Spatio-temporal variation in the preservation of ancient faunal remains

Palaeodemographic studies of animals using frequency distributions of radiocarbon dates are increasingly used in studies of Quaternary extinction but are complicated by taphonomic bias, or the loss of material through time. Current taphonomic models are based on the temporal frequency distributions of sediments, but bone is potentially lost at greater rates because not all sedimentary contexts preserve bone. We test the hypotheses that (i) the loss of bone over time is greater than that of sediment and (ii) this rate of loss varies geographically at large scales. We compiled radiocarbon dates on Pleistocene-aged bone from eastern Beringia (EB), the contiguous United States (CUSA) and South America (SA), from which we developed models of taphonomic loss. We find that bone is lost at greater rates than terrestrial sediment in general, but only for CUSA and SA. Bone in EB is lost at approximately the same rate as terrestrial sediments, which demonstrates the excellent preservation environments of arctic regions, presumably due to preservative effects of permafrost. These differences between bone and sediment preservation as well as between arctic and non-arctic regions should be taken into account by any research addressing past faunal population dynamics based on temporal frequency distributions.     

陕西大原村制陶遗址人骨的古病理学

本文针对陕西省西安市西咸新区丰京西周大原村制陶遗址出土的 30 例保存相对完整的人骨;运用裸眼与 Dino-Lite 显微镜观察相结合的方式;记录其古病理指征。结果表明;该遗址多数个体存在筛状眶;部分伴有颅外多孔现象;暗示该人群营养状况不良且生活环境恶劣;较高的肋骨骨膜炎和上颌窦炎患病率可能源于环境污染所致的呼吸系统感染。该人群跖骨跪踞面出现率较高;跖趾关节使用频繁。骨关节炎多发于脊柱关节、踝关节、肩关节和髋关节;体现出遗址居民关节劳动负荷较大。掌骨异常弯曲;指骨和肢骨上可见肌肉骨骼应力标志(MSM)的骨性证据;此类特殊骨性改变显示这些个体曾从事关节运动重复率高且需大量运用手部肌肉组织的工作。这些疾病特征与制陶职业紧密相关。     

The MAD legacy: How meaningful is mean age-at-death in skeletal samples

This study examines the representativeness of palaeodemographic reconstructions from human skeletal remains. Mean age-at-death (MAD) is the primary statistic used in interpretations of changing patterns of health and well being from palaeodemographic analyses. A series of sampling experiments were conducted on three documented 19th century samples representing the total cemetery population from which skeletal samples could be drawn. Comparisons of the age-at-death distributions of simulated skeletal samples to the parent population were made to assess the relative magnitude of deviation associated with different types of bias (age, sex, temporal). From the examples presented, variability in age-at-death distribution is high in samples of less than 100, suggesting that for samples of less than 100analyzable individuals, it is probable that the mortality profiles constructed are not an accurate reflection of the cemetery. It is proposed that whateverprocess mean age-at-death reflects for past populations (fertility or mortality), is irrelevant if the sample on which the statistic is calculated is not representative of the population. Given that most cemetery samples will be subject, differentially, to biases at a variety of levels, comparative studies based on palaeodemographic data cannot be considered reliablewithout careful control for those biases. It is suggested that representativeness is the primary theoretical obstacle for researches to overcome, and that it is necessary to shift our focus to rigorously exploring those factors that bias our samples. Without some direct quantification of the representativeness of a sample, palaeodemographic estimators such as mean age-at-death are meaningless and any subsequent interpretations regarding the past, dubious at best.     

On the possibility of the MN blood group determination in human bones

After a series of preliminary tests on inert substances and on saliva drawn from donors of know MN blood group, 31 right femura from Pisa cemetery buried for 25–30 years and 37 eneolithic femura from Gaudo necropolis near Paestum (2500 – 2000 B.C.) were submitted to 140 assays for the MN system using the standard technique already devised in our Laboratory for ABO blood group determination.Positive and reproducible results were obtained in 18:31 recent femura (58%) and in 24:37 eneolithic bones (65%). The following phenotype and gene frequencies were obtained:

$\text{recent femura:}\text{8.}\text{M}\text{+3.}\text{N}\text{+7.}\text{MN}\text{=18; 0·64m+0.·36n=1}$

$\text{eneolithic femura:}\text{9.}\text{M}\text{+6.}\text{N}\text{+9.}\text{MN}\text{=24; 0·56m+0·44n=1}$

When the ABO and the MN blood group determinations are performed in parallel, a significant positive connection between the two diagnosabilities is observable: P = 0·0387 in the case of the eneolithic bones, $\text{P ? 0·02}$ in the case of the total sample of 59 eneolithic and recent bones tested in parallel. This fact could be reasonably explained considering the similarity of the chemical structure of MN and ABO glycoproteins, which would account for a similar behaviour in preservation.The absence or the very low concentration of M and N substances in tissues and body fluids would on the other hand agree with the percentage of diagnosability: lower in the MN system (60–65%) than in the ABO system (75–80%). The more problematical character of MN blood group typing of bones could be better approached if further research were done.     

The use of protein characteristics to assess the retrievability of ancient DNA from ancient bones

The ability to retrieve DNA from ancient specimens has been one of the greatest achievements of the past decade, and has opened a totally new field of research with applications in seemingly distant domains such as archeobotany, the molecular phylogeny of extinct genomes, human paleopathology and the genetic of ancient human populations. However, extraction of ancient DNA has often a very low rate of success, prompting researchers to develop screening methods for the selection of promising specimens. With this goal in mind, we studied the amino acid content of nine human bones of ancient origin. We demonstrate that a single HPLC chromatogram is indicative of the integrity of ancient bone proteins. Among five specimens containing amplifiable DNA, four exhibited a protein content similar to that of contemporary bone protein content. Three of the four specimens, from which we were unable to extract any amplifiable DNA, had an amino acid content strikingly different from that of contem-porary bone. A non-parametric statistical test, Kendall's tau, was used to show that protein content and PCR products, are probably correlated (at a 95% confidence level). In addition, the D/L Asp and D/L Glu racemization ratios obtained are indicative of the presence of ancient organic compounds. We propose that protein analysis should be systematically performed in studies where there are many samples in order to select the specimens that are most likely to contain retrievable ancient DNA.     

河南栾川孙家洞遗址出土的穿孔标本

孙家洞遗址初步测年为40万年左右,出土了少量石制品、古人类牙齿以及大量动物化石,其中一件骨骼标本存在非常规整的穿孔,其整体形态和大小与人工穿孔比较相似。通过系统的宏观观测与显微镜下分析,并与已明确性质的考古标本(自然穿孔和人工穿孔标本)和实证材料(现代鬣狗洞发掘出土材料)进行对比后发现,孙家洞遗址出土的穿孔标本与食肉类啃咬、甲虫类啮食以及人工造成的穿孔标本存在明显差异,而具备了被鬣狗胃酸腐蚀标本的所有典型特征。