抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Articles O ne of the primary causes of global environmental change is tropical deforestation, but the question of what factors drive deforestation remains largely unanswered (NRC 1999). Various hypotheses have produced rich arguments , but empirical evidence on the causes of deforestation continues to be largely based on cross-national statistical In some cases, these analyses are based on debatable data on rates of forest cover change (Palo 1999). The two major, mutually exclusive—and still unsatisfactory—explanations for tropical deforestation are single-factor causation and irre-ducible complexity. On the one hand, proponents of single-factor causation suggest various primary causes, such as shift-On the other hand, correlations between deforestation and multiple causative factors are many and varied , revealing no distinct pattern In addition to chronicling these attempts to identify general causes of deforestation through global-scale statistical analyses, the literature is rich in local-scale case studies investigating the causes and processes of forest cover change in specific localities. Our aim with this study is to generate from local-scale case studies a general understanding of the prox-imate causes and underlying driving forces of tropical deforestation while preserving the descriptive richness of these studies. Proximate causes are human activities or immediate actions at the local level, such as agricultural expansion, that originate from intended land use and directly impact forest cover. Underlying driving forces are fundamental social processes, such as human population dynamics or agricultural policies, that underpin the proximate causes and either operate at the local level or have an indirect impact from the national or global level. We analyzed the frequency of proximate causes and underlying driving forces of deforestation, including their interactions , as reported in 152 subnational case studies. We show that tropical deforestation is driven by identifiable regional patterns of causal factor synergies, of which the most prominent are economic factors, institutions, national policies, and remote influences (at the underlying level) driving agricultural expansion, wood extraction, and infrastructure extension (at the proximate level). Our findings reveal that prior stud-Helmut Geist (e-mail: geist@geog.ucl.ac.be) is a postdoctoral researcher (geography) in the field of human drivers of global environmental change and executive director of the Land Use and Cover Change (LUCC) core project of the International Geosphere-Biosphere Eric Lambin is a professor of geography with research interests in remote sensing and human ecology applied to studies of deforestation, desertification, and bio-mass burning in tropical regions. He is the chair of the IGBP and IHDP …

https://bioone.org/journalArticle/Download?fullDOI=10.1641%2f0006-3568(2002)052%5b0143%3aPCAUDF%5d2.0.CO%3b2

Proximate causes and underlying driving forces of tropical deforestation.

Enchantment and Disenchantment: The Role of Community in Natural Resource Conservation

The intention of this work is to show that European expansion not only transformed the historical trajectory of non-European societies but also reconstituted the historical accounts of these societies before European intervention. It asserts that anthropology must pay more attention to history.

Europe and the People without History

Conversion of natural habitats into agricultural and industrial landscapes, and ultimately into degraded land, is the major impact of humans on the natural environment, posing a great threat to biodiversity. The emerging discipline of restoration ecology provides a powerful suite of tools for speeding the recovery of degraded lands. In doing so, restoration ecology provides a crucial complement to the establishment of nature reserves as a way of increasing land for the preservation of biodiversity. An integrated understanding of how human population growth and changes in agricultural practice interact with natural recovery processes and restoration ecology provides some hope for the future of the environment.

https://science.sciencemag.org/content/sci/277/5325/515.full.pdf

Hopes for the Future: Restoration Ecology and Conservation Biology

Contemporary humans exhibit spectacular biological success derived from cumulative culture and cooperation. The origins of these traits may be related to our ancestral group structure. Because humans lived as foragers for 95% of our species' history, we analyzed co-residence patterns among 32 present-day foraging societies (total n = 5067 individuals, mean experienced band size = 28.2 adults). We found that hunter-gatherers display a unique social structure where (i) either sex may disperse or remain in their natal group, (ii) adult brothers and sisters often co-reside, and (iii) most individuals in residential groups are genetically unrelated. These patterns produce large interaction networks of unrelated adults and suggest that inclusive fitness cannot explain extensive cooperation in hunter-gatherer bands. However, large social networks may help to explain why humans evolved capacities for social learning that resulted in cumulative culture.

https://science.sciencemag.org/content/sci/331/6022/1286.full.pdf

Co-Residence Patterns in Hunter-Gatherer Societies Show Unique Human Social Structure

Preface - Thomas N Headland, Kenneth L Pike and Marvin Harris Introduction - Thomas N Headland A Dialogue Between Kenneth Pike and Marvin Harris on Emics and Etics PART ONE: THE DIALOGUE On the Emics and Etics of Pike and Harris - Kenneth L Pike Emics and Etics Revisited - Marvin Harris Pike's Reply to Harris - Kenneth L Pike Harris's Reply to Pike - Marvin Harris PART TWO: HISTORY AND SIGNIFICANCE OF EMICS AND ETICS Imposed Etics, Emics, Derived Etics - John W Berry Their Conceptual and Operational Status in Cross-Cultural Psychology Emic Analysis and the Limits of Cognitive Diversity - Robert Feleppa Emics, Etics, and Openness - Dell H Hymes An Ecumenical Approach Emics and Etics - James Lett Notes on the Epistemology of Anthropology Anthropology, Evangelization, and Abortion - Gerald F Murray The Grounding of Emics and Etics The Phoneme's Long Shadow - Willard V Quine The Emic-Etic Distinction as Applied to Language - Nira Reiss PART THREE: A FINAL RESPONSE Pike's Final Response - Kenneth L Pike Harris's Final Response - Marvin Harris

Emics and Etics the Insider/Outsider Debate

Hunter-Gatherers and Their Neighbors from Prehistory to the Present [and Comments and Replies]

It has been generally assumed until recently that tropical rain forests are food-rich biomes for human foragers, and that prehistoric hunter-gatherers once lived completely independent of cultivated foods in such environments. An alternative hypothesis that such forests are actually food-poor for humans is proposed here. Specifically, that wild starch foods such as yams were so scarce and so hard to extract that human foragers could not have lived in such biomes without recourse to cultivated foods. The symbiotic relationship found today between tropical forest hunter-gatherers and farmers is not a recent phenomenon, but evolved long ago as an adaptive strategy for successfully exploiting the tropical forest.

The Wild Yam Question: How Well Could Independent Hunter-Gatherers Live in a Tropical Rain Forest Ecosystem?

It is widely assumed that modem hunter-gatherer societies lived until very recently in isolation from food-producing societies and states and practiced neither cultivation, pastoralism, nor trade. This paper brings together data suggesting a very different model of middle to late Holocene hunter-gatherer economy. It is argued that such foraging roups were heavily dependent upon both trade with food-producing populations and part-time cultivation or pastoralism. Recent publications on a number of huntergatherer societies establish that the symbiosis and desultory food production observed among them today are neither recent nor anomalous but represent an economy practiced by most huntergatherers for many hundreds, if not thousands, of years. Psychological and political reasons for Westerners' attachment o the myth of the \"Savage Other\" are discussed.

/pdf/hunter-gatherers-and-their-neighbors-from-prehistory-to-the-53d1trw0b8.pdf

Thomas N. Headland

Papers

Co-Residence Patterns in Hunter-Gatherer Societies Show Unique Human Social Structure

Emics and Etics the Insider/Outsider Debate

Hunter-Gatherers and Their Neighbors from Prehistory to the Present [and Comments and Replies]

The Wild Yam Question: How Well Could Independent Hunter-Gatherers Live in a Tropical Rain Forest Ecosystem?

Hunter-Gatherers and Their Neighbors from Prehistory To the Present