Cranial Metrics Research Articles

Characterization of the craniofacial abnormalities of the homozygous G608G progeria mouse model

IntroductionHutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic condition characterized by premature aging, impacting multiple organ systems, including cardiovascular, musculoskeletal, and integumentary. Significant abnormalities in a transgenic mouse model (homozygous G608G mutation), specifically targeting the development of skull and facial bone indices through high-resolution CT scanning and cephalometric analysis.MethodsKey measurements include bone thickness, skull volume, and cranial suture integrity. Bone volume increased significantly in HGPS mice by 8 months of age compared to wildtype mice.ResultsCortical thickness showed a trend toward increased values in HGPS mice. Cranial metrics revealed distinct differences.DiscussionHGPS mice exhibited smaller internasal width, interzygomatic distance, and palatine length compared to WT mice over time.

A craniometric study of the Medieval sample from Deraheib (Northern Sudan)

The history of North Africa has been always tightly connected to events occurring in Eurasia. Human migra-tions in both directions are well-documented in written sources and archaeological records. To gain a comprehen-sive understanding of historical processes, it is essential to study the remains of individuals who inhabited this region during various time periods. A lack of cranial metric data on the Medieval population of North Africa im-pedes thorough investigation of the population history of the region. This paper presents a craniometric study of the sample from the Southern necropolis at Deraheib. This study contributes to filling the existing void in the un-derstanding of the Medieval population of North Africa. According to written sources, the site was a center of gold mining, known as the city of al-Allaki, dated to the 9th to 15th centuries AD. The city attracted a diverse population seeking economic opportunities. Besides this, Al-Allaki served as an important point on the caravan route which was utilized by merchants and pilgrims traversing the Nubian Desert on their way to Jeddah. The study analyzes cranial metrics of a total of 23 individuals (14 male and 9 female) skulls recovered from the southern necropolis Deraheib sample and employs 55 linear dimensions, following Martin's/Howells craniometric protocol as well as some additional measurements. Statistical analyses were performed using the R language packages and the Multican software. Our results revealed heterogeneity of the sample in male and female parts of the sample at the intra-group level: an observation aligning with existing archaeological and historical evidence. The limited size of the sample warns against any firm conclusions regarding affinities of the Deraheib population. Our intergroup comparison has shown that the cranial sample from the Southern Necropolis of the Deraheib site displays morphological features that are more similar to neighboring Caucasoid populations rather than equatorial groups from East Africa.

STARC OSTEOARCH: An open access resource for recording and sharing human osteoarchaeological data

AbstractThis paper introduces an open access resource for recording and sharing macroscopic data on archaeological human skeletal remains: STARC OSTEOARCH. The resource was developed using a cloud collaboration service, Airtable, and it accommodates data collection on individual skeletons as well as disassociated commingled remains. The attributes covered include key information on demography (sex and age‐at‐death), taphonomy (zonation, anatomical preservation, weathering, fragmentation, and other types of post‐mortem alteration), diet (dental diseases and dental wear), mechanical stress (entheseal changes, osteoarthritis, Schmorl's nodes, and vertebral arthritis), biodistances (cranial metrics and nonmetrics and dental metrics and nonmetrics), and various pathological lesions. References and key descriptions of the categories per attribute have been incorporated in the resource to facilitate raw data sharing, which can be achieved using Airtable's sharing functionality. This initiative aims at promoting standard practices in the field and facilitating data collection and sharing.

Intragroup variation in the Pre-Columbian Cuba population: A perspective from cranial morphology

The paper aims to study intragroup variation inside the two pre-Columbian Cuban populations: the aceramic Archaic and the ceramic Taino groups, based on their cranial morphology. The latter applied artificial cranial deformation to all its members, so the groups are referred to as “non-deformed” and “deformed” samples here. Studies across different disciplines suggest evidence of cultural and biological diversity inside the non-deformed group, while local variations of applying the deforming device can be responsible for shape variation across the deformed group. Cranial metrics and non-metric cranial traits of the 92 crania of Cuban origin were analyzed, although the sample size varied between the analyses due to the incompleteness of the crania. Geometric morphometrics was applied to the deformed crania to study the shape variation across the sample. Three deformed crania from the Dominican Republic were analyzed together with the deformed Cuban sample to test the variability of the practice between the islands. Principal component analysis and the Mantel test did not reveal any geographic differences in the cranial metric traits. No morphological differences associated with the antiquity of materials could be seen either based on the available data. The principal component analysis of the Procrustes coordinates of the cranial vault outline in the lateral norm revealed continuous variability of cranial shapes from the ones with more flattened frontal and occipital bones to the more curved outlines, which is probably explained by individual variation. Non-metric traits variation revealed bilateral asymmetry in the expression of the occipito-mastoidal ossicles among the deformed crania. In conclusion, the study did not support assumptions about morphological diversity inside the studied samples or proved the impossibility of available craniological data to reflect possible intragroup differentiation at the moment.

A re‐evaluation of Kulubnarti: A synthesis of the osteoarchaeological evidence

AbstractThe medieval Nubian cemeteries at Kulubnarti (R and S) have greatly impacted bioarchaeological knowledge. Recent dating of the cemeteries showed they are contemporaries, contrary to prior conclusions that the R cemetery was later in date. Four lines of evidence used to argue for socio‐economic status (SES) differences between the cemeteries in the literature are evaluated: (1 and 2) architecture of houses/churches, (3) age‐at‐death distributions and pathology prevalence, and (4) distribution/frequency of textile types. It is hypothesized that the S cemetery is probably a special use cemetery for subadults and/or there was a monastic presence at the site. First, the original monographs and articles were synthesized to describe the characteristics of Kulubnarti. Second, to verify that genetic differences from social isolation due SES disparities were not operating at Kulubnarti, cranial metrics and nonmetrics from the Kulubnarti cemeteries and other samples from medieval Lower Nubia (Semna South, el‐Hesa) were separately input into Mahalanobis D2 variations, principal coordinates analyses and Procrustes analyses to produce and plot biodistances. Space and time differences were also tested via Mantel tests. Third and fourth, age‐at‐death distributions from the Kulubnarti cemeteries were modelled with a binomial logistic regression, as were textile‐type distributions/frequencies. The literature demonstrates that the cemeteries and the settlements/churches attributed to them did not overlap in time. The biodistance plots show that there are only small differences between the Kulubnarti cemeteries, which are not suggestive of genetic differences due to social isolation from SES disparities. The age‐at‐death logistic regression indicates a more than sixfold increase in the odds of infants being interred in the S cemetery, as compared with adult females, and a nearly threefold increase of other subadults. Further, there were no significant differences in textile‐type distributions/frequencies between the cemeteries. Alternative models explaining who was buried in the S cemetery are better supported than differences in SES.

Prevalence of positional skull deformities in 530 premature infants with a corrected age of up to 6\u2009months: a multicenter study

BackgroundPositional deformities (PD) are common during early infancy. Severe cases may result in facial abnormalities and be associated with delayed neurological development in infants. The earlier the detection of PD, the better the intervention effect and the lower the cost of treatment. Currently, there are many studies on PD in Europe and the United States. However, in China, there is little data on the basic metrics and incidence of PD. Premature infants have a high risk of PD. However, there are few studies on PD in premature infants globally, and none in Asia. This study aimed to investigate PD and its characteristics inpremature infants to help its early detection and intervention and thus improve the quality of life for premature infants.MethodsWe analyzed 530 preterm infants who visited the outpatient departments at Xinqiao Hospital of Army Medical University and Maternal and Child Health Care Hospitals of Wanzhou and Yongchuan Districts in Chongqing from September 1, 2016, to August 31, 2017. The head shape data measured by a simple manual method were recorded. The diagonal difference (DD) between the transcranial diagonals and the cranial index (CI) was calculated. PD and its incidences indifferent gestational ages and corrected age groups were analyzed.ResultsAccording to previously defined international diagnostic criteria, the incidence of plagiocephaly, brachycephaly, and dolichocephaly were 51.1, 85.1, and 3.0% respectively, and those of right and left plagiocephalywere69.4 and 30.6%, respectively. The incidence of PD was highest among infants with a gestational age of < 32 weeks and decreased as the gestational age increased. As the corrected age (CA) increased, the incidence of plagiocephaly and dolichocephaly decreased, and the incidence of brachycephaly increased.ConclusionsPD incidence is high among preterm infants. As gestational age decreased, PD incidence and severity increased. Therefore, healthcare providers should implement early PD detection and intervention to prevent the adverse outcomes. The extremely high incidence of brachycephaly and extremely low incidence of dolichocephaly in this study are likely to be due to the variance of cranial metrics caused by cultural differences. The Chinese standards for infant cranial measurements must be established.

Anatomical Predictors of Transcranial Surgical Access to the Suprasellar Space

Objective The suprasellar space is a common location for intracranial lesions. The position of the optic chiasm (prefixed vs. postfixed) results in variable sizes of operative corridors and is thus important to identify when choosing a surgical approach to this region. In this study, we aim to identify relationships between suprasellar anatomy and external cranial metrics to guide in preoperative planning. Methods T2-weighted magnetic resonance images (MRIs) from 50 patients (25 males and 25 females) were analyzed. Various intracranial and extracranial metrics were measured. Statistical analysis was performed to determine any associations between metrics. Results Interoptic space (IOS) size correlated with interpupillary distance (IPD; a = 7.3, 95% confidence interval [CI] = 4.5-10.0, R 2 = 0.3708, p = 0.0009). IOS size also correlated with fixation of the optic chiasm, for prefixed chiasms ( n = 7), the mean IOS is 205.14 mm 2 , for normal chiasm position ( n = 33) the mean IOS is 216.94 mm 2 and for postfixed chiasms ( n = 10) the mean IOS is 236.20 mm 2 ( p = 0.002). IPD correlates with optic nerve distance (OND; p = 0.1534). Cranial index does not predict OND, IPD, or IOS. Conclusion This study provides insight into relationships between intracranial structures and extracranial metrics. This is the first study to describe a statistically significant correlation between IPD and IOS. Surgical approach can be guided in part by the size of the IOS and its correlates. Particularly small intraoptic space may guide the surgeon away from a subfrontal approach.

Case-Control Study of Cephalometrics in Patients with Moyamoya

To determine whether cranial metrics consistently differed between patients with moyamoya and age-, sex-, and race-matched controls. Patients diagnosed with moyamoya disease by cerebral angiogram were obtained from a prospectively collected database through the Department of Neurosurgery at the University of Kansas Medical Center. Control patients matched by decade of age, sex, and race were collected through a deidentified hospital database by International Classification of Diseases-9 and 10 codes for ischemic stroke to identify patients with computed tomography angiograms. Imaging studies for both groups were analyzed to obtain 6 skull metrics: maximum anterior to posterior distance, maximum biparietal distance, bregma to occiput distance, right carotid canal diameter (CCD), left CCD, and cephalic index. Forty-five patients were identified in each cohort. Measurements of mean anterior to posterior skull diameter, mean biparietal skull diameter, bregma to occiput distances, and calculated cephalic index did not demonstrate a statistically significant difference between patients with moyamoya and control patients. Right carotid canal mean diameter was 4.8 mm for the moyamoya group and 5.4 mm for the control group, with a significant raw mean difference of-0.61 mm (95% confidence interval,-0.95 to-0.27). Left CCD was 4.7 mm for the moyamoya group and 5.5 mm for the control group, resulting in a significant raw mean difference of-0.76 mm (95% confidence interval,-1.09 to-0.43). This study identified 2 skull parameters as statistically different in patients with moyamoya compared with a matched control group of patients with ischemic stroke: right CCD and left CCD.

Normal craniovascular variation in two modern European adult populations.

The vascular networks running into the meningeal layers, between the brain and braincase, leave imprints on the endocranial surface. These traces are visible in osteological specimens and skeletal collections, providing indirect evidence of vascular patterns in those cases in which bone remains are the only source of anatomical information, such as in forensic science, bioarchaeology and paleontology. The main vascular elements are associated with the middle meningeal artery, the venous sinuses of the dura mater, and the emissary veins. Most of these vascular systems have been hypothesized to be involved in endocranial thermal regulation. Although these traits deal with macroanatomical features, much information on their variation is still lacking. In this survey, we analyze a set of craniovascular imprints in two European dry skull samples with different neurocranial proportions: a brachycephalic Czech sample (n=103) and a mesocephalic Italian sample (n=152). We analyzed variation and distribution, correlation with cranial metrics, and sex differences in the dominance of the branches of the middle meningeal artery, the patterns of confluence of the sinuses, and the size of the emissary foramina. The descriptive statistics provide a reference to compare specimens and samples from different case studies. When compared with the Italian skulls, the Czech skulls display a greater dominance of the anterior branch of the middle meningeal artery and more asymmetric right-dominance of the confluence of the venous sinuses. There is no sex difference in the middle meningeal vessels, but males show a greater prevalence of the occipito-marginal draining system. Differences in the middle meningeal vessels or venous sinuses are apparently not influenced by cranial dimensions or proportions. The mastoid foramina are larger in larger and more brachycephalic skulls, which increases the emissary potential flow in the Czech sample and males, when compared with the Italian samples and females, respectively. The number of mastoid foramina increases in wider skulls. This anatomic information is necessary to develop further morphological and functional inferences on the relationships between neurocranial bones and vessels at the genetic, ontogenetic, and phylogenetic levels.

Ancestry estimation of three Mediterranean populations based on cranial metrics

The estimation of ancestry is an essential benchmark for positive identification of heavily decomposed bodies that are recovered in a variety of death and crime scenes. This is especially true when reconstructing the biological profile of the deceased as most methods for sex, age and stature estimation are population-specific. Ancestry estimation methods vary from traditional morphological assessment of cranial features and biometric quantification to computer-aided shape analysis and classification with specialised software. The current paper aims to explore population differences between three neighbouring countries (Greece, Cyprus and Turkey) that have been in constant interaction through conflicts and population movements from the ancient past to the present day, through cranial measurements.The sample consists of 160 dry crania of Greek origin, 137 dry crania of Greek-Cypriot of origin Cyprus and 380 CT scans from Turks individuals. Twelve measurements were taken in both dry and virtual skulls. Data were submitted to principal component analysis and discriminant function analysis. Intra- and inter-observer error as well as the measurement error between virtual and physical measurements were quantified using TEM, rTEM and R.Measurement error was very low in all cases. Classification accuracy for cross-validated data ranged from 74.1 to 97.9%. The highest accuracy was obtained for the Turks sample both in males and females. The results are in accordance with genetic data on the three populations.These results create great confidence in the application of the produced functions in forensic cases requiring ancestry estimation in Cyprus, specifically to unidentified individuals from the 1974 conflict. In addition, these standards can be applied in other forensic situations where ethnicity is an issue but the geographic area of origin is limited to the area encompassing Turkey, Cyprus and Greece.

Cranial Shape and the Modularity of Hybridization in Dingoes and Dogs; Hybridization Does Not Spell the End for Native Morphology

Australia’s native wild dog, the dingo (Canis dingo), is threatened by hybridization with feral or domestic dogs. In this study we provide the first comprehensive three dimensional geometric morphometric evaluation of cranial shape for dingoes, dogs and their hybrids. We introduce a novel framework to assess whether modularity facilitates, or constrains, cranial shape change in hybridization. Our results show that hybrid and pure dingo morphology overlaps greatly, meaning that hybrids cannot be reliably distinguished from dingoes on the basis of cranial metrics. We find that dingo morphology is resistant, with observed hybrids exhibiting morphology closer to the dingo than to the parent group dog. We also find that that hybridization with dog breeds does not push the dingo cranial morphology towards the wolf phenotype. Disparity and integration analyses on the ten recovered modules provided empirical support for modularity facilitating shape change over short evolutionary time scales. However, our results show that this is may not be the case in hybridization events, which were not influenced by module integration or disparity levels. We conclude that although hybridization events may introduce breed dog DNA to the dingo population, the native cranial morphology, and therefore likely the feeding eco-niche, of the dingo population is resistant to change. Our results have implications for conservation and management of dingoes and, more broadly, for the influence of integration patterns over ecological time scales in relation to selection pressure.

Virtual reconstruction of the Neanderthal Amud 1 cranium.

We describe a new computer reconstruction to obtain complete anatomical information of the ecto- and endocranium from the imperfectly preserved skull of the Neanderthal Amud 1. Data were obtained from computed tomography scans of the fossil cranium. Adhesive and plaster were then virtually removed from the original specimen, and the fragments comprising the fossil cranium were separated. These fragments were then mathematically reassembled based on the smoothness of the joints. Both sides of the cranium were reassembled separately, and then aligned based on bilateral symmetry and the distance between the mandibular fossae obtained from the associated mandible. The position of the isolated maxilla was determined based on the position of the mandible that was anatomically articulated to the mandibular fossae. To restore missing basicranial and damaged endocranial regions, the cranium of Forbes' Quarry 1 was warped onto that of La Chapelle-aux-Saints 1, and the resulting composite Neanderthal cranium was then warped onto the reconstructed Amud 1 by an iterative thin-plate spline deformation. Comparison of the computer reconstruction with the original indicated that the newly reconstructed Amud 1 cranium was slightly shorter and wider in the anteroposterior and mediolateral directions, respectively, suggesting that it was relatively more brachycephalic. The endocranial volume was estimated to be 1,736 cm3 , which was quite similar to the original estimated value of 1,740 cm3 . This new computer reconstruction enables not only measurement of new cranial metrics, but also inclusion of the Amud 1 specimen in three-dimensional geometric morphometric analyses that were previously difficult due to its incompleteness. Am J Phys Anthropol 158:185-197, 2015. © 2015 Wiley Periodicals, Inc.

Evidence for Divergence in Populations of Bonobos (Pan paniscus) in the Lomami-Lualaba and Kasai-Sankuru Regions Based on Preliminary Analysis of Craniodental Variation

Historical climatic events and riverine barriers influence the distribution of primates. The River Congo exerts the most significant influence on primate distribution in equatorial Africa, but the extent to which the inner basin of the Congo provided a refuge against Plio-Pleistocene climatic fluctuation is poorly understood. In this study we use cranial and dental morphometrics to examine how riverine barriers affect population patterns in bonobos (Pan paniscus). Bonobos and chimpanzees (Pan troglodytes) are sister species and share the distinction of being the closest evolutionary relatives of humans, yet comparatively little is known about bonobo morphological diversity. We selected 55 adult bonobo crania with well-preserved postcanine dentitions and divided them into regions separated by the rivers Lukenie, Kasai, Lomami, and Lualaba. We found good discrimination among these regions in cranial and dental metrics, but whereas the discriminant functions from cranial metrics were statistically significant, the discriminant functions from dental metrics were not. Mean classification accuracy was 89% for craniometrics, and ranged between 72% and 93% for dental metrics. On average 84–97% of phenetic variation was encountered within regions. Our results mirror molecular studies in suggesting that bonobos are characterized by a long-term stable demographic history allowing strong gene flow between regions and precluding drift and population differentiation. There are some indications that the bonobos from the Lomami-Lualaba and the Kasai-Sankuru regions are divergent, but modest sample sizes do not allow us to be conclusive. We would welcome the opportunity to work with field researchers to augment our sample sizes and reanalyze our data.

&lt;i&gt;Nyctereutes terblanchei&lt;/i&gt;: The raccoon dog that never was

Fossils of the raccoon dog (genus Nyctereutes) are particularly rare in the African Plio-Pleistocene record, whilst the sole living representative, Nyctereutes procyonoides, is found in eastern Asia and parts of Europe. In southern Africa, only one fossil species of raccoon dog has been identified - Nyctereutes terblanchei. N. terblanchei is recognised from a handful of Plio-Pleistocene sites in South Africa: Kromdraai, Kromdraai-Coopers and Sterkfontein in Gauteng, as well as Elandsfontein in the Western Cape Province. The validity of this species identification was questioned on the basis of the rarity of southern African fossils assigned to Nyctereutes, that is, fewer than 10 specimens have been identified as Nyctereutes. This study examined this fossil sample of the raccoon dog from the Gauteng sites and compared dental and cranial metrics of the fossil with samples of modern canids and published data. Morphological traits used to distinguish Nyctereutes, such as the pronounced subangular lobe on the mandible and the relatively large size of the lower molars, were observed to be variable in all samples. Analysis showed that the size of the dentition of the southern African fossil samples was larger than that of living raccoon dogs, but fell well within the range of that of African jackals. These results suggest that fossil Nyctereutes cannot be distinguished from other canid species based on metric data alone, and may only be diagnosable using combinations of non-metric traits of the dentition and skull. However, based on the degree of morphological variability of the traits used to diagnose Nyctereutes, as well as the rarity of this genus in the African fossil record, these fossils are more likely to belong to a species of jackal or fox.

The place of Tam Hang in Southeast Asian human evolution

In February 1934, Jacques Fromaget of the Geological Service of Indochina discovered the Tam Hang rockshelter during prospecting work in Northern Laos. During his excavations, the geologist discovered seventeen anatomically modern human skulls. Ten of these skulls have been recovered in association with six largely-complete skeletons. These fossils, which are dated by 14C to 15.7ka, are used to address issues related to anatomical variation and migration in Southeast Asia during the Late Pleistocene. Excellent preservation of the skeletal material allows for estimation of body size and shape in a sample of young adults. Cranial metrics are also used to assess affiliations between Tam Hang and other Southeast Asian fossil samples in an effort to address questions about population migration. This fossil sample demonstrates that Late Pleistocene human activity may be productively addressed by continued work in the highlands of mainland Southeast Asia.

Reconstructing Body Size in Extinct Crown Cetacea (Neoceti) Using Allometry, Phylogenetic Methods and Tests from the Fossil Record

Living cetaceans exhibit interspecific size rang- ing across several orders of magnitude, and rank among the largest vertebrates ever. Details of how cetaceans evolved different body sizes, however, remain obscure, because they lack basic morphological proxies that have been tradition- ally used in other fossil vertebrates. Here, we reconstruct the body size of extinct crown group cetaceans (Neoceti) using different regression methods on extant skull and length data, in a phylogenetic context. Because most fossil cetaceans are fragmentary, we developed regression equa- tions to predict total length based on cranial metrics that are preserved on most fossil crania. The resultant regression equations are based on a database of skull and length data from most extant lineages of cetaceans (n=45 species; 272 specimens), sampling all living mysticete genera and all major clades of odontocetes. In generating predictive equations, we compared both conventional species data regression and independent contrast regression methods, as well as single trait predictors and a new approach that combines the advantages of a partial least squares (PLS) multivariate regression with independent contrasts. This last approach leverages the predictive power of using multiple correlated proxies. Lastly, we used the rare occurrences of fossil cetaceans with preserved total lengths to test the performance of our predictive equations for reconstructing body size from skull measurements alone. Our results demonstrate that incorporating information about phyloge- netic relationships and multiple cranial measures in PLS scaling studies increases the accuracy of reconstructed body size, most notably by reducing prediction intervals by more than 70%. With this empirical foundation, we highlight the outline of major features in the evolution of body size for Neoceti and future opportunities to use these metrics for paleobiological questions.

Mistaken view of taxonomic validity undermines conservation of an evolutionarily distinct mouse: a response to Ramey et al. (2005)

1 Department of Biology, University of Washington, Seattle, WA, USA 2 Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA 3 Department of Biology, Valdosta State University, Valdosta, GA, USA 4 New Mexico Museum of Natural History, Albuquerque, NM, USA 5 Department of Environmental, Population, and Organismic Biology, University of Colorado, Boulder, CO, USA 6 School of Molecular and Life Sciences, University of Limpopo, Sovenga, South Africa

Craniometric variation in a population of mantled howler monkeys (Alouatta palliata): evidence of size selection in females and growth in dentally mature males.

A large body of work on monkey cranial metrics (involving conclusions about interspecific variation, sexual dimorphism, and ontogeny) depends on the assumptions that growth effectively ceases with dental maturity and that intraspecific variation is negligible. We test these assumptions by examining variation in 39 measurements of 166 dentally mature Alouatta palliata skulls from animals found dead on Barro Colorado Island (BCI), Panama. We also investigate whether this population is under size-based selection, since our found-dead sample reflects the natural mortality in this population. The sample was divided into three age stages by occlusal wear (A-C, least to most wear). Female stage A means are significantly smaller than female stage B means for three cranial measures. Female stage B means are significantly smaller than female stage C means for five cranial measures. Male stage A means are significantly smaller than male stage B means for 21 cranial measures. Multivariate analyses confirm this trend of expansion between adult age stages. The dental metric and suture closure data suggest that the cranial expansion in females is due to size-based selection, while the cranial expansion in males is due to significant growth after dental maturity. Sexual dimorphism ratios are highly variable across different samples of A. palliata, indicating that dimorphism varies between populations of this species. These results provide insight into the selective forces operating on the BCI howlers and challenge the validity of the many studies which pool subspecies and assume growth ceases with maturity.

Comparison of population structure in Ohio's late archaic and late prehistoric periods

Previous studies of population structure among prehistoric groups in the Ohio valley region have shown that hunting-gathering populations exhibited a different structure than horticultural populations. Among both Late Archaic hunter-gatherers and Late Prehistoric horticulturists, covariance structures for cranial metrics were found to be homogenous within the populations, but the Late Archaic subpopulations showed little differentiation while the Late Prehistoric subpopulations exhibited a marked differentiation. Biodistance based on cranial discrete trait frequency showed similar patterns, but in the Late Archaic discrete trait distance was associated significantly with the geographical distance separating populations. The present investigation is an extension of the previous studies increasing the Late Prehistoric sample (n = 8 samples and n = 341 individuals) and using the Harpending-Ward model, modified for use with multivariate quantitative data, to estimate the effects of differential gene flow and the amount of differentiation within populations. Results of the present analyses indicate that differentiation among subpopulations, measured by minimum F(ST), was greater in the Late Prehistoric compared to the Late Archaic period. However, for both periods the minimum F(ST) is comparable to values found for historic native populations of the northeast woodlands. Analysis of differential gene flow in the Late Archaic period indicates that geographically peripheral populations were affected more by external gene flow than more central populations. Late Prehistoric populations exhibit a very complex pattern of differential gene flow. We discuss the latter pattern in terms of proposed culture change in the Late Prehistoric period of Ohio.

Cranial metric and discrete trait variation and biological differentiation in the terminal Late Archaic of Ohio: The Duff site cemetery

Cranial metric and discrete traits were collected from adult individuals of the terminal Late Archaic Duff site cemetery (33 LO 111). Comparisons of cranial metric traits among eight terminal Late Archaic samples including the Duff site sample showed that all samples shared the same generalized variance and by inference the same pattern of shape variation. Some significant size differences were found but these were interpreted as reflecting only minor differences in the underlying polygenic system or differences in environmental interactions. The overall similarity in cranial metrics among the terminal Late Archaic samples strongly suggests that they represent populations that, at least, shared a recent common ancestor. Analysis of discrete trait variation in all the terminal Late Archaic samples showed that the biological distances between samples are associated significantly with the between-sample geographical distances. This association accounts for approximately 25% of the variation in discrete trait frequencies. These results along with the results of the analysis of cranial metrics indicate that all of the terminal Late Archaic samples considered here are related, but geographically nearer samples are more closely related than distant ones.