Mandibular ramus flexure: A new morphologic indicator of sexual dimorphism in the human skeleton

In the skeleton, male and female characteristics lie along a continuum of morphologic configurations and metric values. Size alone is not the best indicator of sex. In contrast, morphologic differences that arise from genetically sex-linked growth and development allow better separation of the sexes. This study presents a new morphologic indicator of sexual dimorphism in the human mandible. A sample of 300 mandibles from adults of known sex primarily from the Dart collection was analyzed. Of these, 100 were found to have obvious bony pathologies and/or excessive tooth loss (“pathologic” sample). Thus, the normative sample consisted of 200 individuals (116 males, 84 females). Examination of morphologic features led to the discovery of a distinct angulation of the posterior border of the mandibular ramus at the level of the occlusal surface of the molars in adult males. Flexure appears to be a male developmental trait because it is only manifest consistently after adolescence. In most females, the posterior border of the ramus retained the straight juvenile shape. If flexure was noted, it was found to occur either at a higher point near the neck of the condyle or lower in association with gonial prominence or eversion. In the normative sample, overall prediction accuracy from ramus shape was 99%. When the “pathologic” sample was analyzed separately, 91.0% were correctly diagnosed. Because the African samples were overwhelmingly black, this trait was also tested on American samples (N = 247) of whites (N = 85), Amerinds (N = 66), and blacks (N = 96) that included a mix of healthy individuals and those with extensive tooth loss and evidence of pathology. The results were nearly identical to those of the “pathologic” African sample, with accuracies ranging from about 91% in whites and blacks to over 92% in Amerinds. Total accuracy for all African and American samples combined (N = 547) is 94.2%. In conclusion, at 99%, sexing from the shape of the ramus of a healthy mandible is on a par with accuracy attainable from a complete pelvis. Moreover, there is no record that any other single morphologic or metric indicator of sex (that has been quantified from the adult skeleton) surpasses the overall accuracy attained from the more representative mixed sample produced by combining all groups assessed in this study. The usefulness of this trait is enhanced by the survivability of the mandible and the fact that preliminary investigations show that the trait is clearly evident in fossil hominids. © 1996 Wiley-Liss, Inc.     

Karyotypes of three rat species (Mammalia: Rodentia: Muridae) from Hainan Island, China, and the valid specific status of Niviventer lotipes

The karyotypes of three rat species from Hainan Island, China, were examined. Niviventer fulvescens (Gray, 1847) had 2n=46 and FN=64, similar to the karyotypes reported for N. fulvescens from Southeast Asia, while Niviventer lotipes () had 2n=52 and FN=66, which is distinct from the known karyotypes of other Niviventer species. Niviventer lotipes was recently considered conspecific with N. tenaster (), but the two were found to have extremely different karyotypes (2n=52 and FN=66 in N. lotipes; 2n=46 and FN=54 in N. tenaster). Therefore, in this paper N. lotipes is considered a valid species for the first time; it is distinct from N. tenaster and endemic to Hainan Island, where N. lotipes is differentiated from N. fulvescens by larger body and skull sizes, a shorter tail, and darker coloration. Rattus nitidus (Hodgson, 1845) from Hainan Island had 2n=42 and FN=62, which is similar to the reported karyotypes of conspecific populations in Southeast Asia.     

Mark-recapture and Moran curve estimates of the survival probabilities of an island population of tsetse flies Glossina morsitans morsitans (Diptera: Glossinidae)

A study on populations of Glossina morsitans morsitans Westwood on Antelope Island, Lake Kariba, Zimbabwe provided Jolly-Seber (J-S) mark-recapture estimates of adult survival and Moran curve estimates of the overall survival of all developmental stages. For females, Moran survival estimates derived using ox fly-round catches showed similar trends to, but were more variable than, those calculated from J-S population estimates. Regression of one set on the other removed only 26% of the variance. Undue emphasis should not be placed on small changes in Moran survival estimates based on sequences of catches. Catch data cannot provide Moran estimates of male survival probabilities and no comparison is thus possible with estimates from the J-S data. The J-S and the Moran approaches were combined to estimate survival probabilities of the immature stages of male and female tsetse. The overall survival per three-week period averaged 45% for males and 59% for females, comprising mature adult survivals of 27 and 46%, and pooled survivals of immature stages of 59 and 77%, respectively. The high survival of immature flies is due to the sheltered, inactive nature of pupal life. Adult and overall survival probabilities were highly correlated in males (r(2) = 0.61) but less so in females (r(2) = 0.24) where capture rates were lower and variance in the results greater. Immature and overall survival was more highly correlated for both sexes, with r(2) = 0.77 and 0.53 for males and females respectively. When a fixed pupal mortality of 1% per day was assumed, estimates of the survival of young adult males suggested that these were even lower than the survival of mature flies at the harshest times of the year, but were not markedly different when overall survival was high. Assuming equal mortality in all adults enabled the estimation of pupal survival. These had high variances but there was no evidence of any difference between the survival probabilities of male and female pupae.     

Bioarchaeological evidence for trophy-taking in prehistoric central California

Fourteen adult burials in a large (N = 224) prehistoric central California cemetery (CA-SCL-674) lack forearm bones. Twelve of these otherwise well-articulated primary interments have distal humeri bearing cutmarks with a distribution like that seen in fur seals butchered by Native Californians. Most of the burials with missing forearms are young adult males, a demographic profile that differs significantly from the full sample. Three of these males show evidence of perimortem trauma in addition to forearm amputation. Drilled and polished human radii and ulnae were recovered from the CA-SCL-674 cemetery in archaeological contexts separate from burials with missing forearms. A warfare-related trophy-taking practice is strongly suggested by these bioarchaeological data. Based on these data, it seems likely that 20% (N = 10) or more of the adult males (N = 59) in this population were victims of violence. Evidence of perimortem violence was much less common among women, with only about 2% (N = 2) of adult females (N = 86) subjected to trophy-taking. Examination of museum collections produced further evidence for perimortem forearm amputation among the Native American inhabitants of this area during the transition between the Early and Middle periods. The emergence of more hierarchical social systems during this period may have fostered warfare-related trophy-taking as a symbolic tool for enhancing the power and prestige of individuals within competing social groups.     

Sex-specific differences in body condition indices and seasonal mass loss in Tufted Puffins

ABSTRACT.   Reduced prey availability can affect the growth and survival of nestling seabirds. However, few studies have demonstrated similar effects on indices of adult body condition. We examined body condition and seasonal mass loss of breeding adult male and female Tufted Puffins ( Fratercula cirrhata ) at Chiniak Bay, Kodiak Island, Alaska, in 2004–2005. We determined sex using genetic analysis, developed a discriminant function to determine sex using morphometric measurements, and examined the body condition of adult males and females relative to the growth rates of their offspring. We found that morphological measurements were only moderately useful for sexing Tufted Puffins, with 74% of adults ( N = 176) correctly classified. We also found that the relationship between adult body mass and size differed between sexes and conclude that body condition indices must be calculated separately for each sex to avoid inter- and intrasexual bias. Body condition of male and female Tufted Puffins declined during the chick-rearing period. However, body condition of females did not differ between years, whereas male condition declined to a greater degree during 2004 when the mass of young at fledging was significantly lower. Although these results suggest that adult male Tufted Puffins sacrifice their own body condition in years of diminished nestling growth and females do not, reasons for this apparent intersexual difference in reproductive strategies remain unclear.     

Embryonic lethality leads to hybrid male inviability in hybrids between Drosophila melanogaster and D. santomea

The study of the morphological defects unique to interspecific hybrids can reveal which developmental pathways have diverged between species. Drosophila melanogaster and D. santomea diverged more than 10 million years ago, and when crossed produce sterile adult females. Adult hybrid males are absent from all interspecific crosses. We aimed to determine the fate of these hybrid males. To do so, we tracked the development of hybrid females and males using classic genetic markers and techniques. We found that hybrid males die predominantly as embryos with severe segment‐specification defects while a large proportion of hybrid females embryos hatch and survive to adulthood. In particular, we show that most male embryos show a characteristic abdominal ablation phenotype, not observed in either parental species. This suggests that sex‐specific embryonic developmental defects eliminate hybrid males in this interspecific cross. The study of the developmental abnormalities that occur in hybrids can lead to the understanding of cryptic molecular divergence between species sharing a conserved body plan.     

Does urban poverty increase body fluctuating asymmetry?

Perturbations during development leave enduring signs on the adult body. Fluctuating asymmetry (FA) is a good bio-indicator of stress during ontogeny. The aim of this study is to determine the effect of urban poverty on the fluctuating asymmetry of young Turkish males. Young males from a lower socioeconomic group (N = 140, Mean age = 18.17 +/- 0.61) were selected from slum areas of Ankara, the capital of Turkey, where urban poverty is intense. An upper socioeconomic group, on the other hand, consisted of students from two private colleges and included children from some of the richest families in Turkey (N = 120, Mean age = 18.08 +/- 0.54). Eight anthropometric traits of all subjects were measured. Considering the seven measurements demonstrate ideal FA, the individuals living in poor areas of the city displayed higher FA. The discrepancy between the two groups was even greater for a measure of composite FA. In conclusion, poor living conditions in Ankara, where urban poverty is intense, adversely impact the developmental stability of young Turkish males.     

Hybrid Dysgenesis in DROSOPHILA MELANOGASTER: Morphological and Cytological Studies of Ovarian Dysgenesis

A type of intraspecific hybrid sterility, between two strains of Drosophila melanogaster, referred to as GD (gonadal dysgenesis) sterility, is observed when females from a type of strain called M are crossed with males from a second type called P. Absence of egg-laying is characteristic of female GD sterility and its manifestation is conditional on high developmental temperatures. Morphological and cytological studies of GD sterile females are described. These individuals were normal in body size and external appearance. No defects in sperm storage were observed. Both adult and larval ovaries were drastically reduced in size in comparison with control ovaries. This ovarian dysgenesis was sometimes unilateral, but more frequently it was bilateral, particularly in females developing at the highest test temperature. The ovarioles of dysgenic ovaries contained no vitellaria; the germaria lacked any cells resembling the cystocyte clusters of normal ovaries. It is concluded that sterility results from an early blockage in ovarian development, rather than from atrophy of previously developed structures. Possible mechanisms for this developmental arrest are discussed.     

Life stress on the Roman limes in continental Croatia

The purpose of the paper is to analyze and compare the demographic profiles and disease frequencies between a skeletal series from Zmajevac, a settlement on the Danubian limes, and a composite «non-limes» skeletal series consisting of human osteological remains from three large urban settlements to the west of the limes; roman Mursa (modern Osijek), Cibalae (Vinkovci) and Certissia (Štrbinci). To determine if life stresses were different in settlements on the limes the age and sex distribution in Zmajevac was compared to the composite «non-limes» series. All skeletons were also analyzed for the presence of dental pathology, dental enamel hypoplasia, cribra orbitalia, trauma, and physical stress.

Data collected from the skeletal series show that, with the exception of some indicators of physical stress, no significant differences in quality of life is evident. Both series are characterized by an underrepresentation of subadults from the youngest age category and by similar average adult male and female ages at death. In Zmajevac the average ages at death for adult males and females were 40.0 and 39.0 years respectively, in the composite «non-limes» series 37.4 years for both males and females. The frequencies of dental disease, subadult stress indicators, and trauma are similar in both series. The only consistent difference between the two series is noted in the frequencies of skeletal markers of physical stress, in particular the frequencies of vertebral osteoarthritis and Schmorl's defects. Total male and total female vertebral osteoarthritis frequencies in the two series are significantly different, as is the difference in total male frequencies of Schmorl's defects. Young adult males in the Zmajevac series seem to have been experiencing particularly heavy physical strain on the vertebral column. They exhibit significantly higher frequencies of both vertebral osteoarthritis and Schmorl's defects than young adult males from the composite non-limes series.     

Radioimmunoassay of the A prostaglandins

Antibodies to the (PGA) prostaglandin A were produced in rabbits immunized with a conjugate of PGE2 covalently linked to (BSA) bovine serum albumin by reaction with carbodiimide reagent. A radioimmunoassay was developed using dextran-coated charcoal to separate the free from antibody bound PGA1-3H. The sensitivity of the method was found to be 100 picograms/ml of plasma. Ethyl acetate was used for extraction of plasma and the various classes of PGs were separated by silicic acid column chromatography. Recovery of PGA1-3H throughout the entire procedure was 65-75%. The antibody showed progressively decreasing affinity to PGA2, PGA1, PGE2, PGE1, PGB2, and PGF2alpha, respectively. The mean plasma PGA level in adult males (N=13) was found to be 1.39 + or - 0.55 ng/ml, and 1.62 + or - 0.52 ng/ml in adult females (N=7). Corresponding plasma and serum samples were found to give essentially similar results. Plasma PGA levels in adult males treated with indomethacin for rheumatoid arthritis were 0.18 + or - 0.15 ng/ml (P 0.001 in comparison with the normal adult males). This method is sufficiently sensitive, precise, and rapid to allow the routine estimation of the PGAs in biological samples.     

Reproductive hormone profiles in captive male orangutans: Implications for understanding developmental arrest

For many years researchers have described some male orangutans as “subadult.” These males are of adolescent to adult age and are reproductive, but have little to no secondary sexual trait development. Until now the only endocrine study of this arrest of secondary sexual trait development was performed by Kingsley (1982, 1988). She found that “subadult” or arrested males have lower testosterone levels than similar age developing adolescents or adult males. In this study, urine samples were collected over a two-year period from 23 captive male orangutans in order to more fully define male endocrine profiles. Three study males were juveniles, seven were arrested adolescents, six were developing adolescents, and seven were mature adults. Morning samples were analyzed by radioimmunoassay for levels of testicular steroids and gonadotropins and group hormone profiles were compared by analysis of variance. Results illustrate that arrested adolescent orangutans have significantly lower testosterone and dihydrotestosterone (DHT) levels than developing adolescents, but significantly higher levels than juveniles. Luteinizing hormone (LH) levels also differed between arrested and developing adolescents, with arrested males having lower levels. However, follicle stimulating hormone (FSH) levels were similar in both morphs of adolescent male. The overall hormone profiles for arrested and developing adolescent male orangutans suggest that arrested males lack levels of LH, testosterone, and DHT necessary for development of secondary sexual traits. However, they have sufficient testicular steroids, LH, and FSH to fully develop primary sexual function and fertility. These endocrine data help define alternative developmental pathways in male orangutans. The authors discuss the relationship between these developmental pathways and male orangutan reproductive strategies, and hypothesize about their prepubertal socioendocrine determination. Am J Phys Anthropol 109:19–32, 1999. © 1999 Wiley-Liss, Inc.     

Survival,density and population composition of bellbirds (Anthornis melanura) on the Poor Knights Islands,New Zealand

Abstract

Annual survival by age, sex and population size and structure were estimated for bellbirds (Anthornis melanura) from a banding study undertaken on 66 ha Aorangi Island, the Poor Knights Islands, during the period 1978–86. The most parsimonious model showed that survival varied little with age and between years, and survival of males was significantly greater than that of females. Recapture probabilities of males and females were similar, but did vary with age and among years. There was a greater proportion of adult males than adult females and sub‐adult males and females in the population, and among adults the male bias in the population was greater during the breeding season than at other times of the year. The high density of bellbirds on the Poor Knights and larger size of males may explain the reduced survival of females relative to that of males.     

Dialects of northern elephant seals, Mirounga angustirostris: Origin and reliability

Threat vocalizations of adult male northern elephant seals, Mirounga angustirostris, were recorded over a 5-year period to determine whether local dialects previously reported in this species are reliable. These results were obtained: (1) The mean pulse rate at Año Nuevo Island, which was colonized in 1961, has increased every year from 1968 to 1972 but still remains slower than the mean pulse rate of all southern rookeries. (2) The pulse rate of individual adult males does not vary significantly for at least 3 years. (3) Forty-three per cent of the breeding males on Año Nuevo Island are immigrants from southern populations each of which has a faster mean pulse rate than Año Nuevo Island. (4) The pulse rate at San Miguel Island, a large rookery which receives few immigrants, did not change significantly from 1969 to 1972. A model is advanced to explain the data and account for geographical variation in learned vocalizations of species whose populations are expanding.     

Homologies of the stapedial artery in humans, with a reconstruction of the primitive stapedial artery configuration of Euprimates

Data drawn from the perspectives of paleontology, comparative anatomy, embryology, teratology, and normal adult variation were analyzed with nine homology criteria in order to determine the homologues of the stapedial artery in adult humans. It was determined that 1) the stem of the stapedial artery does not persist within the cranial cavity; 2) the stem of the ramus inferior is retained in its entirety and forms the upper portion of the stem of the middle meningeal artery; 3) the proximal part of the ramus infraorbitalis is normally absent and is replaced by a collateral shunt arising from the ramus mandibularis; 4) the ramus mandibularis is retained and forms the lower portion of the middle meningeal stem and the inferior alveolar artery; 5) the most proximal portion of the maxillary artery is formed by an anastomotic shunt connecting the external carotid artery to the ramus mandibularis; 6) the anterior division of the ramus superior is normally present and well developed; 7) the posterior division of the ramus superior is present in many individuals; and 8) the junction of the two divisions of the ramus superior with the ramus inferior usually migrates to the floor of the middle cranial fossa. The range of human arterial patterns, and those of all other euprimates, can be derived from a hypothetical primitive pattern that is very similar to that of primitive rodents. In this pattern, the stapedial artery stem enters the middle cranial fossa and trifurcates into the anterior and posterior divisions of the ramus superior and the ramus inferior. In their evolution, strepsirhines initially lose the ramus inferior and haplorhines initially reduce the stapedial artery stem.     

Relationships between elevation, reproduction and the hematocrit level of brown-headed cowbirds

Hematocrit, furcular fat level and oviducal egg presence were determined for 267 brown-headed cowbirds (Molothrus ater) at eight sites ranging from 15 to 2390 m above sea level in California. Near the end of the breeding season males at a mid-elevation site (1250 m) possessed higher hematocrits than females, but there was no difference between yearling and adult males. Birds were bled during three 11-day periods beginning 1 May 1984 at one montane site (2075 m). The percentage of females with oviducal eggs increased significantly from 0 to 10 to 67% and the mean female hematocrit increased from 0.54 to 0.56 and then decreased significantly to 0.52. The hematocrit of males increased significantly from 0.54 to 0.57 and then remained level during the final period. Correlations were calculated between mean hematocrit and elevation for males (r = 0.94, N = 8 sites, P less than 0.001), females (r = 0.96, N = 7 sites, P less than 0.001) and juveniles (r = 0.99, N = 4 sites, P less than 0.01).     

Isotopic evidence for breastfeeding and possible adult dietary differences from Late/Sub-Roman Britain

Historical documents indicate that breastfeeding and weaning practices have fluctuated in England through history. In order to obtain evidence for general breastfeeding patterns in Late/Sub-Roman Britain, stable carbon and nitrogen isotope values were measured in juvenile and adult skeletons (n = 87) from the cemetery of Queenford Farm, Dorchester-on-Thames, Oxfordshire. As the site contained few individuals between 0-1.5 years of age, it was not possible to determine the initial timing for the introduction of weaning foods. Between ages 2-4 years, the mean +/- SD delta(13)C results (-20.2 +/- 0.3 per thousand) are significantly more negative (t = -4.03, P < 0.001) compared to adult females (-19.7 +/- 0.3 per thousand). This is interpreted as evidence of a different diet being fed to children during weaning. After age 2, the delta(15)N values gradually decline, indicating complete cessation of breastfeeding by 3-4 years. Among adults, stature (males = 1.68 +/- 0.06 m; females = 1.58 +/- 0.07 m) and sexual dimorphism (106) were low, suggesting that the population was possibly under environmental stress. The delta(13)C results for adults are similar, but females show a small but statistically significantly (t = -2.86, P < 0.01) lower mean delta(15)N value (9.9 +/- 0.9 per thousand) compared to males (10.6 +/- 0.5 per thousand). These lower female delta(15)N values possibly reflect the different physiology of the sexes (pregnancy and/or lactation) or the reduced consumption of animal/fish protein by women, and this may have been influenced by individual preference, family needs, or societal values of the era.     

Catch-up growth in Japanese quail (Coturnix Japonica): relationships with food intake, metabolic rate and sex

The effects of early environmental conditions can profoundly affect individual development and adult phenotype. In birds, limiting resources can affect growth as nestlings, but also fitness and survival as adults. Following periods of food restriction, individuals may accelerate development, undergoing a period of rapid “catch-up” growth, in an attempt to reach the appropriate size at adulthood. Previous studies of altricial birds have shown that catch-up growth can have negative consequences in adulthood, although this has not been explored in species with different developmental strategies. Here, we investigated the effects of resource limitation and the subsequent period of catch-up growth, on the morphological and metabolic phenotype of adult Japanese quail (Coturnix japonica), a species with a precocial developmental strategy. Because males and females differ in adult body size, we also test whether food restriction had sex-specific effects. Birds that underwent food restriction early in development had muscles of similar size and functional maturity, but lower adult body mass than controls. There was no evidence of sex-specific sensitivity of food restriction on adult body mass; however, there was evidence for body size. Females fed ad lib were larger than males fed ad lib, while females subjected to food restriction were of similar size to males. Adults that had previously experienced food restriction did not have an elevated metabolic rate, suggesting that in contrast to altricial nestlings, there was no metabolic carry-over effect of catch-up growth into adulthood. While Japanese quail can undergo accelerated growth after re-feeding, timing of food restriction may be important to adult size, particularly in females. However, greater developmental flexibility compared to altricial birds may contribute to the lack of metabolic carryover effects at adulthood.     

Ecology and reproductive patterns of the agamid lizard Japalura swinhonis on an east Asian island, with comments on the small clutch sizes of island lizards

I describe the habitat use, diet, and the male and female reproductive cycles of Japalura swinhonis, an oviparous agamid lizard inhabiting Orchid Island, a tropical island off the southeastern coast of Taiwan. Ninety percent of lizards (n=126) were observed on tree trunks or at the forest edge. The diet of J. swinhonis on Orchid Island consisted mostly of hymenopterans (53.33%) and orthopterans (16.67%). The mean snout-vent length (SVL) of adult males was 74.58 (n=89) and that of females was 69.31 (n=37) mm. Females exhibited a long vitellogenic period from November to February, with parturition occurring from March to October. The onset of vitellogenesis did not correlate with the mass of the female fat bodies. Females produced two to five eggs per clutch, and clutch size was not correlated with SVL. Two clutches were recorded during a single year in some individuals. Clutch size in J. swinhonis was compared with that in other Japalura species. Clutch sizes of Japalura species are larger in mainland China than on insular Taiwan. Clutch size is also mainly affected by environmental constraints, and smaller clutch sizes are probably affected by predators on Orchid Island.     

Characterization of defects in adult germline development and oogenesis of sterile and rescued female hybrids in crosses between Drosophila simulans and Drosophila melanogaster

Crosses between Drosophila melanogaster and D. simulans normally result in progeny that are either inviable or sterile. Recent discovery of strains that rescue these inviability and sterility phenotypes has made it possible to study the developmental basis of reproductive isolation between these two species in greater detail. By producing both rescued and unrescued hybrids and examining the protein product staining patterns of genes known to be involved in early germline development and gametogenesis, we have found that in crosses between D. simulans and D. melanogaster, hybrid female sterility results from the improper control of primordial germline proliferation, germline stem cell maintenance, and cystoblast formation and differentiation during early oogenesis. Rescued hybrid females are fertile, yet they generally have lower amounts of adult germline from the outset and show a premature degeneration of adult germline cells with age. In addition, older rescued hybrid females also exhibit mutant egg phenotypes associated with defects in dorso-ventral patterning which may result from the improper partitioning of cytoplasmic factors during early oogenesis that could stem from the early defect. Although a variety of germline and oogenic defects are described for the hybrid females, all of them can potentially result from the same underlying primary defect. Hybrid males from these same crosses, on the other hand, have no detectable germline in adult reproductive tissues, even when hybrid sterility rescue strains are used, indicating that male sterility and female sterility stem from distinctly different developmental defects.