Changes in skull components of the squirrel monkey evoked by growth and nutrition: an experimental study

Twenty weanling 6-month-old male squirrel monkeys were allotted to the following treatments: 1) first control animals were killed at weaning; 2) second control animals were killed when 24 months old; and 3) malnourished animals were fed on a low-protein diet and killed at age 24 months. Lateral and vertical teleradiographies were taken. Growth of the neurocranial and splanchnocranial components were measured by volumetric (size estimators) and morphometric (shape estimators) indices. All facial components grew. The neurocranial components showed a heterogeneous behavior: The anteroneural component remained stable, and the increase of the midneural component was compensated by a decrease in the posteroneural component. Malnutrition affected the growths of 1) the craniofacial complex, 2) the splanchnocranium, and 3) the respiratory and midneural components. Growth influenced skull shape through 1) increases of the splanchnocranium and the midneural component relative to the neurocranium; 2) decreases of the masticatory and optic components relative to the splanchnocranium, and 3) decreases of the anteroneural and posteroneural components relative to the neurocranium. Malnutrition influenced skull shape through the relationship between the anteroneural component and the neurocranium. These results confirmed the existence of functional interrelationships among the cranial components. A new approach to craniological studies is suggested.     

Craniofacial morphology in the Argentine Center-West: consequences of the transition to food production

The Argentine Center-West was the southernmost portion of the Andes where domestication of plants and animals evolved. Populations located in the southern portion of this area displayed a hunter-gatherer subsistence economy up to historical times, and coexisted with farmers located to the north. Archaeological and biological evidence suggests that the transition to food production was associated with the consumption of a softer diet and a more sedentary way of life. This study tests the hypothesis that diet-related factors influenced morphological differentiation, by comparing functional cranial components of farmers and hunter-gatherers. Three-dimensional changes on eight minor functional components (anteroneural, midneural, posteroneural, otic, optic, respiratory, masticatory, and alveolar) were measured on skulls derived from both subareas. Volumetric and morphometric indices were calculated to estimate the absolute and relative size of components, respectively. Results of a paired t-test indicated that farmers have a smaller craniofacial size than hunter-gatherers. The components that varied the most were masticatory and posteroneural, showing smaller absolute and relative sizes in farmers. Discriminant analyses indicated that lengths and widths were the most affected dimensions of these and other components. The pattern of differentiation, which involves specific components, enabled us to exclude differential gene flow and stochastic mechanisms as the main causes. Instead, results support the hypothesis that diet-related factors associated with both subsistence economies influenced craniofacial morphology. A proportion of the observed variation associated with size differences can be explained by two systemic factors: the lesser quality of nutrition due to a low protein content in the diet, and a decrease of growth hormone circulation induced by a lower mobility due to sedentism. However, differentiation is better explained by a localized factor: the reduction in the masticatory and posteroneural components in farmers resulted from a decrease of masticatory stresses and workload on the head and neck, linked to the consumption of a softer diet.     

Palatal thickening and facial form in Paranthropus: Examination of alternative developmental models

Paranthropus is distinctive among hominoids in its possession of a greatly thickened hard palate. Although traditionally considered a structural adaptation to counter high-magnitude masticatory stress, alternative developmental models are equally viable. Three models of palatal thickening were evaluated in this study. A mechanical model interprets palatal thickening as a compensatory response to increased instability of the midpalatal suture effected by an anterior placement of the masseteric muscle mass. This model predicts that palatal thickness is correlated with the length of the palate posterior to the masseteric tubercle. Two non-mechanical models consider the thickness of the hard palate to be structurally related to and therefore correlated with either 1) the degree to which the premaxilla overlaps the hard palate in the subnasal region or 2) the height of the posterior facial skeleton. The correlation of craniofacial variables was assessed intraspecifically in ontogenetic series of great ape and human crania. Tests of correlation were performed for each comparison using both residuals calculated from reduced major axis regression of the variable of interest against a measure of cranial size and shape ratios. A significant correlation of palatal thickness with posterior facial height in Pan suggests that the unusually thick hard palate of Paranthropus is directly related to the increased posterior facial height characteristic of this taxon. Further evaluation suggests that extreme palatal thickening in these specimens occurred by virtue of their possession of a nasal septum morphology in which the vomer extends onto the superior nasal surface of the premaxilla. Such a morphology would have constrained the palatal nasal lamina to maintain the approximate level of the premaxillary nasal lamina throughout the growth process thereby promoting palatal thickening. Am J Phys Anthropol 103:375–392, 1997. © 1997 Wiley-Liss, Inc.     

The effects of race,sex, and nutrition on craniofacial differentiation in rats. A multivariate analysis

Wistar and Holtzman rats were fed (a) control diet ad libitum (controls); (b) restricted control diet (undernourished); and (c) low-protein diet ad libitum (malnourished), from weaning to 70 days of age. Mahalanobis D² distances between cranial groups were assessed. Besides, differences among traits were assessed by the analysis of variance and Tukey test. The relative influence of each factor yielded a decreasing sequence: protein-calorie malnutrition (PCM)-Protein deficit (PD)-race-sex. However, this sequence differed between races. The significant sexual dimorphism in Wistar controls disappeared because of PCM and PD. Race and sex, race and nutrition, and race, sex, and nutrition interacted. Traits were classified into: (a) specific, (b) nonspecific, and (c) invariable. The specific race traits were alveolar length and foraminal width. The specific nutritional traits were neurocranial and splanchnocranial lengths and heights, alveolar and neurocranial widths, and the neuro-splanchnorcranial index (NSI) and the neurocranial vertico-transversal index (NVTI). There were no specific sexual traits. It was concluded that nutritional factors can modify a taxonomic distance in three different ways: (a) evoking morphological differences among populations of the same racial group, (b) altering differences among racial groups, and (c) modifying the pattern of sexual dimorphism of a population. It is suggested that craniological studies should take into account only the set of specific traits, disregarding both specific traits due to other factors and nonspecific ones.     

An ectocranial lesion on the Middle Pleistocene human cranium from Hulu Cave, Nanjing, China

The earlier Middle Pleistocene human partial cranium from Hulu Cave, Tangshan, Nanjing (Hulu 1) exhibits an ectocranial lesion which covers most of the anterior neurocranium, largely between the temporal lines and extending from the supratoral sulcus to the anterior parietal bone. The endocranial surfaces and the remainder of the cranium (upper facial skeleton, lateral frontal bone, posterior parietal bones, and mid-occipital bone) are normal. The healed lesion exhibits both resorption and the laying down of new bone. Differential diagnosis suggests that the lesion was caused by either trauma (broad compressive trauma, tensile trauma to the scalp, or partial scalp removal) or burning (with damage to scalp and superficial neurocranium). Dietary deficiencies, infection, and neoplastic disorders do not fit the lesion characteristics. The Hulu 1 specimen therefore joins a growing sample of Pleistocene Homo remains with nonfatal and nontrivial disorders.     

The effect of duration and time of food availability on the photoperiodic response in the male house sparrow, Passer domesticus

We investigated the effects of food availability on the seasonal testicular growth in the photoperiodic house sparrow (Passer domesticus). Two experiments were performed, each lasting 4 weeks. In experiment 1, sparrows were exposed to natural (NDL; group 1), short (8L:16D; group 2) and long (16L:8D; groups 3-5) day lengths with access to food ad libitum (groups 1-3) or for 10 h (zeitgeber time (zt) 0-10, group 4; zt 0 is the time of light onset) or for 8 h (zt 8-16, group 5). Testes recrudesced under long, but not short and natural, day lengths, and the recrudescence under long days was influenced by the duration of food availability. In experiment 2, the sparrows were exposed to short (8L:16D, group 1) and long (16L:8D, groups 2-5) day lengths with access to food ad libitum (for groups 1 and 2) or for 6 h (for groups 3-5) at different times during the 16 h light period (group 3- zt 0-6, group 4- zt 5-11, group 5- zt 10-16). As the expected, the testes recrudesced only under long lengths, but the photoinduction was variable among the 4 groups. The testes grew to full size in groups 2 and 3 that received food either ad libitum or for 6 h at zt 0-6, but to sub-maximal size in the groups that received 6 h food either at zt 5-11 (group 4) or at zt 10-16 (group 5). Altogether, these results support the idea that the photoperiodic regulation of reproduction in a seasonally breeding species is influenced both by the duration and the time of food availability.     

The Neurocranium of the Stereospondyl Mastodonsaurus Giganteus

New and rich material of the stereospondyl amphibian Mastodonsaurus giganteus from Kupferzell in southern Germany allows for the first time a detailed study of the neurocranium of this species. Both sections and uncrushed specimens preserved in three dimensions were examined. The sphenethmoid ranges from the sella turcica region far to the anterior almost towards the nasal capsules, which remained unossified. The basisphenoid persisted as cartilage, whose morphology can be traced from imprints in surrounding bones. The otic is a single but complex element which underwent major ontogenetic changes. During development, the posterior braincase became increasingly ossified and finally formed a single, compound unit. In addition, otic and sphenethmoid are broadly co-ossified in large specimens. The basioccipital is present but rudimentary, wedged in between the exoccipital and parasphenoid and without contribution to the occipital condyles. The course of the optic, trigeminal, and facial nerves is studied in detail. The homology of the passages is assessed by means of phylogenetic arguments and comparative anatomical data, based on observations on nearest living crown groups.     

The influence of experimental deformation on craniofacial development in rats

Cranial deformation was produced experimentally in rats 8 to 40 days old for the purpose of studying the rotation of the craniofacial bones and the modification of the growth rates of the functional cranial components. One hundred and twenty four skulls (65 males and 59 females) were employed, classified as: deformed , deformed-hydrocephalic, sham-operated and controls. A midsagittal diagram was drawn for each skull and the angle subtended by each bone with respect to the vestibular plane was measured. Growth indices were worked out for both the neural skull and the facial skull. Deformation altered the rotation of the parietal, interparietal and basisphenoidal bones and restricted the rotation of the fronto-ethmo-facial complex. Alteration of the longitudinal growth rates of the dorsal and basilar components of the neurocranium and the splanchnocranium produced the persistence of the klinorynchal state.     

Non-invasive evaluation of face and motion perception in humans

The neural mechanisms for the perception of face and motion were studied using psychophysical threshold measurements, event-related potentials (ERPs), and functional magnetic resonance imaging (fMRI). A face-specific ERP component, N170, was recorded over the posterior temporal cortex. Removal of the high-spatial-frequency components of the face altered the perception of familiar faces significantly, and familiarity can facilitate the cortico-cortical processing of facial perceptions. Similarly, the high-spatial-frequency components of the face seemed to be crucial for the recognition of facial expressions. Aging and visuospatial impairments affected motion perception significantly. Two distinct components of motion ERPs, N170 and P200, were recorded over the parietal region. The former was related to horizontal motion perception while the latter reflected the perception of radial optic flow motion. The results of fMRI showed that horizontal movements of objects and radial optic flow motion were perceived differently in the V5/MT and superior parietal lobe. We conclude that an integrated approach can provide useful information on spatial and temporal processing of face and motion non-invasively.     

Measurements of postnatal growth of the skull of Pan troglodytes verus using lateral cephalograms

The postnatal growth of the viscerocranium in relation to the neurocranium of Pan troglodytes verus has been investigated using standardized lateral cephalograms. Sex and age were determined on the basis of cranial morphology and the skulls were divided into four age groups: infantile, juvenile, subadult and adult. The cephalograms were traced on transparencies and specific anatomical landmarks were identified for the measurement of lines angles and the area of the neurocranium and viscerocranium. The results showed that the skull of Pan troglodytes verus exhibits klinorhynchy. During postnatal growth it develops towards airorhynchy, but never shows true airorhynchy. In the infantile age group the measured area of the neurocranium is larger than that of the viscerocranium. The measured area of the viscerocranium increases until adulthood and is larger than that of the neurocranium in the subadult and adult group. From the results we conclude that in Pan troglodytes verus growth of the neurocranium seizes early in juvenile individuals, whereas the viscerocranium grows until adulthood. This may reflect an adaptation to the masticatory system.     

Benefits and costs of rapid growth in common murre chicks Uria aalge

While accelerated growth can be advantageous to nestling birds, there may be a tradeoff between rapid growth and resistance to food shortages. Common murres Uria aalg e are colonial seabirds that benefit from reproductive synchrony. Individuals that lay eggs late should benefit if they produce chicks capable of growing quickly and fledging synchronously with their neighbors. In this study, we controlled food provisioning of captive-hatched common murre chicks from a single subcolony and examined differences in growth between early-hatched individuals and their later-hatched neighbors. We assessed potential costs of rapid growth by comparing growth of chicks fed ad libitum with their growth under food restricted conditions. Chicks that hatched later were heavier, ate more and gained body mass more quickly than chicks that hatched earlier. Late-hatched chicks grew quickly enough to reach the same mass as their early-hatched neighbors in five days. However, chicks that grew more quickly under ad libitum food conditions grew more slowly when food was restricted. We conclude that murres that lay eggs late may synchronize their reproduction with early-laying neighbors by producing rapidly growing chicks. However, the ability to compensate for late hatching by growing quickly can be costly when food becomes limited.     

A craniofacial growth maturity gradient for males and females between 4 and 16 years of age

Differential growth of the craniofacial complex implies variation in ontogenetic patterns of development. This investigation quantifies the relative maturity—as defined by percent adult status—of nine cephalometric dimensions and stature. Analysis is based on 663 lateral cephalograms from a mixed longitudinal sample of 26 males and 25 females between 4 and 16 years of age. Graphic comparison of maturity status across the age range shows that variation is intergraded between the neural and somatic growth maturity patterns, as described by head height and stature, respectively. The maturity gradient moves from head height through anterior cranial base, posterior cranial base and maxillary length, upper facial height, corpus length, and ramus height to stature. After 9 years of age ramus height is less mature than stature. Anterior maxillary and mandibular heights diminish during transitional dentition and thereafter exhibit maturity patterns that compare to corpus length. Although females are consistently more mature than males, the gradient of variation between dimensions is sex independent.     

Effect of match or mismatch of maternal-offspring nutritional environment on the development of offspring in broiler chickens

In mammals, maternal food restriction around conception and during pregnancy results in low birth weight and an adjusted growth trajectory of offspring. If, subsequently, the offspring are born into a food-abundant environment, they are at increased risk of developing obesity, type 2 diabetes, hypertension and renal dysfunction. Here, we show similar effects of maternal undernutrition on hatch weight, growth and fat deposition in offspring of birds (domestic chicken). Both mothers and offspring were fed either ad libitum or restricted in a two-by-two factorial design, resulting in two matched and two mismatched maternal-offspring nutritional environments. Offspring of ad libitum mothers grew heavier than those of restricted mothers, possibly due to the larger muscle mass. Ad libitum-fed offspring, especially females, of restricted mothers were lighter at hatch, and were heavier and had more abdominal fat at 6 weeks of age than daughters of ad libitum-fed mothers. These results suggest a common mechanism in mammals and birds in response to a mismatch in the maternal-offspring nutritional environment. They also indicate that the common practice of restrictive feeding of the broiler breeders and subsequent ad libitum feeding of the broilers may result in reduced growth and increased abdominal fat as compared to broilers of less restricted broiler breeders.     

Craniofacial and mucopolysaccharide abnormalities in Kniest dysplasia

Serial roentgencephalograms of a male patient with Kniest dysplasia were obtained between 1 7/12 and 11 3/12 years of age and were analyzed and compared to cephalometric normative data. The patient displayed macrocephaly with increased size of the neurocranium in all three dimensions. The cranial base angle was significantly flattened, partly as a result of anterior displacement of the sella turcica. The odontoid process was short and wide. At 11 years of age there was bony fusion between the anterior arch of the atlas and the odontoid process as well as between the posterior arch of the atlas and the cranial base. The facial skeleton, including the nasal bones, infra-orbital rims, maxilla and mandible, was retropositioned relative to the anterior cranial base. The mandibular retrognathia was pronounced at an early age but improved with growth. At age 11 years the patient had a straight facial skeletal profile. Examination of the patient's 24-hour urinary excretion of keratan sulfate revealed values markedly elevated for his age. Three additional patients with Kniest dysplasia demonstrated similarly increased excretion of this glycosaminoglycan. The diagnosis of Kniest dysplasia can usually be made from roentgenograms of the extremities, the spine, and the pelvis. However, the morphologic characteristics of the head, as shown by cephalometric analysis, and the increased urinary excretion of keratan sulfate add confirmatory evidence useful in differential diagnosis.     

Facial heights: evolutionary relevance of postnatal ontogeny for facial orientation and skull morphology in humans and chimpanzees

Facial heights, i.e. the vertical distances between the superior and inferior limits of facial compartments, contribute to the orientation of the viscerocranium in the primate skull. In humans, vertical facial variation is among the main sources of diversity and frequently associated with an integrated suite of other cranio-mandibular traits. Facial heights and kyphosis are also important factors in interspecific variation and models of hominoid evolution. The ontogenetic determination of adult facial orientation and its relation to phylogenetic variation are unclear, but crucial in all previously mentioned respects. We addressed these issues in a sample of 175 humans and chimpanzees with Procrustes based geometric morphometrics, testing hypotheses of interspecific similarity in postnatal ontogenetic trajectories, early versus later ontogenetic facial pattern determination, and a developmental model of morphological integration. We analyzed the contribution of postnatal morphogenesis to adult vertical facial variation by partitioning morphological variation into a portion of pure growth allometry and a non-allometric fraction. A statistically significant difference of growth-allometries revealed that in both species growth established the adult skull proportions by vertical facial expansion, but while in chimpanzees the complete viscerocranium showed reorientation, in humans only the lower face was modified. In both species the results support a hypothesis of early facial pattern determination. A coincident emergence of morphological traits favors a hypothesis of developmental integration of the face, excluding traits of the basi- and neurocranium. Interspecific differences in integration may have implications for evolutionary studies. The present findings indicate that growth establishes the adult skull proportions and integrates principal facial orientation patterns, already there in early postnatal ontogeny.     

Tooth wear, Neanderthal facial morphology and the anterior dental loading hypothesis

The Anterior Dental Loading Hypothesis states that the unique Neanderthal facial and dental anatomy was an adaptive response to the regular application of heavy forces resulting from both the masticatory and cultural use of the anterior teeth. Heavy anterior tooth wear frequently observed in Neanderthal specimens is cited as a main source of evidence for heavy forces being applied to these teeth. From this, it might be predicted that the wear shown on the anterior teeth of Neanderthals would greatly exceed that of the posterior teeth and that this differential would be greater than in other hominins with different facial morphologies.In this paper, a new method of examining tooth wear patterns is used to test these predictions in a large assemblage of Late Pleistocene hominins and a group of recent hunter-gatherers from Igloolik, Canada. The results show that all Late Pleistocene hominins, including Neanderthals, had heavily worn anterior teeth relative to their posterior teeth but, contrary to expectations, this was more pronounced in the modern humans than in the Neanderthals. The Igloolik Inuit showed heavier anterior tooth wear relative to their posterior teeth than any Late Pleistocene hominins. There was, however, a characteristic Neanderthal pattern in which wear was more evenly spread between anterior teeth than in modern humans. Overall, the evidence presented here suggests that all Late Pleistocene hominins habitually applied heavy forces between their anterior teeth and that Neanderthals were not exceptional in this regard. These results therefore does not support the Anterior Dental Loading Hypothesis.     

Cephalometric indicators of the vertical dimension of occlusion

The aim of this investigation was to establish precise indicators of the vertical dimension of occlusion (VDO) which could be used as objective parameters in prosthodontic treatment providing exact control of the reconstructed vertical dimension of occlusion, early detection of errors and correction of the vertical dimension of occlusion during complete denture manufacturing. A total of 60 lateral cephalometric radiographs of subjects with natural dentition and class I skeletal jaw relationship, of Serbian nationality from the region of Vojvodina, were included in the investigation. Thirty subjects were males, and thirty females, their age range was 20 to 29 years. Cephalometric analysis was performed by using "Dr. Ceph" computer software (FYI Technologies, GA, USA). By evaluation of the craniofacial complex in subjects with natural dentition, horizontal dentofacial developmental growth was established in the examined sample and it was based on the relationship between the posterior and anterior total facial height (S-Go:N-Me, female X=68.96%, male X=72.8%) and statistically significant differences were found between the sexes in almost all linear dimensions and in the relation between the posterior and the anterior total facial height. Highly significant differences (p<0.001) between the sexes were found in regard to anterior total facial height (N-Me, male X=120.75 mm, female X=112.72 mm) and the anterior lower facial height (ANS-Me, male X=67.87 mm, female X=61.50 mm) (p<0.05). The proportions of the upper and lower anterior facial heights (N-ANS:ANS-Me, male X=79.36%, female X=80.63%) were within normal values in both sexes. Facial harmony existed both in men and women. Cephalometric study of the subjects with complete natural dentition included in this study provided important and specific parameters for optimal reconstruction of vertical dimension of occlusion in the treatment of edentulous patients.     

Poor growth prior to early childhood: decreased health and life-span in the adult

Previous studies in animal populations have shown that stunted neural and thymolymphatic growth early in development may result in permanently impaired neural and immune function, decreased body growth, vertebral wedging, and decreased life-span. In the human adult, small vertebral neural canal (VNC) diameters may reflect early stunted neural and immune development and impaired function that leads to decreased health (inferred by greater vertebral wedging) and life-span in the adult. VNC, which complete their growth by early childhood (age 4), are markers of early development in adults. On the other hand, features following general body growth, such as height, weight (represented here by vertebral body height) continues to grow until young adulthood. They are less reliable, because they readily experience catch-up growth (even in chronically stressed populations) and, unlike VNC, may mask poor early growth. To test associations between early growth and adult health and life-span in humans, we measured 2,060 VNC, vertebral heights, vertebral wedging, nerve-root tunnel lengths, severity of vertebral osteophytosis, and ages at death in 90 adult (aged 15-55 years) prehistoric skeletons (950-1300 A.D.). Tibial lengths were also measured in a subsample (n = 30). Multivariate, bivariate, and nonparametric analyses showed that small VNC are significantly associated with greater vertebral wedging and decreased life-span (P less than 0.05-0.00001). VNC are independent of vertebral body heights and tibial lengths (general body growth). VNC, but not statural components, are useful in predicting adult health, presumably because they reflect neural and immune development and do not readily experience catch-up growth. Thus, longitudinal retrospective measures of early growth and adult health were systematically linked within individuals regardless of confounding factors operating over the 350-year time period. Since this research was completed, this model has repeatedly been independently confirmed in four living urban industrial populations. Longitudinal retrospective analysis was employed together with direct measures of VNC, neural and immune function. Together these results suggested that it may be essential to improve growth prior to early childhood in order to maximize adult health and life-span.     

Orthocephalization in the postweaning squirrel monkey

Twenty male squirrel monkeys (Saimiri sciureus boliviensis) raised in captivity were allotted to one of the following groups: weanling control (C6) sampled at 6 months of age; young control (C24) fed ad libitum on a control diet and killed at 24 months of age; and malnourished (M24) fed ad libitum on a low-protein diet and sampled at 24 months of age. Cranial points and the lateral semicircular canals were marked. On each skull, a strict lateral teleradiograph was taken, and the lengths of the midsagittal chords and their angles with respect to the vestibular line were measured. Age changed the lengths in about 70% of the chords and more than 50% of the angles. Malnutrition arrested about 50% of the lengths, but the angles were practically not affected. It is concluded that the postweaning Saimiri sciureus undergoes orthocephalization according to a general pattern already observed in rodents and suggested for pongids. Postweaning malnutrition affected growth in size but not shape changes related to the orthocephalization of the Saimiri skull. © 1996 Wiley-Liss, Inc.     

Sizes and daily growth rates of two algal phytoplankters in the field

SUMMARY 1. Measurements of daily growth rates, colony widths and lengths and cell widths and lengths were made on Fotterella tetrachlorelloides Buck and Staurastrum longiradiatum West & West (Chlorophyceae), collected from an eutrophic reservoir close to Madrid (Spain) on nine consecutive days of June 1983.
2. F. tetrachlorelloides exhibited growth followed by a period of decay, whilst S. longiradiatum grew more or less continuously throughout the observations.
3. A colony length-width relationship was statistically significant throughout the growth period of F. tetrachlorelloides , but not when the population was decaying. This relationship was always statistically significant in S. longiradiatum . There was an inverse relationship between volume and daily growth rate in S. longiradiatum , but no such correlation was found in F. tetrachlorelloides .
4. The time course of statistical volume distributions and daily growth rates suggested that F. tetrachlorelloides was undergoing clonal ageing during the study.