Skeletal development of non-institutionalized children with low Intelligence Quotients

Children of both sexes with mild mental retardation show delays in skeletal maturation and cortical bone growth, but boys in general are more affected than girls. Skeletal age for both sexes is below normal in the younger age groups, but approaches normality at adolescence. None of the measures of IQ is significantly correlated with any of the regional measures of skeletal age in the hand-wrist. The approach toward normality of skeletal development in this population at adolescence is reflected in their normal time of first appearance of the adductor sesamoid. Anomalies of the hand-wrist reflect irregularities in comparing normal and low-IQ children. Only brachymesophalangy V displays significantly higher frequencies in the low-IQ groups. Due to the cross-sectional nature of the study and the different methods of classifying anomalies, little can be said about the other comparisons. Growth in cortical bone reflects a consistent trend for both the humerus and second metacarpal. While measures of total diameter and total cross-sectional area do appear to be below normal standards, the measures of the marrow do not. This finding accounts for a decreased cortical bone thickness and cross-sectional area in the low-IQ sample. All measures of the humerus correlate significantly with two IQ scores in the boys and all three scores in the girls. Measures of the total metacarpal and marrow area show significant correlations with the three IQ scores among low-IQ boys, while only measures of total metacarpal area show significant correlations with verbal IQ in low-IQ girls. The degree of mental deficiency, then, is only irregularly associated with deficits of bone size for age.     

Relative dental maturity and associated skeletal maturity in prehistoric native Americans of the Ohio valley area

Estimation of age-at-death of subadults in prehistoric skeletal samples based on modern reference standards rests on a number of assumptions of which many are untestable. If these assumptions are not met error of unknown magnitude and direction will be introduced to the subadult age estimates. This situation suggests that an independent estimate or estimates of age-related features, free of most of the assumptions made when using modern reference standards may be useful supplements in evaluating the age of subadults in prehistoric samples. The present study provides an internally consistent, population-specific measure of maturity for prehistoric Ohio valley Native Americans based on the seriation of dental development that may be used as a supplement to age-estimation. The developing dentition of 581 subadults from eight Ohio valley prehistoric-protohistoric groups was seriated within and among individuals resulting in a sequence of tooth development and a sequence of individuals from least to most mature. Dental maturity stages or sorting categories were then defined based on exclusive, easily observable, and highly repeatable tooth-formation stages. Tooth eruption (into occlusion), bone lengths, and fusion of skeletal elements are summarized by dental maturity stage. This procedure provides maturity estimates for skeletal features ordered by dental maturity stages derived from the same sample thus making explicit the relationship between dental and skeletal maturity.     

Evidence for multiple year classes of the giant Australian cuttlefish Sepia apama in northern Spencer Gulf, South Australia

Giant Australian cuttlefish form a mass spawning aggregation at a single site in northern Spencer Gulf (NSG) in South Australia every austral winter. Samples of cuttlefish were collected from this region over three consecutive years. Analysis of regular growth increments in the cuttlebones of these individuals, revealed a polymorphism in growth pattern for both sexes. Three distinct “bone patterns” were identified based on the variation in increment widths over the lengths of the bones. All bones analysed conformed to one of the three bone patterns, and the increment width patterns were consistent between years. Interpretation of the patterns, suggested that Sepia apama have two alternative life cycles. The first involves rapid juvenile growth during the first summer after hatching, with maturity reached within 7–8 months. These individuals return to spawn in their first year as small individuals. The second life cycle involves much slower juvenile growth during the first summer, with maturity deferred until their second year, when they return to spawn as much larger individuals. Thus, the age compositions of populations of S. apama in the NSG appear to consist of two year classes for both sexes.     

Life-history strategies of Acrossocheilus fasciatus (Barbinae, Cyprinidae) in the Huishui Stream of the Qingyi watershed, China

Life-history traits of Acrossocheilus fasciatus were examined using 384 specimens collected monthly during May 2009 and April 2010 in the Huishui Stream of the Qingyi watershed, China. Using scales for age determination, female and male fish comprised five and four age groups, respectively. The monthly changes in marginal increment ratio suggested that annuli on scales were formed during March through May. Total lengths back-calculated significantly increased with age for both sexes and varied significantly between the two sexes at each age. The fact that females had larger body size and grew faster than males indicated the sexual size dimorphism for this species. Both sexes got their 50% maturity at age 3, when females and males were 105.3 and 112.1?mm total length, respectively. Based on the monthly changes in the gonado-somatic index and egg-development process, fish spawned from April through August. Absolute fecundity ranged from 295 to 3,573 eggs per fish and increased significantly with age. But relative fecundity, ranging from 11.77 to 69.96?eggs/g, was not significantly different among age groups. Compared with the life-history traits of an upstream population in the Puxi Stream (a headwater stream within this study watershed), the downstream population of A. fasciatus in the Huishui Stream (a 4th-order stream) exhibits larger body size, faster somatic growth, later sexual maturity, and lower reproductive investment. These variations in life-history strategies between the two populations could perhaps be explained by the spatial heterogeneity in habitat environment along the upstream–downstream gradient in this watershed.     

Pelvic growth: ontogeny of size and shape sexual dimorphism in rat pelves

The mammalian pelvis is sexually dimorphic with respect to both size and shape. Yet little is known about the differences in postnatal growth and bone remodeling that generate adult sexual dimorphism in pelvic bones. We used Sprague-Dawley laboratory rats (Rattus norvegicus), a species that exhibits gross pelvic size and shape dimorphism, as a model to quantify pelvic morphology throughout ontogeny. We employed landmark-based geometric morphometrics methodology on digitized landmarks from radiographs to test for sexual dimorphism in size and shape, and to examine differences in the rates, magnitudes, and directional patterns of shape change during growth. On the basis of statistical significance testing, the sexes became different with respect to pelvic shape by 36 days of age, earlier than the onset of size dimorphism (45 days), although visible shape differences were observed as early as at 22 days. Males achieved larger pelvic sizes by growing faster throughout ontogeny. However, the rates of shape change in the pelvis were greater in females for nearly all time intervals scrutinized. We found that trajectories of shape change were parallel in the two sexes until age of 45 days, suggesting that both sexes underwent similar bone remodeling until puberty. After 45 days, but before reproductive maturity, shape change trajectories diverged because of specific changes in the female pelvic shape, possibly due to the influence of estrogens. Pattern of male pelvic bone remodeling remained the same throughout ontogeny, suggesting that androgen effects on male pelvic morphology were constant and did not contribute to specific shape changes at puberty. These results could be used to direct additional research on the mechanisms that generate skeletal dimorphisms at different levels of biological organization.     

Height, weight, and lines of arrested growth in young Guatemalan children

A cross-sectional study of height, weight and skeletal maturity as judged from radiographs of hand and wrist, of 1,412 children under seven years of age (694 boys and 718 girls) living in rural Guatemala was performed. Height and weight were compared to standards prepared by the Institute of Nutrition of Central America and Panama (INCAP). Skeletal age was assessed by the Tanner-Whitehouse and the Greulich and Pyle methods. All x-rays were read by the senior author. The children surveyed were significantly shorter and lighter than well noruished Guatemalan children. Differences were evident by age six months and at a maximum by age five years. Both methods showed skeletal age to lag behind chronological age so that the Guatemalan rural children mature at slower rates than either the British children or the Ohio, U.S.A., children, from whom the two sets of standards were developed. Children of both sexes with radio-opaque transverse lines at the metaphysis showed a consistent tendency to be shorter than children without such lines. Boys but not girls showed similar trends for weight. In general, the data are consistent with the view that the physical development in boys is more severely retarded by an adverse environment than that of girls.     

Bone growth aud development of secondary ossification centers of extremities in the cynomolgus monkey (Macaca fascicularis).

The development of so-called long bones in the extremity has been studied roentgenographically in forty-seven males and fifty-one females cynomolgus monkeys bred and reared at the National Institute of Health. The age of the females ranged from five months to eight years and nine months, and that of the males was from four months to seven years. In addition, the fetuses of six to twenty weeks of gestation age were examined for the time of appearance of ossification centers. As the biological parameters concerning body growth, the body weight and the bone length were measured and the secondary ossification centers were scrutinized and assessed the maturity process on the basis of the criteria that divided the state into eleven stages. Also the allometric analyses of body weight against bone length was conducted. Most of the secondary ossification centers except the proximal fibulal epiphysis appeared during the period from the prenatal stage (15-20 weeks of gestationage) to the postnatal one (several months of age). From four to five months of age, many ossification centers had developed to some extent. But, the appearance of proximal fibulal epiphysis was delayed and often lacking until 10 months of age in female and one year and three months of age in male. The earliest epiphyseal fusion was observed at the distal humeral epiphysis in both sexes. The latest epiphyseal fusion was observed at the distal ulnal epiphysis in both sexes and at the distal ulnal and radial epiphyses in female. From this study, the time of fusion was at five and three guarters years of age in females and at six and a half years of age in males. As a result, it is suggested that the estimation of animal's age might be put to practical use by introducing the assessing method that the score was given from the observation of the secondary ossification center.     

Age, growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains

Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.     

Fat patterning in Papua New Guineans: effects of age, sex and acculturation

For the renewed interest in fat patterning to be fruitful, more information on the biology of fat patterning, particularly normative data are required. Nine skinfold thicknesses were measured in 2312 coastal and highland Papua New Guineans of all ages undergoing acculturation. Principal component analysis of the skinfold data revealed components of fatness and fat patterning. First component scores were typical of the changes in fatness with age and the sex differences expected in these populations. Second component scores of limb-trunk fat patterning showed marked changes with age in both sexes but they stabilised in adulthood. This pattern seemed more affected by maturity although it is usually thought to be a sex-specific pattern. The third component, upper-lower body patterning, was more sexually dimorphic in adults. Marked differences were not observed between the two communities but over a 15-year period fatness levels increased slightly and subcutaneous fat tended to be deposited more centrally.     

Medieval trabecular bone architecture: the influence of age, sex, and lifestyle

Osteoporosis has become a growing health concern in developed countries and an extensive area of research in skeletal biology. Despite numerous paleopathological studies of bone mass, few studies have measured bone quality in past populations. In order to examine age- and sex-related changes in one aspect of bone quality in the past, a study was made of trabecular bone architecture in a British medieval skeletal sample. X-ray images of 5-mm-thick coronal lumbar vertebral bone sections were taken from a total of 54 adult individuals divided into three age categories (18-29, 30-49, and 50+ years), and examined using image analysis to evaluate parameters related to trabecular bone structure and connectivity. Significant age-related changes in trabecular bone structure (trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular separation (Tb.Sp), and anisotropic ratio (Tb.An)) were observed to occur primarily by middle age with significant differences between the youngest and two older age groups. Neither sex showed continuing change in trabecular structure between the middle and old age groups. Age-related changes in bone connectivity (number of nodes (N.Nd) and node-to-node strut length (Nd.Nd)) similarly indicated a change in bone connectivity only between the youngest and two older age groups. However, females showed no statistical differences among the age groups in bone connectivity. These patterns of trabecular bone loss and fragility contrast with those generally found in modern populations that typically report continuing loss of bone structure and connectivity between middle and old age, and suggest greater loss in females. The patterns of bone loss in the archaeological samples must be interpreted cautiously. We speculate that while nutritional factors may have initiated some bone loss in both sexes, physical activity could have conserved bone architecture in old age in both sexes, and reproductive factors such as high parity and extended periods of lactation could have played a key role in female bone maintenance in this historic population. The study of qualitative elements (such as trabecular architecture) is vital if we are to understand bone maintenance and fragility in the past.     

Age, growth and reproductive parameters of the Mediterranean cardinal fish, Apogon imberbis

Life history parameters (age, growth and reproductive characteristics) of the Mediterranean paternal mouthbrooding cardinal fish, Apogon imberbis, were investigated at a coastal locality off Blanes, NW Mediterranean Sea. Maximum age was found to be 5 years for both sexes. Age was validated with an otolith chemical (tetracycline) marking experiment. Both females and males reached maturity at length >5.5 cm, corresponding to 1 year of age in both sexes. The spawning season ranges from July to October, with a peak in August. The number of eggs in the mouths of males increased linearly with fish total length.     

黄山九龙峰保护区尖头的年龄、生长和繁殖

于2011年5月至2012年4月逐月采集标本, 对黄山九龙峰保护区尖头 (Phoxinus oxycephalus)的年龄、生长和繁殖等生活史特征进行了研究. 尖头 雌、雄鱼性比为0.77:1, 与1:1差异显著. 根据体长频率分布来确定年龄组成,结果显示雌鱼和雄鱼的最大寿命分别为3龄和2龄, 均以1龄和2龄为优势年龄组. 1龄时的体长生长速度最大, 至2龄或3龄逐渐变缓. 雌、雄鱼的初次性成熟年龄均为2龄, 对应体长分别为93.0 mm和76.9 mm. 尖头 繁殖时间为4-7月; 绝对繁殖力较低(174-2151卵粒), 且在2、3年龄组间显著差异, 但相对繁殖力无显著的年龄组间差异. 尖头 的上述生活史特征, 可能体现了对局域环境条件(如营养贫乏、环境动荡及水文周期等)的生态适应性. 尖头 在我国东南部的高海拔地区呈零星分布, 种群数量小, 加之繁殖投入低下, 因此该物种在面临人类干扰和环境变化时极易濒危和灭绝.       

A skeletochronological study of age, growth and longevity in a population of the frog Rana ridibunda from southern Europe

Age at sexual maturity and longevity in a population of Rana ridibunda from north-eastern Greece were studied by skeletochronology performed on the phalanges. Analysis of the age structure was based on counting the lines of arrested growth (LAGs). Sexual maturity for both sexes arises during the first year or after the first hibernation. Ages ranged from 1 to 5 years (mean=2.96) among 52 males and from 1 to 5 years (mean=3.73) among 56 females. The mean snout-vent length was 69.03+/-12.6mm in males and 82.38+/-13.27 mm in females. The difference between the sexes in age and size was significant. Growth of individuals was fitted on? The von Bertalanffy model. The growth coefficient (K) was 0.57 in males and 0.54 in females, mainly due to faster male growth between metamorphosis and maturation.     

Growth and skeletal maturation in British Columbia Indian Populations

Stature and skeletal maturation in childhood, mature stature, and calorie and protein intakes were studied in two populations of British Columbia Indians. Although mature stature was similar in both groups, one population (Anaham) showed delayed stature achieved for age and delayed skeletal maturity in childhood, compared with the other population (Ahousat). Analysis of growth data suggests that environmental factors are probably the predominant cause of the differences, which coincide with differences in nutritional status. Mean calorie intakes at Ahousat approximate or exceed the Canadian Dietary Standards, but those at Anaham are consistently below the standards for all age groups. Although mean protein intakes are well above the standards for all age groups, except teen-age girls at both reserves, they are consistently lower at Anaham than at Ahousat.     

Estimation of age at death from second metacarpals.

This study examined the estimation of age at death from the second metacarpal in 227 individuals aged 30-98 years. Variables ascertained from each bone were: cortical thickness and microdensitometric cortical bone density measured on radiographs of the bone and total osteon count and density recorded on microradiographs of the complete cross section at its midshaft. Based on the latter two variables, two age groups were formed; a middle age group representing those individuals aged 30-65 years, and an older group aged 65+. Stepwise regression analysis of the four variables produced a series of regression equations for age estimation for the middle, old and combined age groups for each sex and sexes combined. Sex-specific equations provided better results than nonspecific ones, especially in females. Total osteon density and combined cortical thickness were found to be the most useful estimators in the middle and the old age group, respectively. The standard error of estimate was 6.71 and 6.90 years in each age group for the sexes combined. In the combined age group, age could be estimated accurately from total osteon count, cortical thickness and MD cortical bone density with the standard error of estimate of 11.10 years. The relative error of estimate ranged within +/- 30% in almost all individuals aged above 60 years.     

Seasonal gonadal development and age-related maturity patterns of introduced pumpkinseed (Lepomis gibbosus Linnaeus, 1758) in a heated thermal reservoir and an adjacent river reach

Testis and ovarian maturation status, maturity profile and gonado-somatic index (GSI) were assessed in pumpkinseed (Lepomis gibbosus) collected from Mirgenbach, a cooling-water reservoir associated with a nuclear power plant, and from the River Moselle 7 km downstream of the reservoir's thermal outflow. Histological investigation indicated that in both sexes, gonadal development of pumpkinseed in the heated reservoir was more advanced than in the cooler Moselle River throughout the breeding season. The histological maturity profile of reservoir males ranked by the advancement of sperm cells was highly correlated with its GSI (r_s=0.73, P<0.001). GSI of females in the reservoir increased with the stage at maturity, but GSI was not significantly correlated with total length, age or growth rate of the individual. All sampled individuals of both sexes were mature at age 1 in the heated reservoir, whereas 48% of age 1 males and 57% of age 1 females were not mature in the river. GSI patterns suggest that males in the reservoir adopted one of two reproductive strategies (nesters or cuckolders), whereas no small males with large enough testes to be considered cuckolders were apparent in the river. The warm thermal regime of Mirgenbach Reservoir led to precocial maturity, early season reproduction, and the greater prevalence of apparent cuckolder males than would normally occur in this climatic zone.     

Sexual bimaturation and sexual size dimorphism in animals with asymptotic growth after maturity

Many animal taxa exhibit a positive correlation between sexual size dimorphism and sex differences in age at maturity, such that members of the larger sex mature at older ages than members of the smaller sex. Previous workers have suggested that sexual bimaturation is a product of sex differences in growth trajectories, but to date no one has tested this hypothesis. The current study uses growth-based models to study relationships between sexual size dimorphism and sexual bimaturation in species with asymptotic growth after maturity. These models show that sex differences in asymptotic size would produce sexual bimaturation even if both sexes approach their respective asymptotic sizes at the same age, mature at the same proportion of asymptotic size and have otherwise equivalent growth and maturation patterns. Furthermore, our analyses show that there are three ways to reduce sexual bimaturation in sexually size-dimorphic species: (1) higher characteristic growth rates for members of the larger sex, (2) larger size at birth, hatching or metamorphosis for members of the larger sex or (3) smaller ratio of size at maturity to asymptotic size (relative size at maturity) for members of the larger sex. Of these three options, sex differences in relative size at maturity are most common in size-dimorphic species and, in both male-larger and female-larger species, members of the larger sex frequently mature at a smaller proportion of their asymptotic size than do members of the smaller sex. Information about the growth and maturation patterns of a taxon can be used to determine relationships between sexual size dimorphism and sexual bimaturation for the members of that taxon. This process is illustrated for Anolis lizards, a genus in which both sexes exhibit the same strong correlation (r 0.97) between size at maturity and asymptotic size, and in which the relative size at maturity is inversely related to asymptotic size for both sexes. As a result, sexually size-dimorphic species of anoles exhibit the expected pattern of a smaller relative size at maturity for members of the larger sex. However, for species in this genus, sex differences in the relative size at maturity are not strong enough to produce the same age at maturity for both sexes in sexually size-dimorphic species. Members of the larger sex (usually males) are still expected to mature at older ages than members of the smaller sex in Anolis lizards.     

Reproductive cycle,sexual maturity and longevity of Odontophrynus americanus (Anura: Odontophrynidae) in South Brazil

Studies on the reproductive biology and age of amphibians provide primary information about the life history and population demographic parameters of species. Here, we describe the reproductive cycle, size–fecundity relationships, reproductive effort, sexual dimorphism and sexual maturity of Odontophrynus americanus, the flood frog, from South Brazil. A total of 96 individuals were analysed. The reproductive cycles of males and females were described through morphoanatomical analysis of testis and ovary. Age at onset of sexual maturity and estimated longevity were determined by skeletochronology. Individuals of O. americanus presented a potentially continuous reproductive cycle with a peak of reproductive activity in the warmer months. Females presented a higher reproductive investment than males. Sexual maturity was reached at around one year of age for both sexes while longevity differed between the sexes, with females living up to six years and males up to ten years. No evidence of sexual size dimorphism was found. This study is among the few that have assessed age at sexual maturity and longevity in a Neotropical anuran. Basic aspects of life history are of paramount importance because they allow comparisons and test of hypotheses to be made, which can help to build generalizations about the evolutionary meaning of ecological strategies.     

Life-history traits of the endangered river blenny Salaria fluviatilis (Asso) and their implications for conservation

The life-history characteristics of the river blenny Salaria fluviatilis in a Mediterranean stream in north-east Spain have been studied. The maximum age observed was 4+ years in both sexes, although only age groups 0+ and 1+ years were well represented. For both sexes, growth was rapid between April and June (before the summer drought) and in October. The instantaneous rate of monthly growth (April to October) was positively correlated with water depth. All fish attained sexual maturity during their first year of life. Females spawned multiple times. Spawning occurred mainly from June to August, although older females (2+ years old) began in May. The relationship between fecundity and total length recorded for older females in the spring was not significantly different from that obtained for 1 year-old females in the summer. The mean diameter of ripe oocytes, however, was greater in older females. Larger eggs that were laid during a period of good food supply (spring) might have a higher probability of survival. The results suggest that female fecundity is affected by environmental conditions. The species is characterized by fast growth, early maturity, multiple spawning and limited longevity. This may be a good life-history strategy for small fish species in unstable environments, where adult mortality is high, variable or unpredictable. Some life-history traits of the river blenny suggest that this species might be vulnerable to more severe drought conditions than those associated with the Mediterranean climate.     

Age estimation from cortical index of the human clavicle in northwest Indians

The proportion of the cortical thickness to the total diameter of the bone (cortical index) was calculated in paired clavicles obtained from 128 male and 82 female medicolegal postmortem subjects who were apparently healthy prior to their accidental death. The ages of the subjects varied from 15 to 85 years. The clavicles were cut either horizontally or parasagittally, and measurements were taken at midclavicle. From the ages of 15 to 30 years, the cortical index increased. It decreased steadily thereafter, with an initial sharp decrease in the age group 31-40 years in both sexes. After the age of 40 years, this rapid decrease in the index continued in the females, but became slow and gradual in the males. Differences between left and right sides were statistically insignificant in both sexes (P greater than 0.05). However, the sexual differences were significant (P less than 0.01) in the age groups from 41 years onwards.