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To learn the evolutionary trajectories of caste differentiation in eusocial species is a major goal of sociobiology. We present an explanatory framework for caste evolution in the eusocial wasp genus Polistes (Vespidae), which is a model system for insect eusocial evolution. We hypothesize that Polistes worker and gyne castes stem from two developmental pathways that characterized the bivoltine life cycle of a solitary ancestor. Through individual-based simulations, we show that our mechanistic framework can reproduce colony-level characteristics of Polistes and, thereby, that social castes can emerge from solitary regulatory pathways. Our explanatory framework illustrates, by specific example, a changed perspective for understanding insect social evolution.

A surprising report in a contentious area of developmental biology has sparked a scientific misconduct investigation at the University of Missouri, placing the results of the implicated paper, published in Science earlier this year, in limbo. (Read more.)

ANTHROPOLOGYAn analysis on page [1662][1] of this week's issue of Science concludes that 6-million-year-old Orrorin tugenensis was indeed an early ancestor of humans. But it challenges a controversial proposal that Orrorin gave rise to our genus, Homo , directly. [1]: http://www.sciencemag.org/cgi/content/short/319/5870/1662

Miller considers why China has not reaped many of the economic and social benefits of urbanization.

They have been called the most famous papers that were never published. But now, one of two controversial studies that shows how to make H5N1 avian influenza more transmissible in mammals is up on Nature9s Web site for all the world to scrutinize—including, some worry, would-be bioterrorists who might use the information to set off a pandemic. The other paper received a crucial go-ahead from the Dutch government last week and will likely be published by Science soon.

Sapp explores how molecular methods have changed our understanding of microbial genetics and genomics and the large-scale relationships among microbes.

Scientific PublishingA newly developed research tool called a reactome array, which has attracted widespread interest from biologists, has come under intense fire from scientists who say the [description][1] of the device in the 9 October issue of Science includes "impossible" chemical reactions and makes little sense. The publication drew immediate attention because the array promises to establish the functions of a myriad of enzymes and probe the metabolism of bacteria and other kinds of cells. Last week, Science acknowledged the furor, publishing online an "[Editorial Expression of Concern][2]" in which the journal's editor-in-chief, Bruce Alberts, notes that "serious questions have been raised about the methods and data presented." [1]: http://www.sciencemag.org/cgi/content/abstract/sci;326/5950/252 [2]: http://www.sciencemag.org/cgi/content/abstract/science.1186078

SEOUL AND TOKYO-- Embattled Korean stem cell scientist Woo Suk Hwang and his university have bowed to pressure for an investigation into a growing list of questions about a landmark paper he and colleagues published online in Science on 19 May 2005. (Read more.)

Drawing on a wide range of case studies, Simberloff offers nonspecialists a comprehensive survey of the biology and impact of invasive species.

Drawing on his extensive work with mammals and birds in diverse environments, McNab offers a personal perspective on comparative physiology and ecological energetics.

Collectively, these essays survey the current state and future prospects of the major areas within evolutionary biology.

After providing a historical perspective on the problem of DNA entanglement, Wang discusses structural, functional, and clinical aspects of topoisomerases.

Evans et al . and Mekel-Bobrov et al . (Reports, 9 September 2005, p. 1717 and 1720, respectively) reported that human genetic variants of Microcephalin ( MCPH1 ) and abnormal spindle-like microcephaly associated ( ASPM ) are under strong positive selection. We genotyped these variants in 9000 children and find no meaningful associations with brain size and various cognitive measures, which indicates that contrary to previous speculations, ASPM and MCPH1 have not been selected for brain-related effects.

Chong et al ., Nishio et al ., and Suri et al . (Reports, 24 March 2006, pp. 1774 , 1775 , and 1778 ) confirmed that treating nonobese diabetic (NOD) mice with an immune adjuvant and semisyngenic spleen cells can reverse the disease but found that spleen cells did not contribute to the observed recovery of pancreatic islets. We show that islet regeneration predominately originates from endogenous cells but that introduced spleen cells can also contribute to islet recovery.

Foundress associations and high frequencies of conspecific nest usurpation are most common where densities of Polistes metricus are high. Here nest usurpation occurs primarily in single-foundress colonies resulting in multiple-foundress colonies having significantly greater productivities than single-foundress colonies. This is not true at low densities. Conspecific pressures and not predation or parasitism provide an advantage to cooperating wasp foundresses in P. metricus.