary dynamics of morphological features of the deciduous dentition, I collected data on the variation of 57 features (33 crown and 24 root) from prehistoric Ohio Valley populations. I sampled a total of 370 individuals from 26 populations representing a lineage that inhabited the middle and upper Ohio valley region from approximately 3000 to 350 BP. Evolutionary changes in the frequencies of morphological features of the deciduous teeth in this lineage were limited. Over 80% of the features show no significant differences among the populations. The relatively few features that show consistent differences separate pre- and postmaize agricultural populations. I discuss explanations for this change in terms of selection differences or gene flow. The general pattern of morphological trait expression in the deciduous teeth of this Ohio Valley lineage corresponds to what has been termed the Mongoloid dental complex (sinodonty in the permanent teeth). I suggest additional features that, with further study, may be added to this morphological complex. Am J Phys Anthropol 106:189–205, 1998. © 1998 Wiley-Liss, Inc.     

Size and morphology of the permanent dentition in prehistoric Ohio Valley Amerindians.

Metric and morphological characterizations of the permanent teeth from a total of 155 prehistoric Amerindians are presented. The individuals represent samples from three Ohio Valley burial complexes (considered together as the Late Diffuse group): Glacial Kame, Adena and Ohio Hopewell. Metric data include common measures of central tendency and dispersion. From these measures estimates and analyses of the magnitude of sexual dimorphism and relative variability are presented as well as analyses of the patterns of these estimates. Forty morphological characters are also tabulated. The results indicate a number of provisional hypotheses: the generally larger tooth size of the Late Archaic Indian Knoll when compared to the Late Diffuse groups is consistent with the hypothesis of mitigated selective pressures in more technologically advanced groups; although tooth size is smaller in the Late Diffuse groups, dental morphology is as complex, or more so when compared to the Indian Knoll group. Since morphology and size do not covary exactly the biocultural forces resulting in smaller tooth size do not seem to act as strongly on dental morphology; odontological differences within the Late Diffuse arise primarily between the Glacial Kame-Adena and the Ohio Hopewell. These differences correspond to major biocultural changes in this area; although provisional hypotheses concerning odontological variability are erected, hypotheses concerning evolutionary trends must await the discovery of evolving lineages within these groups; similarities are noted among all compared groups including the pattern and magnitude of sexual dimorphism and relative variability. These parameters may be similar for all eastern Amerindians during this period; finally, the morphology of the deciduous dentition, which generally predicts that of the permanent teeth, is found to be less complex than the permanent teeth. This may be the result of a selective disadvantage for the individuals in the deciduous dentition sample which is reflected in the dentition.     

Dental caries, enamel composition, and subsistence among prehistoric Amerindians of Ohio

Six populations of prehistoric Amerindians from Ohio are sampled to establish the relationship of enamel composition and dental caries experience. The populations used included groups practicing hunting-gathering-fishing and maize horticulture, and they represent at least two major cultural traditions, the Late Archaic/Glacial Kame (1000-500 BC) and the Fort Ancient and Sandusky Bay Traditions (AD) 1200-1600). Characterization of enamel composition is achieved using scanning electron microscopy energy-dispersive X-ray analysis. Thirteen elements present are quantified, and they are analyzed with respect to each population's subsistence base using correspondence analysis. Evaluations of cariogenic and cariostatic effects of elements are made on the basis of caries frequency comparisons among the populations. Results indicate that zinc, copper, iron, nickel, and calcium-phosphorus ratio distinguish populations exhibiting high, moderate, and low caries frequency as well as discriminate hunter-gathers from maize horticulturalists.     

On the development of the deciduous teeth in the common seal (Phoca vitulina)

Information on the development of teeth in seals is rare. In this study, histological details are presented from fetuses and several postnatal stages of the common seal (Phoca vitulina), showing that the deciduous teeth undergo a very rapid, short-term, and somewhat incomplete development. This means that the permanent dentition can and also has to ‚out-pace’ the deciduous dentition, because Phoca vitulina, contrary to fur seals, has a very short suckling period after which there is an abrupt change to normal feeding (crabs, fishes).     

Sequence and age of eruption of deciduous dentition in the baboon (Papio sp)

A detailed eruption sequence and associated age of eruption for deciduous dentition in baboons (Papio sp) are presented in this paper. The sequence was determined by evaluation and comparison of the number and kinds of teeth present in nine age cohorts comprising the study sample of 88 males and 87 females who ranged in age from birth to 763 days. Eruption was assessed visually as present or absent. Several statistical methods used to derive the ages associated with the eruption sequence are described. The basic eruption sequence in the sample population is: i¹ i₁, i₂, i², \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm c}\limits_{\rm -} {\rm,}\mathop {\rm c}\limits^{\rm -} $\end{document} m¹ (m², m₂), M₁, M¹. Both sexes show the same pattern, with the exception of the second deciduous molar, where males show a sequence of m₂, m₂, while females show the opposite. Posterior dentition shows the greatest gender-specific variation in average age of eruption.     

Cervical and crown outline analysis of worn Neanderthal and modern human lower second deciduous molars

Despite the general increase in digital techniques for dental morphometric analyses, only a few methods are available to study worn teeth. Moreover, permanent dentitions are studied much more frequently than deciduous teeth. In this study, we address both issues by providing a taxonomic classification of Neanderthal and modern human (MH) lower second deciduous molars (dm₂s) through the analysis of crown and cervical outlines. Crown and cervical outlines were obtained from a three‐dimensional (3D) digital sample of uniformly oriented dm₂s. Both outlines were centered on the centroid of their area and represented by 16 pseudolandmarks obtained by equiangularly spaced radial vectors out of the centroid. We removed size information from the oriented and centered outlines with a uniform scaling of the pseudolandmark configurations to unit Centroid Size. Group shape variation was evaluated separately for the dm₂ crown and cervical outlines through a shape–space principal component (PC) analysis. Finally, quadratic discriminant analysis of a subset of PCs was used to classify the specimens. Our results demonstrate that both outlines successfully separate the two groups. Neanderthals showed a buccodistal expansion and convex lingual outline shape, whilst MHs have buccodistal reduction and straight lingual outline shape. Therefore, we confirmed that the cervical outline represents an effective parameter for distinguishing between the two taxa when dealing with worn or damaged dm₂s. Am J Phys Anthropol 2012. © 2012 Wiley Periodicals, Inc.     

Dental morphology and odontometry of the Tibetan immigrants

Dental features such as size, shape, cusp number and groove pattern, deflecting wrinkle, protostylid, form and size of dental arch and occlusion pattern, as well as crown diameters of maxillary and mandibular dentition of the Tibetan immigrants in India are described. Sex differences in various measurements are also noted. Overall reduction in size, presence of hypodontia of the third molar, and absence of Carabelli's trait are a distinct progressive/evolutionary trend in the Tibetan dentition, while presence of a shovel-shaped lingual surface of central and lateral incisors is a retrogressive/primitive condition. In some of the dental features Tibetans resemble Caucasoid and modern populations, in certain others they resemble other Mongoloid populations, and in still other features they resemble aboriginal populations and fossil hominids.     

Aggregation,interregional interaction,and postmarital residence patterning: A study of biological variation in the late prehistoric middle Ohio Valley

This study examines a perennial problem in anthropology, changes in postmarital residence patterning. Cross‐cultural patterns related to shifts from patrilocal to matrilocal patterns have been attributed to changes in subsistence and/or the result of migrants entering a populated region. Shifts from matrilocal to multilocal patterns have been found to be related to depopulation. This study examines these possibilities in an archeological context through morphometric analyses of human dentition. Comparisons in variability among males and females are made at four Fort Ancient sites in the Middle Ohio Valley that date to sequential time periods between circa A.D. 1000 and 1650. Results show that the earliest site (Turpin) that was occupied during the transition to maize agriculture was patrilocal, whereas two subsequent sites (Anderson and SunWatch) that were occupied after the transition to a maize‐focused diet reflect a matrilocal pattern. The most recently occupied site (Madisonville), occupied during a time of depopulation of the region after a decline in levels of maize consumption and a marked population shuffling contains a multilocal pattern. These results fit well with the various cross‐cultural findings regarding shifts in postmarital residence patterns. Am J Phys Anthropol 154:270–278, 2014. © 2014 Wiley Periodicals, Inc.     

Transplantation of stem cells from human exfoliated deciduous teeth for bone regeneration in the dog mandibular defect

AIM: To investigate the effect of stem cells from human exfoliated deciduous teeth(SHED) transplanted for bone regeneration in the dog mandibular defect.METHODS: In this prospective comparative study, SHEDs had been isolated 5 years ago from human exfoliated deciduous teeth. The undifferentiated stem cells were seeded into mandibular bone through-andthrough defects of 4 dogs. Similar defects in control group were filled with cell-free collagen scaffold. After 12 wk, biopsies were taken and morphometric analysis was performed. The percentage of new bone formation and foreign body reaction were measured in each case. The data were subject to statistical analysis using the Mann-Whitney U and Kruskalwalis statistical tests. Differences at P 0.05 was considered as significant level.RESULTS: There were no significant differences between control and SHED-seeded groups in connective tissue(P = 0.248), woven bone(P = 0.248) and compact bone(P = 0.082). There were not any side effects in transplanted SHED group such as teratoma or malignancy and abnormalities in this period.CONCLUSION: SHEDs which had been isolated and characterized 5 years ago and stored with cryopreservation banking were capable of proliferation and osteogenesis after 5 years, and no immune response was observed after three months of seeded SHEDs.     

浙江天台山落叶阔叶林特征研究

天台山次生落叶阔叶林植物种类丰富 ,科属组成分散。区系成分复杂 ,从属的地理成分来看 ,温带、亚热带分布的类型居多。群落的生活型高位芽植物最多 ,地面芽植物次之。该群落叶的性质以小型叶、单叶、草质、非全缘为主。群落各样地间的相似系数除沟谷 3样地有较高的相似性外 ,其余各样地的相似系数均较低。群落物种多样性指数较高 ,各样地间多样性指数测值变幅较大。群落垂直结构复杂 ,地上成层明显。样地内多数优势种群的年龄结构为衰退型 ,群落的种类组成不稳定。乔木层中多数优势种群的分布格局呈随机分布或均匀分布 ,部分呈集群分布。     

The dentition of the Indian Knoll skeletal population: odontometrics and cusp number.

Data on the permanent dentition of 153 individuals from the well known Indian Knoll skeletal population are presented. Mesiodistal and buccolingual measurements were taken with a Helios dial caliper. Cusp number of maxillary and mandibular molars are recorded. The Indian Knoll dentition is larger than many modern groups but smaller than Australoid or Mesolithic groups. With the exception of maxillary 12, males have larger teeth than females in both dimensions. The lower canine is the most dimorphic tooth. Through rank order correlation, an association was shown between the sexual dimorphism of the mesiodistal and buccolingual dimensions. Compared to modern groups, the Indian Knoll population displays a moderate degree of sexual dimorphism in tooth size. In general, the coefficients of variation were greater for the more distal teeth within morphological classes. Amounts of size variability did not differ significantly between the sexes; moreover, rank order correlations indicated that patterns of variability in both dimensions were similar for males and females. The predominant cusp number pattern for upper molars is 4-3-3 and for lowers 5-5(4)-5. No sex differences were shown for cusp occurrence or bilateral asymmetry in cusp number.     

The deciduous dentition and dental replacement in the Eocene bat Palaeochiropteryx tupaiodon from Messel: The primitive condition and beginning of specialization of milk teeth among Chiroptera

The deciduous dentition and tooth replacement pattern of Palaeochiropteryx tupaiodon from the early Middle Eocene of Messel, near Frankfurt, Germany, are described. Ontogenetic states include fetuses to subadults. The posterior portion of the deciduous dentition (dP3-4) still shows the primitive eutherian condition of molarization, while the anterior part (dI-dC) was already engaged in the evolution of the highly derived condition found in living bats for clinging to the mother's fur. A styliform and sharp anterior dentition is considered a prerequisite in earliest chiropteran evolution. The greatly modified milk teeth of all living bats developed in different clades by parallel evolution under high selective pressure. The tiny and, at initial stages, poorly calcified teeth are substantiated by a newly developed microradiographic technique which is described in detail.     

Early development and replacement of the stickleback dentition

Teeth have long served as a model system to study basic questions about vertebrate organogenesis, morphogenesis, and evolution. In nonmammalian vertebrates, teeth typically regenerate throughout adult life. Fish have evolved a tremendous diversity in dental patterning in both their oral and pharyngeal dentitions, offering numerous opportunities to study how morphology develops, regenerates, and evolves in different lineages. Threespine stickleback fish (Gasterosteus aculeatus) have emerged as a new system to study how morphology evolves, and provide a particularly powerful system to study the development and evolution of dental morphology. Here, we describe the oral and pharyngeal dentitions of stickleback fish, providing additional morphological, histological, and molecular evidence for homology of oral and pharyngeal teeth. Focusing on the ventral pharyngeal dentition in a dense developmental time course of lab‐reared fish, we describe the temporal and spatial consensus sequence of early tooth formation. Early in development, this sequence is highly stereotypical and consists of seventeen primary teeth forming the early tooth field, followed by the first tooth replacement event. Comparing this detailed morphological and ontogenetic sequence to that described in other fish reveals that major changes to how dental morphology arises and regenerates have evolved across different fish lineages. J. Morphol. 277:1072–1083, 2016. © 2016 Wiley Periodicals, Inc.     

A general method for the high-yield isolation of mesophyll protoplasts from deciduous tree species

High yields (1.2–8.0 × 10⁶ g fresh wt.^?1) of viable leaf mesophyll protoplasts have been isolated from a range of mature deciduous woody-plant species (Betula pendula, Alnus glutinosa, Salix caprea var. Kuroyanagi, S. alba var. Tristis, Populus Tacatricho (= P. tacamahacca × trichocarpa 32), Ulmus glabra var. camperdown), and juvenile glasshouse-grown material (B. pendula, B. pubescens, A. glutinosa). Protoplasts are only released if chopped leaf tissue is thoroughly washed prior to digestive enzyme addition. The nature of the washing requirement has been investigated and it has been demonstrated that water soluble compounds are released from chopped leaves which modify their cell-wall structure rendering them resistant to enzymic digestion. When analyzed by paper chromatography the leachate from B. pendula leaves was found to contain the hydroxycinnamic acids p-coumaric acid (PCA) and o-coumaric acid (OCA). Pre-incubation of B. pendula tissue (which is normally susceptible to enzymic digestion) in authentic samples of PCA and OCA prior to enzymic incubation, completely suppressed protoplast yields. The relevance of hydroxycinnamic acids to protoplast isolation and plant tissue culture is discussed.     

Developmental origins and homologies of the hyracoid dentition

Understanding the origins of morphological specializations in mammals is a key goal in evolutionary biology. It can be accomplished by studying dental homology, which is at the core of most evolutionary and developmental studies. Here, we focused on the evolution and development of the specialized dentition of hyraxes for which dental homologies have long been debated, and could have implications on early placental evolution. Specifically, we analysed dental mineralization sequences of the three living genera of hyraxes and 17 fossil species using X‐ray computed microtomography. Our results point out the labile position of vestigial upper teeth on jaw bones in extant species, associated with the frequently unusual premolar shape of deciduous canines over 50 Ma of hyracoid evolution. We proposed two evolutionary and developmental hypotheses to explain these original hyracoid dental characteristics. (a) The presence of a vestigial teeth on the maxilla in front of a complex deciduous canine could be interpreted as extra‐teeth reminiscent of early placental evolution or sirenians, an order phylogenetically close to hyracoids and showing five premolars. (b) These vestigial teeth could also correspond to third incisors with a position unusually shifted on the maxilla, which could be explained by the dual developmental origin of these most posterior incisors and their degenerated condition. This integrative study allows discussion on the current evolutionary and developmental paradigms associated with the mammalian dentition. It also highlights the importance of nonmodel species to understand dental homologies.     

北京山区落叶阔叶林中核桃楸在生长中期的树干液流研究

北京山区落叶叶林优势种－－核桃楸在生长中期没有水分亏缺的条件下,树干的液流速率在很大程度上为微气候因子所决定,特别是大气相对湿度、温度和太阳辐射强度等。核桃楸树干液流速率的日进程和大气相对湿度、温度的日进程具有很好的生态学同步性。在一天中树干液流速率会出现数次波动,有多个峰值,最高峰一般出现在１５：００左右,可达到１６００ｇ／ｈ。在夜晚时核桃楸树干液流速率非常低,一般在５０ｇ／ｈ以下,但总是存在,