Metatarsal fusion pattern and developmental morphology of the Olduvai Hominid 8 foot: Evidence of adolescence

The morphology of the Olduvai Hominid (OH) 8 foot and the sequence of metatarsal epiphyseal fusion in modern humans and chimpanzees support the hypothesis that OH 8 belonged to an individual of approximately the same relative age as the OH 7 subadult, the holotype of Homo habilis. Modern humans and chimpanzees exhibit a variety of metatarsal epiphyseal fusion patterns, including one identical to that observed in OH 8 in which metatarsal 1 fuses before metatarsals 2-5. More than the metatarsal fusion sequence, however, the principal evidence of the youthful age of OH 8 lies in the morphology of metatarsals 1, 2, and 3. Because both OH 8 and OH 7 come from the same stratum at the FLK NN type site, the most parsimonious explanation of the OH 8 and OH 7 data is that this material belonged to the same individual, as originally proposed by Louis Leakey. The proposition that OH 8 belonged to an adult is unsupported by morphology, including radiographic evidence, and the fusion sequences in human and chimpanzee skeletal material reported here and in the literature.     

Olduvai Hominin 8 foot pathology: A comparative study attempting a differential diagnosis

Olduvai Hominin (OH) 8, a 1.76 million year old left foot skeleton, has osteophytic lipping on the metatarsal bases, which when compared to a modern sample, may help paleoanthropologists determine whether the foot bones represent an injured subadult or an osteoarthritic adult. This study compares the OH 8 lipping pattern to those of 140 individual Amerindians comprising four different age classes to determine whether the OH 8 lipping is likely to be age-related osteoarthritis. OH 8 metatarsal lipping followed a pattern similar to that determined in the comparative sample to be age-related osteoarthritis. Similarities include metatarsal base lipping that is frequently located on the dorsal surface, metatarsal base lipping that is more severe on the lateral metatarsals compared to the medial metatarsals, and the presence of a pseudojoint between metatarsal 1 and metatarsal 2. The chance of finding an individual with osteoarthritis lipping increases from 3.45% in the age group 18–22 years to 55% in individuals over 35 years. The chance of finding a pseudojoint increases from 1.32% in non-osteoarthritic individuals to 15.15% in individuals with osteoarthritis. Results from this study indicate that the OH 8 foot bones are most likely from an adult and more likely to belong to Paranthropus boisei, the skull of which was found in the same excavations with OH 8, than to the juvenile Homo habilis holotype.     

The effect of dynamic loading on the growth of epiphyseal cartilage in the rat

The Hueter-Volkmann law of epiphyseal pressures describes an inverse relationship between static compressive forces parallel to the axis of epiphyseal growth and the rate of growth of that cartilage. Studies of histological sections of the epiphyseal plate of the fourth metatarsals of (a) control, (b) bipedal and (c) bipedal rats with amputation of the fifth metatarsal show that dynamic compressive forces can stimulate epiphyseal cartilage growth. Within certain parameters, both the relief and increase of dynamic compression accelerate epiphyseal growth. It is the amount and kind of loading that are important factors to accelerate epiphyseal growth.     

Group Choice by Subadult Bighorn Rams: Trade-offs between Foraging Efficiency and Predator Avoidance

In addition to sexual segregation, many social ungulates show varying degrees of age segregation, especially among males. We investigated factors affecting group choice by subadult male bighorn sheep, using census data collected between 1982 and 1998 in a marked population. We examined whether group composition varied with population size and structure. Changes in total population size were correlated with the number of yearling males and yearling females, but not with the size of other sex-age classes. In years of high population size, female groups were larger than in years of low population size, while mixed sex-age and subadult groups showed a nonsignificant trend in the same direction. Typical group sizes of bachelor groups and the occurrence of mixed or bachelor groups were not affected by population size. When there were few subadult males in the population, groups of subadult males were less frequent than in years with many subadult males in the population, but the typical group size did not change. Subadult males were rarely seen in peer groups, and switched from female groups in spring to bachelor groups in autumn. An individual's choice of group type is affected by its body mass, but also by the availability of enough potential group mates to provide sufficient predator-detection efficiency.     

Features of development of fetal bone organ culture in space flight

Fetal mouse metatarsals cultured for 4 days onboard international space laboratory IML-1 (STS-42) were investigated using light microscopy and electron microscopy combined with X-ray microanalysis. Bones cultured in microgravity were equal in length to both ground and inflight (1 g) controls. Three zones: epiphyseal, proliferative, and hypertrophic chondrocytes were distinguished and measured in metatarsals isolated from 16-day-old fetuses. In bone cultures exposed to microgravity, hypertrophic zone tended to decrease and epiphyseal area was increased compared to controls. Proliferative zone has equal length both in bones cultured under microgravity and in controls. The same tendency was observed in bone cultures from 17-day-old fetuses. Metatarsals cultured in microgravity have less spreading calcification zone of diaphysis in comparison with both controls. The results suggest that maturation of chondrocytes and calcification of cartilage, but not cell proliferation, are microgravity sensitive processes in developing bones isolated from the organism.     

The Olduvai Hominid 8 foot: Adult or subadult?

Olduvai Hominid 8 (OH 8), an articulating set of fossil hominin tarsal and metatarsal bones, is critical to interpretations of the evolution of hominin pedal morphology and bipedal locomotion. It has been suggested that OH 8 may represent the foot of a subadult and may be associated with the OH 7 mandible, the type specimen of Homo habilis. This assertion is based on the presence of what may be unfused distal metatarsal epiphyses. Accurately assessing the skeletal maturity of the OH 8 foot is important for interpretations of the functional morphology and locomotor behavior of Plio-Pleistocene hominins. In this study, we compare metatarsal fusion patterns and internal bone morphology of the lateral metatarsals among subadult hominines (85 modern humans, 48 Pan, and 25 Gorilla) to assess the likelihood that OH 8 belonged to either an adult or subadult hominin. Our results suggest that if OH 8 is indeed from a subadult, then it displays a metatarsal developmental pattern that is unobserved in our comparative sample. In OH 8, the fully fused base of the first metatarsal and the presence of trabecular bone at the distal ends of the second and third metatarsal shafts make it highly improbable that it belonged to a subadult, let alone a subadult that matches the developmental age of the OH 7 mandible. In total, the results of this study suggest that the OH 8 foot most likely belonged to an adult hominin.     

Adoption of an additional infant by a Western lowland gorilla (Gorilla gorilla gorilla).

A 10-year-old Western lowland gorilla, already caring for her own 14-month-old son, adopted a female neonate. The infant's mother (aged 7 years, 4 months) showed no interest in the infant, and it is unclear whether she abandoned the infant or whether it was seized by the dominant foster-mother. The foster-mother gave more maternal attention to the adoptee than to her own son but gave both infants the same protection. She adjusted her forms of transport to the age of each infant. The subadult mother of the neonate did not seek contact with her offspring during the first 4 weeks and in fact showed more interest in the 14-month-old male infant. Interactions between the two mothers were rare. The foster-mother's own male infant died 2 months after she had adopted the female infant. She looked after the adopted infant for 1 year, but then lost interest so that the adoptee had to be separated.     

Morphological variation of introduced species: The case of American mink (Neovison vison) in Spain

We studied the morphology of American mink Neovison vison in five out of the six introduced populations in Spain. The spatial and temporal variation of body weight (BW), body length (BL), tail length, hind-foot length and ear length were analysed. Temporal trends in BW and BL in relation to years since mink introduction were also analyzed. In addition, we tested the effect of sex, age (juvenile, subadult and adult) and age–sex interaction, on each parameter. Morphological parameters differed between populations, illustrating the high variability of body size of American mink in different environments, and the phenotypic plasticity of the species. Annual variations were synchronized between populations, suggesting a large-scale effect on all of them. BW and BL showed a decreasing trend in both males and females in relation to years since introduction. This decrease may be related to mink's diet. Differences in sex and age were found, pointing to sexual dimorphism in adults, subadults and juveniles. The dimorphism in non-adult individuals suggests that subadult males may have a competitive advantage from subadult females in feeding and/or hunting on bigger prey from an early age (resource partitioning hypothesis).     

Epiphyseal union at the innominate and lower limb in a modern Portuguese skeletal sample, and age estimation in adolescent and young adult male and female skeletons

This study documents the timing of epiphyseal union at the innominate, femur, tibia, and fibula in a sample of modern Portuguese skeletons. The sample was taken from the Lisbon documented skeletal collection and it is comprised of 57 females and 49 males between the ages of 9 and 25. Individuals are mostly representative of the middle-to-low socioeconomic segment of the early 20th century Lisbon population. A total of 18 anatomical locations were examined for epiphyseal union using a three-stage scheme: 1) no union; 2) partial union; and 3) completed union, all traces of fusion having disappeared. Results show that females are ahead of males by 1-2 years and provide similar age ranges for the stages of union than previous studies. Some variations between studies can be explained by methodological differences between dry bone and radiographic observations. However, a review of the literature indicates that socioeconomic status of a given population seems to be of decisive importance to the rate of ossification and most of the differences in skeletal maturation across studies and populations can probably be ascribed to different levels of social and economic development of the societies in which the individuals lived. Although the effects of socioeconomic status in skeletal maturation are greater during childhood than in adolescence, as to make the timing of epiphyseal union a reliable estimate of age at death, they are not negligible and age estimates should take into account the likely socioeconomic status of the individual, whose remains are under examination.     

Patterns in ontogeny of human trabecular bone from SunWatch Village in the Prehistoric Ohio Valley: general features of microarchitectural change

Although adult skeletal morphological variation is best understood within the framework of age-related processes, relatively little research has been directed towards the structure of and variation in trabecular bone during ontogeny. We report here new quantitative and structural data on trabecular bone microarchitecture in the proximal tibia during growth and development, as demonstrated in a subadult archaeological skeletal sample from the Late Prehistoric Ohio Valley. These data characterize the temporal sequence and variation in trabecular bone structure and structural parameters during ontogeny as related to the acquisition of normal functional activities and changing body mass. The skeletal sample from the Fort Ancient Period site of SunWatch Village is composed of 33 subadult and three young adult proximal tibiae. Nondestructive microCT scanning of the proximal metaphyseal and epiphyseal tibia captures the microarchitectural trabecular structure, allowing quantitative structural analyses measuring bone volume fraction, degree of anisotropy, trabecular thickness, and trabecular number. The microCT resolution effects on structural parameters were analyzed. Bone volume fraction and degree of anisotropy are highest at birth, decreasing to low values at 1 year of age, and then gradually increasing to the adult range around 6-8 years of age. Trabecular number is highest at birth and lowest at skeletal maturity; trabecular thickness is lowest at birth and highest at skeletal maturity. The results of this study highlight the dynamic sequential relationships between growth/development, general functional activities, and trabecular distribution and architecture, providing a reference for comparative studies.     

Using multivariate adaptive regression splines to estimate subadult age from diaphyseal dimensions

Subadult age estimation is considered the most accurate parameter estimated in a subadult biological profile, even though the methods are deficient and the samples from which they are based are inappropriate. The current study addresses the problems that plague subadult age estimation and creates age estimation models from diaphyseal dimensions of modern children. The sample included 1,310 males and females between the ages of birth and 12 years. Eighteen diaphyseal length and breadth measurements were obtained from Lodox Statscan radiographic images generated at two institutions in Cape Town, South Africa, between 2007 and 2012. Univariate and multivariate age estimation models were created using multivariate adaptive regression splines. k‐fold cross‐validated 95% prediction intervals (PIs) were created for each model, and the precision of each model was assessed. The diaphyseal length models generated the narrowest PIs (2 months to 6 years) for all univariate models. The majority of multivariate models had PIs that ranged from 3 months to 5 and 6 years. Mean bias approximated 0 for each model, but most models lost precision after 10 years of age. Univariate diaphyseal length models are recommended for younger children, whereas multivariate models are recommended for older children where the inclusion of more variables minimized the size of the PIs. If diaphyseal lengths are not available, multivariate breadth models are recommended. The present study provides applicable age estimation formulae and explores the advantages and disadvantages of different subadult age estimation models using diaphyseal dimensions. Am J Phys Anthropol 154:376–386, 2014. © 2014 Wiley Periodicals, Inc.     

Diagnostic scintigraphy and effectiveness of 131I radioiodine therapy in differentiated thyroid carcinoma (DTC)

INTRODUCTION: Since the effect of pre-therapeutic scintigraphy on the outcome of DTC treatment is debated, we evaluated factors affecting the effectiveness of (131)I therapy with respect to the delay between diagnostic scintigraphy and the application of radioiodine. MATERIAL AND METHODS: In the studied group of 60 patients with DTC, mean age 54.6 +/- 13.0 years, four weeks prior to the planned diagnostics, L-thyroxine was withdrawn and the following tests performed: (131)I (4 MBq) uptake above the neck, thyroid volume by USG, TSH and hTg level. Wholebody scintigraphy (37 MBq) was performed. The time between this diagnostic scintigraphy and application of (131)I (3657 MBq) was calculated. Based on whole-body 131I scintigraphy (74 MBq) performed 1 year after radioiodine treatment, the patients were divided into: group I - 42 patients with no tracer accumulation, and group II--18 patients who continued to accumulate (131)I in the neck. RESULTS: The differences between the median values of (131)I uptake and of thyroid volumes, and between the TSH and hTg median values in the two groups of patients were found not to be statistically significant. The average times between diagnostic scintigraphy and (131)I treatment in group I and II (9.4 vs. 8.3 weeks, respectively) were not significantly different either. CONCLUSION: Despite the different effectiveness of supplementary (131)I treatment, patients in group I and group II showed no statistically significant differences in the studied parameters. It appears that the diagnostic (131)I activity of 37 MBq and the time between diagnostic scintigraphy and application of (131)I did not have any effect on the results of the treatment in our group of patients.     

Age estimation from stages of epiphyseal union in the presacral vertebrae

The presacral vertebrae have various secondary centers of ossification, whose timing of fusion can be used for age estimation of human skeletal remains up to the middle to the latter third decade. However, detailed information about the age at which these secondary centers of ossification fuse has been lacking. In this study, the timing of epiphyseal union in presacral vertebrae was studied in a sample of modern Portuguese skeletons (57 females and 47 males) between the ages of 9 and 30, taken from the Lisbon documented skeletal collection. A detailed photographic record of these epiphyses and the age ranges for the different stages of epiphyseal union are provided. Partial union of epiphyses was observed from 11 to 27 years of age. In general, centers of ossification begin to fuse first in the cervical and lumbar vertebrae, followed by centers of ossification in the thoracic region. The first center of ossification to complete fusion is usually that of the mammillary process in lumbar vertebrae. This is usually followed by that of the transverse process, spinous transverse process, and annular ring, regardless of vertebra type. There were no statistically significant sex differences in timing of fusion, but there was a trend toward early maturation in females for some vertebra or epiphyses. Bilateral epiphyses did not show statistically significant differences in timing of fusion. This study offers information on timing of fusion of diverse epiphyseal locations useful for age estimation of complete or fragmented human skeletal remains. Am J Phys Anthropol, 2011. © 2010 Wiley‐Liss, Inc.     

Population variables and causes of mortality in a hedgehog (Erinaceous europaeus) population in southern Sweden

A hedgehog population in southern Sweden was studied by capture-mark-recapture during 1972–1979. Each animal was weighed, sexed and marked with one numbered clip in each ear.
The number of subadult and adult hedgehogs was about 20 in the first two years, 1972–1973. Numbers then increased and approximately doubled and the population peaked in 1978. A decrease came in 1979.
The estimated number of juveniles produced varied between years with the lowest figure (15 juv.) in 1974 when the population was low and the highest in 1977 (39 juv.) when the population was high. As no captured subadult female had suckled young, estimates of recruitment rate assumed that females did not reproduce until they were adult. The average number of juveniles per adult female was 2.8. Recruitment rate did not show any correlation with non-juvenile population densities.
For both juveniles and non-juveniles the annual mortality varied greatly between years. Average yearly mortality was 47% for non-juveniles and 34% for juveniles.
For non-juveniles, most of the total mortality occurred during winter, ranging between 26% and 43% (average 33%), and increased with increasing densities of non juveniles. Juvenile winter mortality varied between 6% and 94%, averaging 33%.
Summer mortality of non-juveniles averaged 15%, ranging between 3% and 22%. Traffic kills were the predominant cause of death. Only a few juveniles were found dead during summer and autumn.
There were no statistical differences in age-specific survival rate between males and females and, generally, no differences in survival rate between the age categories within each sex. It is argued that the population size appears to be more influenced by environmental factors, such as food availability, winter nest sites and winter climate, than by density-dependent factors.     

Epiphyseal union of the anterior iliac crest and medial clavicle in a modern multiracial sample of American males and females

Epiphyseal union of the anterior iliac crest and the medial clavicle is examined in 605 males and 254 females in a sample of modern Americans aged 11-40 years. The sample includes American whites, American blacks, Latin-Americans, and Orientals. This is the first skeletal investigation using a large sample of individuals of known age since the McKern and Stewart study of 1957. Epiphyseal union is analyzed in terms of four stages: 1) nonunion with no epiphyses, 2) nonunion with separate epiphyses, 3) partial union, and 4) complete union. The results provide broader age ranges for the stages of union than previous studies. Age ranges for males and females are similar or vary by only 1-2 years. Racially, no major distinguishing patterns are found except for greater variability in age distributions appearing to exist among American black females. The study furnishes valuable data on epiphyseal timing in the teenage years.     

The meaning of weaning in wild Phayre's leaf monkeys: Last nipple contact,survival, and independence

In primates and other mammals, weaning is an equivocal concept, as is reflected in the numerous ways it is measured: a) first intake of solid food, b) conflict over access to the nipple, c) ability to survive without mother, d) maternal resumption of cycling, or e) the cessation of nipple contact. The lack of a consistent definition means that weaning age, although it falls between gestation (fetal growth) and age at first reproduction (most energy diverted from growth), is currently not a reliable life history variable capturing offspring independence. Using data for wild Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) at Phu Khieo Wildlife Sanctuary, Thailand (51 offspring, four groups), we asked whether the end of nipple contact indicates offspring independence as measured by survival to 3 years. To establish a baseline for the onset of independence, we assessed the youngest age at which individuals were orphaned (15–17 months) but then survived to 3 years. Next we determined that offspring age at last nipple contact (19.0 months) was comparable to two other independently calculated measures: offspring age at mother's first postpartum ovulation (11.5 months), and age at mother's re‐conception (15.6 months). Using these separate “starting points,” we arrived at similar ages for nipple contact cessation (18.4 and 19.2 months, respectively). Overall, in wild (but not in provisioned) Asian colobines, age at last nipple contact was allometrically related to adult female body mass, supporting its designation as a life history variable. Future comparisons need to show if this holds for other taxa. Am J Phys Anthropol 154:291–301, 2014. © 2014 Wiley Periodicals, Inc.     

Male-infant relationships in semifree-ranging Barbary macaques (Macaca sylvanus) of affenberg salem/FRG: Testing the “male care” hypothesis

The infant-directed behavior of Barbary macaque males was analyzed in order to determine whether it is essential for an infant's survival during the first year and whether males interact selectively with closely related infants. Dyadic male-infant contacts were recorded in a large group of semifree-ranging Barbary macaques. Data collected during the first 12 weeks of life on each infant born in 1983 (n = 36) were analyzed. All adult and almost all subadult males established strong relationships with at least one infant. Almost two-thirds of the infants (22) had frequent contacts with one or several males. Males showed no preference for closely related infants. Sexual associations with an infant's mother during the preceding mating season had no significant effect. Natal males did not prefer infants of their own matrilineage. There was no evidence that contacts with males had a positive influence on infant survival or that other benefits to the infants resulted from these contacts. Instead, excessive carrying by males and females led to starvation of some very young infants and was a major cause of neonatal deaths in this population. Males interacted preferentially with infants that were born early in the birth season, had a high-ranking multiparous mother, and were male. Younger males established strong relationships with male infants only, while mother's rank was more important for older males. It is suggested that certain mothers prevented early contacts between their infants and males so that the observed preferences for certain infants were also a result of easier access to them. All results suggested that males interacted with infants for their own benefit.     

Age of epiphyseal closure in tamarins and marmosets

Estimates of the chronological age for animals of unknown age provide useful information for medical, demographic, and evolutionary studies. Skeletal development, as indicated by epiphyseal closure, can be used to estimate an animal's chronological age or specify its stage of development. Many studies of Primate skeletal development have used animals of unknown age, with the order of epiphyseal closure providing a relative age for each animal. This study examines the age of epiphyseal closure at 22 epiphyseal sites using animals of known age at death in three calitrichid species (Saguinus fuscicollis, Saguinus oedipus, and Callithrix jacchus). The observed average age of epiphyseal closure is similar in these tamarins and marmosets. There is a significant difference in rate of development between the species. Regression equations can predict the age of unknown animals to within 4.8 months for S. fuscicollis, 8.6 months for S. oedipus, and 7.6 months for C. jacchus (twice the standard error of the estimate). These age estimates allow us to determine if an animal is relatively mature or immature, but are largely unacceptable for studies in which precise age estimates are necessary. The order of epiphyseal closure is similar across 11 monkey species (using additional data from published literature) and supports the suggestion of a general pattern in Primate skeletal development. Am. J. Primatol. 41:129–139, 1997. © 1997 Wiley-Liss, Inc.     

Brief communication: A probabilistic approach to age estimation from infracranial sequences of maturation

Infracranial sequences of maturation are commonly used to estimate the age at death of nonadult specimens found in archaeological, paleoanthropological, or forensic contexts. Typically, an age assessment is made by comparing the degree of long‐bone epiphyseal fusion in the target specimen to the age ranges for different stages of fusion in a reference skeletal collection. While useful as a first approximation, this approach has a number of shortcomings, including the potential for “age mimicry,” being highly dependent on the sample size of the reference sample and outliers, not using the entire fusion distribution, and lacking a straightforward quantitative way of combining age estimates from multiple sites of fusion. Here we present an alternative probabilistic approach based on data collected on 137 individuals, ranging in age from 7‐ to 29‐years old, from a documented skeletal collection from Coimbra, Portugal. We then use cross validation to evaluate the accuracy of age estimation from epiphyseal fusion. While point estimates of age can, at least in some circumstances, be both accurate and precise based on the entire skeleton, or many sites of fusion, there will often be substantial error in these estimates when they derive from one or only a few sites. Because a probabilistic approach to age estimation from epiphyseal fusion is computationally intensive, we make available a series of spreadsheets or computer programs that implement the approach presented here. Am J Phys Anthropol 142:655–664, 2010. © 2010 Wiley‐Liss, Inc.     

日本梅花鹿与大丰麇鹿发情期反刍行为的差异

家养有蹄类动物的反刍行为已有大量研究,而受限于野外条件,野生有蹄类动物反刍行为的研究有限。以往研究认为,体型可能是影响动物反刍行为的重要因素。本研究以日本奈良公园日本梅花鹿Cervus nippon nippon和中国江苏大丰麋鹿Elaphurus davidianus为研究对象,观察记录并比较分析了发情期的日本梅花鹿与发情期的麋鹿在卧息时反刍行为的种内及种间差异。按照年龄性别差异,分5种类型(成年雄性、成年雌性、亚成雄性、亚成雌性和幼鹿)研究两物种食团咀嚼时间、咀嚼频率和咀嚼速率的差异。结果表明,1)日本梅花鹿的咀嚼速率和食团咀嚼时间受性别-年龄的显著影响:咀嚼速率为幼体>亚成雌性>亚成雄性>成年雌性>成年雄性,而食团咀嚼时间为成年雄性>亚成雄性>成年雌性>亚成雌性>幼体;2)性别-年龄对麋鹿咀嚼频率有显著的影响,成年雄性<成年雌性<亚成雄性<亚成雌性<幼体;3)两物种在咀嚼频率、食团咀嚼时间和咀嚼速率上的差异均有统计学意义,体型更大的麋鹿咀嚼速率更慢,食团咀嚼时间更长。与体型相关的性别及年龄显著影响了日本梅花鹿和麋鹿的反刍行为。