The potential for abiotic organic synthesis and biosynthesis at seafloor hydrothermal systems

Calculations are presented of the extent to which chemical disequilibria are generated when submarine hydrothermal fluids mix with sea water. These calculations involve quantifying the chemical affinity for individual reactions by comparing equilibrium compositions with the compositions of mixtures in which oxidation–reduction reactions are inhibited. The oxidation–reduction reactions that depart from equilibrium in these systems provide energy for chemotrophic microbial metabolism. Methanogenesis is an example of this phenomenon, in which the combination of carbon dioxide, hydrogen and methane induced by fluid mixing is far from equilibrium, which can be approached if more methane is generated. Similarly, the production of other organic compounds is also favorable under the same conditions that permit methanogenesis. Alkanes, alkenes, alcohols, aldehydes, carboxylic acids and amino acids are among the compounds that, if formed, would lower the energetic state of the chemical composition generated in mixed fluids. The resulting positive values of chemical affinity correspond to the thermodynamic drive required for abiotic organic synthesis. It is also possible that energy release accompanies biosynthesis by chemotrophic organisms. In this way, hydrothermal ecosystems differ radically from familiar ecosystems at Earth's surface. If captured, the energy released may be sufficient to drive biosynthesis of carbohydrates, purines, pyrimidines and other compounds which require energy inputs.     

贵州麻江高枧夏家史考

“树由根而发,水由源而流”,当紫禁城里传出贵州麻哈州人夏同袜高中状元之时,祝贺之余要思考的便是原因,固然夏状元本人是成就这一巅峰时刻的本因,然他身后的那个家族对他的影响亦不容忽视。历史沧桑变幻,关于夏状元以及他的那个家族已经变得愈加模糊,便是他的后世子孙对他亦是不甚清楚。纵有热心人士努力,但不成系统,本文试图为夏家600余年的历史理出一个脉络,希望抛砖引玉,以此为起点展开对夏状元及其家族的研究,作为600百年前来到贵州的汉族,这个家族的成长发展具有一定的典型意义,具有较高的研究价值。     

Genetic relationships based on discrete dental traits: Basketmaker II and Mimbres

Investigations of the relationships between culture and biology among prehistoric populations of the southwestern United States can enhance our reconstruction of social interactions. The present study analyses the permanent dentition of Basketmaker II and Mimbres individuals from multiple sites using the Arizona State University dental anthropology system, and compares them with a regional sample. Discrete dental trait analysis provides a useful means for assessing the degree of genetic relatedness between populations when large comparative samples are available. Both in situ cultural change and population replacement have been posited as the dominant mechanism acting on Basketmaker and early Puebloan groups. We examine the relationship of these populations to probable Uto‐Aztecan speakers in light of the Uto‐Aztecan farmer migration hypothesis. The Basketmaker II complex, traditionally recognised as a distinct cultural unit, exhibits considerable population heterogeneity. Western Basketmakers appear to share biological ties with Uto‐Aztecan speakers, while Eastern Basketmakers do not, as predicted by the model. The relationship of the Mimbres to probable Uto‐Aztecan speakers is less clear because the Mimbres show only weak affinities to northern Mexican populations. Copyright © 2007 John Wiley & Sons, Ltd.     

The ancient inhabitants of Jebel Moya redux: measures of population affinity based on dental morphology

This paper reexamines some of the methods and craniometric findings in the classic volume The Ancient Inhabitants of Jebel Moya (Sudan) (1955) by Mukherjee, Rao & Trevor, in light of recent archaeological data and relative to a new dental morphological study. Archaeological evidence characterises these inhabitants as having been heavily influenced by outside sources; yet they managed to establish and maintain their own distinctive culture as seen in the site features and surviving artefact collections. The dental study, modelled after the original craniometric‐based investigation and using the same or similar comparative samples, detected complementary indications of outside biological influence. In the study, up to 36 dental traits were recorded in a total of 19 African samples. The most influential traits in driving inter‐sample variation were then identified, and phenetic affinities were calculated using the Mahalanobis D² statistic for non‐metric traits. If phenetic similarity provides an estimate of genetic relatedness, these affinities, like the original craniometric findings, suggest that the Jebel Moyans exhibited a mosaic of features that are reminiscent of, yet distinct from, both sub‐Saharan and North African peoples. Together, these different lines of evidence correspond to portray the Jebel Moya populace as a uniform, although distinct, biocultural amalgam. Copyright © 2006 John Wiley & Sons, Ltd.     

Population affinities of Parsis in the Indian subcontinent

The present study was an attempt to document changes in frequencies of dental morphology traits and understand phenetic affinities of Parsis, who migrated to the Indian subcontinent around the 8th century. Despite successfully integrating themselves into the Indian society, they have retained their ethnicity and distinct cultural practices. This study was conceived as a result of an excavation at the site of Sanjan, Gujarat which, as per historical records, is believed to be the first town in the Indian subcontinent with a large Parsi settlement thereby facilitating a diachronic comparison between the ancestral and extant Parsi groups. We compared and analysed dental traits between the two groups expecting a very close relationship between them owing to their ancestor–descendent relationship. Eleven discrete dental traits were selected and scored using the Arizona State University Dental Anthropology System (ASUDAS). Frequency changes were assessed by comparing trait frequencies; whereas phenetic affinity between Parsis was assessed by statistically comparing them with 13 populations using Smith's mean measure of divergence (MMD) statistic. Comparison of dental trait frequencies between Sanjan and extant Parsi samples show significant differences in incisor morphology, Carabelli cusp and Hypocone development. Trait frequencies, MMD values and 2D multidimensional scaling (MDS) plot indicate that extant Parsis and Sanjan samples are distantly separated from each other. Extant Parsis show closer affinity to low caste Mahars and tribal Madia Gonds than South and Central Asian groups. Sanjan is distant from all other groups including extant Parsis. It is likely that genetic drift accentuated by their small numbers and strict endogamy has resulted in divergence of Parsi groups. Similarly, their convergence with Maharashtran groups indicates admixture of Parsis with local groups, which supports earlier conducted mtDNA studies. Copyright © 2009 John Wiley & Sons, Ltd.