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

A new statistical method for estimating divergence dates of species from DNA sequence data by a molecular clock approach is developed. This method takes into account effectively the information contained in a set of DNA sequence data. The molecular clock of mitochondrial DNA (mtDNA) was calibrated by setting the date of divergence between primates and ungulates at the Cretaceous-Tertiary boundary (65 million years ago), when the extinction of dinosaurs occurred. A generalized least-squares method was applied in fitting a model to mtDNA sequence data, and the clock gave dates of 92.3 +/- 11.7, 13.3 +/- 1.5, 10.9 +/- 1.2, 3.7 +/- 0.6, and 2.7 +/- 0.6 million years ago (where the second of each pair of numbers is the standard deviation) for the separation of mouse, gibbon, orangutan, gorilla, and chimpanzee, respectively, from the line leading to humans. Although there is some uncertainty in the clock, this dating may pose a problem for the widely believed hypothesis that the pipedal creature Australopithecus afarensis, which lived some 3.7 million years ago at Laetoli in Tanzania and at Hadar in Ethiopia, was ancestral to man and evolved after the human-ape splitting. Another likelier possibility is that mtDNA was transferred through hybridization between a proto-human and a proto-chimpanzee after the former had developed bipedalism.

Dating of the human-ape splitting by a molecular clock of mitochondrial DNA.

Border Gateway Protocol (BGP) is the protocol backing the core routing decisions on the Internet. It maintains a table of IP networks or 'prefixes' which designate network reachability among autonomous systems (AS). Point of concern in BGP is its lack of effective security measures which makes Internet vulnerable to different forms of attacks. Many solutions have been proposed till date to combat BGP security issues but not a single one is deployable in practical scenario. Any security proposal with optimal solution should offer adequate security functions, performance overhead and deployment cost. This paper critically analyzes the deployment issues of best three proposals considering trade-off between security functions and performance overhead.

Comparative analysis of

The revolution that wasn't: a new interpretation of the origin of modern human behavior.

Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.

Taphonomic and Ecologic Information Form Bone Weathering

The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto, Middle Awash, Ethiopia, that fill this gap and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens. Radioisotopically dated to between 160,000 and 154,000 years ago, these new fossils predate classic Neanderthals and lack their derived features. The Herto hominids are morphologically and chronologically intermediate between archaic African fossils and later anatomically modern Late Pleistocene humans. They therefore represent the probable immediate ancestors of anatomically modern humans. Their anatomy and antiquity constitute strong evidence of modern-human emergence in Africa.

Pleistocene Homo sapiens from Middle Awash, Ethiopia

Preface 1. Introduction 2. Field Procedures for Skeletal Remains 3. Ethics in Osteology 4. Bone Biology and Variation 5. Postmortem Skeletal Modification 6. Anatomical Terminology 7. Skull 8. Dentition 9. Hyoid and Vertebrae 10. Thorax: Sternum and Ribs 11. Shoulder Girdle: Clavicle and Scapula 12. Arm: Humerus, Radius, and Ulna 13. Hand: Carpals, Metacarpals, and Phalanges 14. Pelvic Girdle: Sacrum, Coccyx, and Os Coxae 15. Leg: Femur, Patella, Tibia, and Fibula 16. Foot: Tarsals, Metatarsals, and Phalanges 17. Osteological and Dental Pathology 18. Laboratory Procedures and Reporting 19. The Skeletal Biology of Individuals and Populations

The Human Bone Manual

Seventeen hominoid fossils recovered from Pliocene strata at Aramis, Middle Awash, Ethiopia make up a series comprising dental, cranial and postcranial specimens dated to around 4.4 million years ago. When compared with Australopithecus afarensis and with modern and fossil apes the Aramis fossil hominids are recognized as a new species of Australopithecus--A. ramidus sp. nov. The antiquity and primitive morphology of A. ramidus suggests that it represents a long-sought potential root species for the Hominidae.

Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia

Hominid fossils predating the emergence of Australopithecus have been sparse and fragmentary. The evolution of our lineage after the last common ancestor we shared with chimpanzees has therefore remained unclear. Ardipithecus ramidus, recovered in ecologically and temporally resolved contexts in Ethiopia's Afar Rift, now illuminates earlier hominid paleobiology and aspects of extant African ape evolution. More than 110 specimens recovered from 4.4-million-year-old sediments include a partial skeleton with much of the skull, hands, feet, limbs, and pelvis. This hominid combined arboreal palmigrade clambering and careful climbing with a form of terrestrial bipedality more primitive than that of Australopithecus. Ar. ramidus had a reduced canine/premolar complex and a little-derived cranial morphology and consumed a predominantly C3 plant-based diet (plants using the C3 photosynthetic pathway). Its ecological habitat appears to have been largely woodland-focused. Ar. ramidus lacks any characters typical of suspension, vertical climbing, or knuckle-walking. Ar. ramidus indicates that despite the genetic similarities of living humans and chimpanzees, the ancestor we last shared probably differed substantially from any extant African ape. Hominids and extant African apes have each become highly specialized through very different evolutionary pathways. This evidence also illuminates the origins of orthogrady, bipedality, ecology, diet, and social behavior in earliest Hominidae and helps to define the basal hominid adaptation, thereby accentuating the derived nature of Australopithecus.

https://science.sciencemag.org/content/sci/326/5949/64.full.pdf

Ardipithecus ramidus and the Paleobiology of Early Hominids

A large sample of Pliocene fossil hominid remains has been recovered from the African sites of Hadar in Ethiopia and Laetolil in Tanzania. These collections, dating approximately between 2.9 and 3.8 million years ago, constitute the earliest substantial record of the family Hominidae. This article assesses the phylogenetic relationships of the newly discovered fossil hominids and provides a taxonomy consistent with that assessment. A new taxon, Australopithecus afarensis, has been created to accommodate these Pliocene hominid fossils.

https://science.sciencemag.org/content/sci/203/4378/321.full.pdf

Tim D. White

Papers

Pleistocene Homo sapiens from Middle Awash, Ethiopia

The Human Bone Manual

Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia

Ardipithecus ramidus and the Paleobiology of Early Hominids

A systematic assessment of early African hominids