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1.
2.
The origins and dispersal of farming and pastoral nomadism in southwestern Asia are complex, and there is controversy about whether they were associated with cultural transmission or demic diffusion. In addition, the spread of these technological innovations has been associated with the dispersal of Dravidian and Indo-Iranian languages in southwestern Asia. Here we present genetic evidence for the occurrence of two major population movements, supporting a model of demic diffusion of early farmers from southwestern Iran-and of pastoral nomads from western and central Asia-into India, associated with Dravidian and Indo-European-language dispersals, respectively.  相似文献   

3.
Ethnic populations of India as seen from an evolutionary perspective   总被引:5,自引:0,他引:5  
It is now widely accepted that (i) modern humans,Homo sapiens sapiens, evolved in Africa, (ii) migrated out of Africa and replaced archaic humans in other parts of the world, and (iii) one of the first waves of out-of-Africa migration came into India. India, therefore, served as a major corridor for dispersal of modern humans. By studying variation at DNA level in contemporary human populations of India, we have provided evidence that mitochondrial DNA haplotypes based on RFLPs are strikingly similar across ethnic groups of India, consistent with the hypothesis that a small number of females entered India during the initial process of the peopling of India. We have also provided evidence that there may have been dispersal of humans from India to southeast Asia. In conjunction with haplotype data, nucleotide sequence data of a hypervariable segment (HVS-1) of the mitochondrial genome indicate that the ancestors of the present austro-asiatic tribal populations may have been the most ancient inhabitants of India. Based on Y-chromosomal RFLP and STRP data, we have also been able to trace footprints of human movements from west and central Asia into India.  相似文献   

4.
This paper explores the language practices, attitudes to languages and the inter-generational transmission of heritage languages amongst the UK-born adult children of refugee parents. The paper draws on empirical data from a research project based on 45 qualitative interviews with three groups of “second generation” refugees, whose parents came as Tamil refugees from Sri Lanka, Kurdish refugees from Turkey and as refugees from Vietnam. The paper explores the ways in which language is central to political discussions and to national policies on race, cohesion, diversity, “Britishness” and citizenship. These debates and policies ignore and often silence the positive role of heritage languages. This paper highlights the importance of heritage languages as a signifier for a number of wider issues of identity, which intersect with race and refugee backgrounds in complex ways.  相似文献   

5.
The Ho, a settled tribal group of Chota Nagpur, India, were tested for five genetic characters. Genetic distance among eleven tribal groups of Bihar, Orissa and Madhya Pradesh are calculated according to Edwards ('71). Affinities of these tribes are discussed taking into consideration the languages spoken by them. These breeding groups may have drifted apart along the paths of their dialect differentiations. Cultural and geographical factors further enhanced their isolation.  相似文献   

6.
2003~2004年在印度南部的50家农户进行了4次二化性家蚕品种农村试养,结果表明:供试品种生长发育经过较印度二化性家蚕品种慢,茧丝质优于印度对照种,适应性、抗逆性整体表现较印度对照种弱。由于气候、饲养技术、叶质等的差异,与其在国内的饲养相比,印度饲养试验中供试品种的各项性能指标均偏低,生产能力达不到国内水平。印度南部适宜饲养二化性家蚕的季节为9月至翌年的3月,进入4月后,不宜饲养二化性家蚕品种。  相似文献   

7.
Migration by Odonata has been recorded sporadically for several centuries, but only recently have new technologies and a new wave of interest in these ancient insects sparked a concerted effort to understand the extent, behavioral mechanisms, adaptive significance, and ecological consequences of this phenomenon. Here I review our current knowledge of these sometimes spectacular flights, focusing on the few species in North America that are known to migrate more or less annually. One of these, the Common Green Darner, Anax junius, has been shown to traverse hundreds to thousands of kilometers from north to south during fall migration. Pantala flavescens (Wandering Glider) is plausibly inferred to make an overseas flight from India to East Africa with the Northeast Monsoon, although its migrations in North America are less well understood. Large scale movements of these and other species raises questions about population connectivity, ecosystem impacts, the nature and evolution of cues that initiate migration, and effects of climate change on these phenomena.  相似文献   

8.
Monitoring and control of action by the frontal lobes   总被引:10,自引:0,他引:10  
Schall JD  Stuphorn V  Brown JW 《Neuron》2002,36(2):309-322
Success requires deciding among alternatives, controlling the initiation of movements, and judging the consequences of actions. When alternatives are difficult to distinguish, habitual responses must be overcome, or consequences are uncertain, deliberation is necessary and a supervisory system exerts control over the processes that produce sensory-guided movements. We have investigated these processes by recording neural activity in the frontal lobe of macaque monkeys performing a countermanding task. Distinct neurons in the frontal eye field respond to visual stimuli or control the production of the movements. In the supplementary eye field and anterior cingulate cortex, neurons appear not to control directly movement initiation but instead signal the production of errors, the anticipation and delivery of reinforcement, and the presence of processing conflict. These signals form the core of current models of supervisory control of sensorimotor processes.  相似文献   

9.
This article explores the consequences of rapidly fissuring binary models of community and progress in a national and global context. It suggests that this is a dominant (black/white) paradigm used to map both mainstream and particularly liminal sites of cultural/political articulation. Furthermore, it argues that such models of imputed progress, reason and civility contain the narcissistic residue of an earlier liberal encounter: namely, the fetish quality attached to the black body as abject text and privileged humanist ontology by the twentieth-century European movement of liberal humanism. The article argues that recent attempts to rethink this position vis à vis the European Holocaust have actually rehearsed the logic, both of fetish and binarism. Moreover, that this stasis in liberal thinking on issues of race and violence has heightened the attraction of those political movements characterized by cultural absolutism. The essay suggests that acknowledgement of the 'public secret' which underwrites liberal narrative stasis is the first step towards a more appropriate cultural grammar.  相似文献   

10.
The nomenclatures of the taxa of the mangrove Rhizophoraceae of India have been scrutinized and 20 names are lectotypified or neotypified. In addition, the holotypes of some names are located for the first time with clarifications provided. Since natural hybridization is common in Rhizophoraceae, its consequences for the correct application of names is also briefly discussed.  相似文献   

11.
Since 1998 there have been significant changes in the global distribution of bluetongue virus (BTV). Ten previously exotic BTV serotypes have been detected in Europe, causing severe disease outbreaks in naïve ruminant populations. Previously exotic BTV serotypes were also identified in the USA, Israel, Australia and India. BTV is transmitted by biting midges (Culicoides spp.) and changes in the distribution of vector species, climate change, increased international travel and trade are thought to have contributed to these events. Thirteen BTV serotypes have been isolated in India since first reports of the disease in the country during 1964. Efficient methods for preparation of viral dsRNA and cDNA synthesis, have facilitated full-genome sequencing of BTV strains from the region. These studies introduce a new approach for BTV characterization, based on full-genome sequencing and phylogenetic analyses, facilitating the identification of BTV serotype, topotype and reassortant strains. Phylogenetic analyses show that most of the equivalent genome-segments of Indian BTV strains are closely related, clustering within a major eastern BTV ‘topotype’. However, genome-segment 5 (Seg-5) encoding NS1, from multiple post 1982 Indian isolates, originated from a western BTV topotype. All ten genome-segments of BTV-2 isolates (IND2003/01, IND2003/02 and IND2003/03) are closely related (>99% identity) to a South African BTV-2 vaccine-strain (western topotype). Similarly BTV-10 isolates (IND2003/06; IND2005/04) show >99% identity in all genome segments, to the prototype BTV-10 (CA-8) strain from the USA. These data suggest repeated introductions of western BTV field and/or vaccine-strains into India, potentially linked to animal or vector-insect movements, or unauthorised use of ‘live’ South African or American BTV-vaccines in the country. The data presented will help improve nucleic acid based diagnostics for Indian serotypes/topotypes, as part of control strategies.  相似文献   

12.
Kinesin-2 is a major microtubule-based motor in most cell types. Its in vitro motile properties have been analyzed extensively and been found to differ considerably from kinesin-1. Although recombinant kinesin-2 heterodimers exhibit processive movement, the processivity of the native kinesin-2 holoenzyme has never been evaluated. Kinesin-2 can interact with dynactin, a 'processivity factor' for cytoplasmic dynein, which may alter its motile properties. In this study, we analyze the in vitro motility of single native kinesin-2 molecules and determine the effects of dynactin on motor processivity. We find that individual native kinesin-2 molecules travel processively. Dynactin has no effect on velocity but significantly increases the run length of kinesin-2 movements. These results show that the interaction with dynactin has important functional consequences on the activity of the kinesin-2 motor.  相似文献   

13.
Complexity and variation in loggerhead sea turtle life history   总被引:4,自引:0,他引:4       下载免费PDF全文
Juvenile loggerhead sea turtles spend more than a decade in the open ocean before returning to neritic waters to mature and reproduce. It has been assumed that this transition from an oceanic to neritic existence is a discrete ontogenetic niche shift. We tested this hypothesis by tracking the movements of large juveniles collected in a neritic foraging ground in North Carolina, USA. Our work shows that the shift from the oceanic to neritic waters is both complex and reversible; some individuals move back into coastal waters and then return to the open ocean for reasons that are still unclear, sometimes for multiple years. These findings have important consequences for efforts to protect these threatened marine reptiles from mortality in both coastal and open-ocean fisheries.  相似文献   

14.
India represents an intricate tapestry of population substructure shaped by geography, language, culture, and social stratification. Although geography closely correlates with genetic structure in other parts of the world, the strict endogamy imposed by the Indian caste system and the large number of spoken languages add further levels of complexity to understand Indian population structure. To date, no study has attempted to model and evaluate how these factors have interacted to shape the patterns of genetic diversity within India. We merged all publicly available data from the Indian subcontinent into a data set of 891 individuals from 90 well-defined groups. Bringing together geography, genetics, and demographic factors, we developed Correlation Optimization of Genetics and Geodemographics to build a model that explains the observed population genetic substructure. We show that shared language along with social structure have been the most powerful forces in creating paths of gene flow in the subcontinent. Furthermore, we discover the ethnic groups that best capture the diverse genetic substructure using a ridge leverage score statistic. Integrating data from India with a data set of additional 1,323 individuals from 50 Eurasian populations, we find that Indo-European and Dravidian speakers of India show shared genetic drift with Europeans, whereas the Tibeto-Burman speaking tribal groups have maximum shared genetic drift with East Asians.  相似文献   

15.
It has been suggested that children with autism orient towards audiovisual synchrony (AVS) rather than biological motion and that the opposite pattern is to be expected in typical development. Here, we challenge this notion by showing that 3-year-old neurotypical children orient to AVS and to biological motion in point-light displays but that 3-year-old children with autism orient to neither of these types of information. Thus, our data suggest that two fundamental mechanisms are disrupted in young children with autism: one that supports orienting towards others’ movements and one that supports orienting towards multimodally specified events. These impairments may have consequences for socio-cognitive development and brain organization.  相似文献   

16.
Accelerated loss of sea ice in the Arctic is opening routes connecting the Atlantic and Pacific Oceans for longer periods each year. These changes may increase the ease and frequency with which marine birds and mammals move between the Pacific and Atlantic Ocean basins. Indeed, recent observations of birds and mammals suggest these movements have intensified in recent decades. Reconnection of the Pacific and Atlantic Ocean basins will present both challenges to marine ecosystem conservation and an unprecedented opportunity to examine the ecological and evolutionary consequences of interoceanic faunal exchange in real time. To understand these changes and implement effective conservation of marine ecosystems, we need to further develop modeling efforts to predict the rate of dispersal and consequences of faunal exchange. These predictions can be tested by closely monitoring wildlife dispersal through the Arctic Ocean and using modern methods to explore the ecological and evolutionary consequences of these movements.  相似文献   

17.
The biases of individual language learners act to determine the learnability and cultural stability of languages: learners come to the language learning task with biases which make certain linguistic systems easier to acquire than others. These biases are repeatedly applied during the process of language transmission, and consequently should effect the types of languages we see in human populations. Understanding the cultural evolutionary consequences of particular learning biases is therefore central to understanding the link between language learning in individuals and language universals, common structural properties shared by all the world’s languages. This paper reviews a range of models and experimental studies which show that weak biases in individual learners can have strong effects on the structure of socially learned systems such as language, suggesting that strong universal tendencies in language structure do not require us to postulate strong underlying biases or constraints on language learning. Furthermore, understanding the relationship between learner biases and language design has implications for theories of the evolution of those learning biases: models of gene-culture coevolution suggest that, in situations where a cultural dynamic mediates between properties of individual learners and properties of language in this way, biological evolution is unlikely to lead to the emergence of strong constraints on learning.  相似文献   

18.
The changeable biogeography of the Ordovician is reviewed, quantitatively analysed and used to assess possible positions and relative movements of the continental plates. Plate boundaries are defined as precisely as possible using geological and palaeontological data. The trilobites, corals, brachiopods, cephalopods, echinoderms, graptolites and ostracods are found to be useful in defining plate boundaries and relative plate movements. Oceanic barriers are considered to be the simplest explanation for the maintenance of faunal provincialisms. The faunal barriers between South America and Africa and between Australia and Gondwanaland may have been climatic and land barriers. The present Asian continent is divided into Kazakhstan, the Siberian Platform, South Asian, Northern China, India and the Jano-Kolymian block. These areas had different faunal histories and are considered to have had different drift histories. The North China and South Asian plates were separated by the Tsinling Ocean, the Northern European plate from the North American plate by Wilson's Proto-Atlantic and the Siberian Platform plate from the Northern European by the Uralian Ocean. Southern and Central Europe are shown to have been joined to Africa and separated from the Northern European plate by a Mid-European Ocean. If Australia is considered as part of an Ordovician Gondwanaland then the best explanation for the faunal histories of most plates is provided by an anticlockwise rotation of Gondwanaland about the South palaeo-pole.  相似文献   

19.
Vedic and early post-Vedic Sanskrit works describe Indo-Aryan life in northern India during 2000–200 B.C. Wild and cultivated plants of the Cucurbitaceae played an important role in Indo-Aryan food, medicine, and culture; over 300 words describing cucurbits are found in the Sanskrit texts. These words, their etymological relationships, and the geographies of the cucurbit taxa were compared. Results indicate that the Indo-Aryas knew only a handful of cucurbits before entering the Indian subcontinent from the west. They learned of at least 11 more species from their neighbors in India, who were speakers of Dravidian or Munda languages.  相似文献   

20.
Indigenous languages are powerful symbols of self-determination and sovereignty for tribal communities in the United States, and many community-based programs have been developed to support and maintain them. The successes of these programs, however, have been difficult to replicate at large research institutions. This article examines the issues of incorporating Indigenous languages into the university system by focusing on a series of language events developed as part of the Ojibwe language program at Michigan State University. These language events demonstrate a way for communities to participate in and maintain control of Indigenous language programs despite their location in nontribal educational institutions.  相似文献   

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