桂林甑皮岩新石器时代遗址2例儿童的年龄问题

作者报告２例于桂林甑皮岩新石器时代早期遗址出土的正处于换牙期的儿童乳、恒牙更换及其被磨耗的状况,讨论了从他们的牙磨耗级估计的年龄与从其乳、恒牙更换关系估计的年龄的误差,并提出用现代人牙磨耗级估计史前人类年龄的意见．     

Age estimation of the White rhinoceros (Ceratotherium simum)

Age estimation criteria for the southern White rhinoceros ( Ceratotherium simum simum ) are presented both for free-ranging live animals and for cranial material. These are based on: (i) size appearance and horn development of live animals; (ii) stages of tooth eruption; (iii) tooth wear classes; (iv) attrition in height of the first molar tooth; (v) counts of cementum lines visible in tooth sections. Selected measurements are presented for live animals, skulls and horns.
For live animals, eight size classes are distinguished, seven of these covering immature animals up to ten years of age. Sixteen tooth wear classes are established, based on eruption and surface wear of maxillary dentition. Chronological ages were assigned from individually known animals followed in the field, and from skulls from animals for which exact records of age were available, or which could be assigned to an age category from appearance at death. Cementum line counts corresponded approximately with age in years, despite difficulties in interpreting lines. Some variability was observed, possibly related to nutritional conditions.
The maximum cementum line count obtained indicates a longevity of at least 40 years. Full body weight and socio-sexual maturity are attained by males between 10 and 15 years of age, while females first give birth between six and eight years of age. Sequences and times of tooth eruption are similar to those reported for the Black rhinoceros ( Diceros bicornis ).
Comparative cranial and body measurements are presented for the northern subspecies ( Ceratotherium simum cottoni ).     

Field age determination of leopards by tooth wear

Age determination is an important tool in wildlife studies. Estimating the age of animals in the field using tooth wear criteria may be subject to error as a result of variations between individuals, habitats and populations. Data on age estimation of leopards and tooth wear characteristics are lacking. Nineteen leopards in Namibia were assessed for tooth eruption and wear. Between 1991 and 1995 leopards (including 13 individuals of known age) were monitored at one year intervals ('28 leopard years') to record age and tooth wear. At the age of two years leopards had fully developed dentition. Wear started with the incisors and canines, and spread to the premolars and molars. A chronology of tooth eruption and wear in relation to age is presented. Above the age of three years, male leopards showed higher frequencies of enamel flaking and canine fractures than females.     

THE AGEING OF IMPALA FROM A POPULATION IN THE KENYA RIFT VALLEY

Material from 100 impala from a mainly grazing population in the Kenya Rift Valley was investigated to establish age criteria applicable in both the field and the laboratory. Methods relate to tooth eruption, replacement and attrition; horn development; skull and long bone growth and ossification. Determinations are related to the main calving seasons, which occur with two peaks at the time of the long and short rains. All results are approximations which have an accuracy of ±2 months up to physical maturity at an age of c. 2 y. Age determination in animals from 3–8 y appears to yield reliable results with an accuracy of ±6 months at the lower end of the scale, and ± 1 y or even 2 y in older animals.     

Estimating age of immobilized elephants from teeth impressions using dental silicon

High precision condensation dental silicon, Zetalabor^TM, was used to create moulds of the lower jaw molars from 22 immobilized African elephants (Loxodonta africana Blumenback) during radio collaring operations. These moulds were used to determine the elephant's age using Laws and Jachmann's molar aging criteria. The technique proved easy and fast and produced useful imprints in 90% of the cases. We found our age estimates, based on physical appearance, made prior to immobilizations were relatively accurate, with 75% within ±3 years and 95% within ±5 years from the age indicated from molar evaluation. When re‐collaring the same individuals in 2–3 years, new moulds will be made to compare a known time period with the degree of tooth wear. This will provide verification of Laws age estimates from free‐ranging elephants.     

A tooth wear scoring scheme for age estimation of the Eurasian lynx (<Emphasis Type="Italic">Lynx lynx</Emphasis>) under field conditions

Within the framework of conservation actions for the Eurasian lynx (Lynx lynx), ageing of individuals is required to assess suitability for translocation and to investigate population dynamics and disease epidemiology. We aimed to develop a standardised ageing tool for free-ranging Eurasian lynx, which would be non-invasive, time- and cost-effective, and applicable under field conditions. We used tooth pictures of 140 free-ranging lynx of known age from Switzerland. Tooth colour, calculus, number of incisor teeth and canine, premolar and molar tooth wear were recorded according to pre-defined criteria. Statistical comparisons among the categories of each criterion revealed significant differences for all criteria. Tooth colour and canine tooth morphology showed obvious and consistent alterations with age. Together with the molar tooth shape, premolar tooth tips, incisor teeth and amount of calculus, they pictured the age-related changes in lynx dentition. Crown fractures, enamel flaking and open pulp cavities were observed with an increasing prevalence over age but were also sporadically seen in juveniles. Based on the obtained results, we developed a classification scheme distinguishing six age classes: <?1 year, 1–2 years, 3–6 years, 7–9 years, 10–13 years, ≥?14 years. The scheme was subsequently tested with the same lynx. Classification success rates of different readers ranged from 69 to 88% but errors did not exceed one age class. The homogenous tooth replacement pattern observed in lynx <?1 year allowed us to develop a separate ageing chart to age juveniles in months. The proposed scheme is a promising tool to objectively assign lynx to meaningful age categories.     

Age determination in roe deer — a new approach to tooth wear evaluated on known age in dividuals

A novel, simple, and objective method is presented for ageing roe deerCapreolus capreolus (Linnaeus, 1758) evaluated on 471 lower jaws from roe deer of known age (351 with permanent premolars). It is based on tooth eruption patterns and presence/absence of wear characters in jaws from roe deer integrated in a scoring system. Permanent cheek teeth emerge in May–July in the year af ter birth, which enables precise age determination of individuals with deciduous premolars. For individuals with permanent cheek teeth, the method provides the correct age for all individ uals younger than 13 months and > 80% of all individuals between 13 and 24 months old. For older in dividuals the accuracy decreases, but decent accuracy is achieved to the age of 48 months. Males have higher wear rates than females corroborating recent documentation of sex-specific life history tactics in ungulates. The data originate from two separated Danish roe deer populations exposed to contrasting habitats, but no difference in wear rate is found between populations. Thus, previous concern about the validity of age determination methods based on tooth wear may have been overstated. The findings demonstrate that objective measures of tooth wear can provide the basis for age determination in ungulate species that are otherwise difficult to age.     

Determination of age in Cantabrian chamois (Rupicapva pyvenaica pavva) from jaw tooth-row eruption and wear

A tooth eruption and wear pattern useful to determine ten age classes when the horns are not available for this purpose, is described for Cantabrian chamois ( Rupicapra pyrenaica parva ) inhabiting the Cantabrian Mountains (north of Spain). In animals under eight years old, age is not significantly over- or under-estimated when using the method, however, the age of animals older than eight years is significantly under-estimated.     

Dental Eruption Series and Replacement Pattern in Miocene <Emphasis Type="Italic">Prosantorhinus</Emphasis> (Rhinocerotidae) as Revealed by Macroscopy and X-ray: Implications for Ontogeny and Mortality Profile

Fossil evidence of complete sequences of dental ontogeny in extinct mammals is rare but contains valuable information on the animal’s physiology, life history, and individual age. Here, we analyzed an exceptionally high number of juvenile dentaries at different developmental stages including highly fragile tooth germs of the extinct rhinoceros Prosantorhinus germanicus from the Miocene fossil lagerstätte Sandelzhausen in Germany. We used dental wear stages, eruption stages, and tooth germ development in order to reconstruct the tooth replacement pattern for P. germanicus. The results allow for the distinction of 11 dental eruption stages and document a tooth eruption sequence of (d2, d3), (d1, d4), m1, m2, p2, p3, p4, m3; a pattern identical to that reported for the extant African rhinoceros, Diceros bicornis. Moreover, our findings indicate that P. germanicus falls into the life history category of slow-growing, long-living mammals. The dental eruption stages of the fossil rhinoceros were correlated with data of living rhinoceroses in order to gain insight into the age-at-death distribution of P. germanicus at Sandelzhausen. The juvenile mortality profile of P. germanicus shows a trend of selective mortality at an inferred age range of about 3 months to 3 years. As this age range represents a life phase of increased natural risk of mortality, our findings indicate a gradual accumulation of corpses (attritional fossil assemblage). This result supports the interpretation of a taphocenosis found at the Sandelzhausen fossil site.     

Dental emergence among urban Zambian school children: An assessment of the accuracy of three methods in assigning ages

In situations where birth records are unavailable and stated ages are unreliable, the emergence of the permanent dentition can serve as an indicator of age. Due to substantial variation in the timing of tooth emergence, a sample (n = 721) of Zambian school children, with known ages, was examined to provide a tooth emergence reference standard for the area. Three methods for assigning ages were utilized and their accuracy assessed. A random test sample was withheld from the original study in order to further evaluate the methods' accuracy. The three methods—1) number of teeth, 2) regression and 3) probit analysis—were applied to Zambian children, and estimates of age were made. Predicted ages were compared to actual ages to determine the percentage of accuracy in three categories—±.5, ±1.0 and ±2.0 years—and paired t-tests were conducted. Each of the three methods was then applied to the test sample, and their accuracy was evaluated in the same manner. Methods 1 and 2 were found to provide the higher percentage of correct ages within ±.5 years, assigning roughly 39% of both male and female children within this increment. This was also the case at the next increment, with methods 1 and 2 assigning a higher percentage (66–76%) of children to the ±1.0 year category, while the accuracy of method 3 was quite a bit lower. The results for the test sample were very similar to those of the main sample. The overall accuracy of methods 1 and 2 was very similar in both the main and test samples, while method 3 had lower accuracy and t-tests indicated significant differences. Therefore, due to ease of application in the field setting, method 1, mean age per number of teeth emerged, is the method of choice. Am J Phys Anthropol 102:447–454, 1997. © 1997 Wiley-Liss, Inc.     

Age determination and growth in the hyrax Procavia capensis (Mammalia: Procaviidae)

The use of eye lens weight, tooth eruption and tooth attrition has been investigated as a method for age determination in the hyrax. Illustrations are presented on the stages of eruption to reduce subjectivity of eruption criteria and to aid age determination. All teeth are fully erupted and in wear by five years of age, from which point age determination can be based on attrition of M3. Growth with age is described by means of the von Bertalanffy equation. Asymptotic weight is reached by 60 months, asymptotic body length and body girth by 40 months, and hindfoot length by 35 months. The asymptotes and the coefficient of catabolism (K) are compared with values obtained in other studies.     

The age of puberty of the hippopotamus (Hippopotamus amphibius Linn.) in the Luangwa River in eastern Zambia

As part of a study of the ecology of a high density hippopotamus population (Hippopotamus amphibius) in the Luangwa river in eastern Zambia, a shot sample of 176 males and 161 females was examined. All animals were classified according to age (0–43 years). The female reproductive organs were removed, dissected, examined, and the lactational status was noted. Ovaries and corpora Iutea were weighed, sliced, and all follicles > 5 mm in diameter were recorded. The testes of the males were dissected and weighed. Indications of puberty and maturity in the female were observed in some animals at an age of about 7 and 8 years respectively; but some animals were still not breeding until 20 years of age and the ages at which 50% of the female population reached puberty and maturity (Laws & Clough, 1966) were 11 and 13 years respectively. In the male, puberty begins at an average age of 6 years and maturity is reached at approximately 8 years of age. The data showed that lactation has no effect on ovarian weight or activity. The weight of the corpus luteum during pregnancy (36–72 ± 2–65 g) is significantly (P < 0–01) greater than that observed in non-pregnant animals (16–64 ± 2–46 g). Multiple ovulation occurs in 8–10% of the animals.     

The relative age structure and body masses of complete wild-captured colonies of two social mole-rats, the common mole-rat, Cryptomys hottentotus hottentotus and the Damaraland mole-rat, Cryptomys damarensis

The relative ages of individuals in a complete wild-captured colony of 13 Cryptomys hottentotus hottentotus and a complete wild-captured colony of 25 Cryptomys damarensis were determined by means of tooth wear and eruption patterns and through the degree of ossification of their skeletons.
From sequential tooth wear and eruption patterns four relative age classes were discerned in C. h. hottentotus and five in C. damarensis . These relative age class allocations were supported by the studies on the ossification of the skeletons.
In C. damarensis , older animals are not necessarily the larger-sized individuals. In C. h. hottentotus , however, older animals are usually the larger-sized individuals. The reproductive pair in each of the Cryptomys species are the oldest or amongst the oldest individuals in the colony.
Individuals in a second colony of C. damarensis kept under laboratory conditions for three years maintained greatly disparate body masses which were correlated with the role of the individual within the colony and not, where it was known, with the age of the animal.
An analysis of 13 body and skull measurements performed on a complete colony of 13 C. h. hottentotus and a complete colony of 25 C damarensis revealed that only C. damarensis showed sexual dimorphism. This dimorphism was apparent from an early age but became more pronounced in older animals.     

Direct effects of tephra fallout from the Puyehue–Cordón Caulle Volcanic Complex on Nothofagus pumilio ring widths in northern Patagonia

We evaluated the radial growth response of adult Nothofagus pumilio (Poepp. et Endl) Krasser trees affected by tephra deposition following historical volcanic eruptions of the Puyehue–Cordón Caulle Volcanic Complex (PCCVC) in northern Patagonia. Standard tree–ring width chronologies were developed for trees from two sites that were affected by up to 55 cm of tephra during the 2011 eruption, which allowed us to detect the general tree–growth response to eruptions VEI ≥ 3 and VEI ≤ 2. The tree growth trend satisfactorily followed the mean temperature record (r = 0.42); however, the analysis of studentized residuals identified outliers (≥ ± 2 SD) directly related to the volcanic eruptions of the years 1921–1922 and 2011 and the respective post–eruption years, while for the 1960 eruption and following year, they largely exceeded the mean value of the residuals. The large amount of tephra deposited during the 1921–22 and 2011 eruptions caused physical damage to the tree canopy leading to the appearance of white rings and to locally absent rings. The rate of change in radial growth of trees during these eruptions presented significant declines in relation to the growth of five years before the eruption and to the following year. The low amount of tephra deposited during the 1960 eruption did not cause damage to the stands and trees increased their radial growth. In general, trees that had reduced radial growth experienced a remarkable recovery starting in the second or third post–eruption year. The amount of tephra deposited and the time of year of the volcanic eruptions had an important influence on tree rings. Some ecophysiological causes that could explain the growth responses of N. pumilio to tephra fall are discussed herein. Our study may provide useful insights to clarify the uncertain characteristics of some eruptions in the past or to detect the occurrence of large, undocumented volcanic eruptions throughout the Andes.     

Telomere dynamics in HIV-1 infected and uninfected chimpanzees measured by an improved method based on high-resolution two-dimensional calibration of DNA sizes

We developed an improved method for accurately measuring telomere lengths based on two-dimensional calibration of DNA sizes combined with pulsed field electrophoresis and quantitative analysis of high-resolution gel images. This method was used to quantify the length of telomeres in longitudinal samples of peripheral blood mononuclear cells (PBMCs) from five chimpanzees infected with human immunodeficiency virus type 1 (HIV-1) and three uninfected animals, 14 to 27 years of age. The average length of the telomere restriction fragments (TRF) of infected and uninfected chimpanzees were 11.7 ± 0.25 kbp, and 11.6 ± 0.61 kbp, respectively, and were about 1 kbp and 3 kbp longer than those of human infants and 30 year old adults, respectively. There was a trend of a slight decrease (30–60 bp per year) in the TRF of two HIV infected chimpanzees over 30–35 months, while the TRF of one naive chimpanzee slightly increased over 20 months. Although the number of chimpanzees in this study is small and no statistically significant linear dependencies on time were observed, it appears that in chimpanzees, rates of shortening of the TRF are comparable or smaller than in adult humans and are not significantly affected by HIV-1 infection, which may be related to the inability of HIV-1 to cause disease in these animals.     

Immunocontraception and increased longevity in equids

Intensive population management by means of fertility control has been shown to change the age profile of a wild horse herd. The primary change has been an increase in the number and percent of older animals, as expected, but also the appearance of new and older age classes. An examination of direct effects of fertility control on two groups of treated animals shows a significant increase in longevity over non‐treated animals that is associated with contraceptive treatment. The mean age at death (MAD) was calculated for 128 wild horses for which precise birth and death dates were known, including 56 stallions, 42 untreated mares, 11 mares treated with a porcine zona pellucida contraceptive vaccine for 1–2 years, and 19 mares treated with the same vaccine for ≥3 years. The MAD for stallions (10.3±0.84 [SEM] years), and mares treated for 1–2 years (10.2±0.56), was significantly greater (P<0.05) than for untreated mares (6.4±0.85), and significantly <19.9±1.66 for mares treated ≥3 years (19.9±1.66). Zoo Biol 26:237–244, 2007. © 2006 Wiley‐Liss, Inc.     

Age Distribution of Naturally Occurring Acute Babesiosis in Cattle in Sweden

The age distribution of clinical cases of babesiosis reported by local veterinary practitioners was investigated in 1976 and 1981. The first study was based on material collected primarily for identifying the Babesia species, the second on computerized reports from a part of one county in Sweden. The results were similar. Most diseased animals, 135/165 (82%) and 145/161 (90%) respectively, were more than 2.5 years old (cows), while 27/165 (169b) and 12/161 (8%) respectively, were 1–2.5 years old and only 3–4 (2–3%) animals were calves less than 1 year old. This age group, however, probably did not meet the same infection risk as did older animals. Among cows (>2.5 years old) there seemed to be no influence of age on the distribution of clinical babesiosis. Calculation based upon the entire animal population of the county investigated in 1981 revealed that clinical babesiosis was reported about 11 times more often among cows than among heifers and steers. The comparatively high resistance among 1–2.5 year–old cattle may be a function of an inverse age resistance, and/or may be influenced by vaccination against babesiosis on »high risk« farms in Sweden and a lower risk of infection on other farms such that animals tend to escape infection prior to adultness. Babesia organisms were found in 156 of 165 cases (95%) reported as clinical babesiosis.     

Killer whale (Orcinus orca) reproduction at Sea World

Sea World has maintained killer whales (Orcinus orca) since 1965. The total killer whale inventory (1965–1993) has included 39 whales (25 females, 14 males); 28 were wild-caught and 11 captive-born, including one second-generation calf. As of September, 1993, there were 19 whales in the breeding program. Ten of these whales (53%) were captive-born, either at Sea World or other facilities in North America. The live wild-caught whales ranged in estimated age from 12–27 years (x? ± sd = 17.6 ± 4.2 years). The captive-born whales ranged in age from <1 to 8 years. In the Sea World breeding program (through September, 1993), there have been nine live births and one stillbirth, with eight calves part of the current inventory. Births occurred from July to February. Calving intervals ranged from 32–58 months. Female age at birth of first calves ranged from 8 years to an estimated 17 years (x? ± sd = 12.7 ± 3.0 years). Gestation, based on conception estimates from serum progesterone analysis, averaged 17 months (x? ± sd = 517 ± 20 days), but successful pregnancies with viable calves occurred from 15–18 months (468–539 days). Females, in the presence and absence of males, were polyestrus with periods of cycling interspersed with individually variable noncycling (presumed anestrous) periods ranging from 3–16 months. Mean serum progesterone levels (±se) were as follows: noncycling periods = 121 ± 20 pg/ml; peak elevations during nonconceptive ovulatory (estrous) cycles = 3,962 ± 2,280 pg/ml; first pregnancies = 14,592 ± 3,854 pg/ml; second pregnancies = 8,389 ± 395 pg/ml; and third pregnancy = 8,180 ± 4,556. © 1995 Wiley-Liss, Inc.     

Effect of Net-Gun Capture on Survival of Mule Deer

Capture techniques to deploy radio-collars often risk mortality and injury to the animal. Capture-induced mortality can affect population sizes but also introduces bias in survival estimates based on data from captured animals. In recent years, a large-scale research and monitoring project in Utah, USA, has involved capturing and radio-collaring hundreds of mule deer (Odocoileus hemionus), a species of great interest in large parts of North America. Our objective was to investigate how the survival rates of these mule deer were affected by capture and handling. During winters of 2014–2018, an experienced capture crew net-gunned and fitted 1,805 animals with global positioning system (GPS)-collars. We estimated survival rates during the first 6 weeks after capture using Cox proportional hazard regression, and compared the survival rates of animals that were captured in a particular year to those of animals that were not captured but fitted with a GPS-collar in a previous year. We used a model selection framework to evaluate how long survival rates of captured animals were different from those of animals that were not captured. Our results indicated that weekly survival rates of captured animals were 0.985 ± 0.003 (SE), 0.988 ± 0.002, and 0.990 ± 0.001 in weeks 1, 2 and 3, respectively. Weekly survival rates of captured deer during weeks 4–6 were 0.993 ± 0.001, the same as those of deer that were not captured at the same time. Furthermore, post-capture survival rates were positively influenced by body size and negatively influenced by age. We conclude that the mortality resulting from helicopter capture was low but recommend comparing newly captured and previously captured individuals to examine what proportion of observed mortality is likely capture-related. © 2020 The Wildlife Society.     

Dental eruption in captive-bornCebus apella: From birth to 30 months old

This work reports on the ages of gingival eruption of deciduous and permanent teeth observed from the time of birth until 30 months old, captive-born individuals. All of the animals were born with the protrusive di₁ already through the gingival border. The dmp⁴ were the last teeth of the deciduous series which emerged at 24.5±3.11 weeks in the males and 27.8±2.95 weeks in the females. Significant sexual differences were found between the eruption period of the dpm₂, dmp⁴ (p<0.05), and dpm₄ (p<0.01), with the males being more precocious than the females. The first permanent tooth that emerged, usually, was the M₁ at 13.50±2.12 months in the males, and 14.00±0.82 months in the females. At 30 months of age, not one individual had replaced his deciduous canine or premolar teeth with the permanent ones, and, moreover, the M ₃ ³ had not yet emerged.