False-color transmission electron micrograph of a field of whooping cough bacteria, Bordetella pertussis. A. Barry Dowsett/Science Source hide caption

itoggle caption A. Barry Dowsett/Science Source

This mouse egg (top) is being injected with genetic material from an adult cell to ultimately create an embryo — and, eventually, embryonic stem cells. The process has been difficult to do with human cells. James King-Holmes/Science Source hide caption

itoggle caption James King-Holmes/Science Source

In this colored transmission electron micrograph, an infected cell (reddish brown) releases a single Ebola virus (the blue hook). As it exits, the virus takes along part of the host cell's membrane (pink, center), too. That deters the host's immune defenses from recognizing the virus as foreign. London School of Hygiene & Tropical Medicine/Science Source hide caption

itoggle caption London School of Hygiene & Tropical Medicine/Science Source

I'm not trying to lead you astray. It's just that scientists are not skeptical enough about their mouse studies. iStockphoto hide caption

itoggle caption iStockphoto

An artist's illustration shows lung cancer cells lurking among healthy air sacs. David Mack/Science Source hide caption

itoggle caption David Mack/Science Source

The research team used yeast chromosome No. 3 as the model for their biochemical stitchery. Pins and white diamonds in the illustration represent "designer changes" not found in the usual No. 3; yellow stretches represent deletions. Lucy Reading-Ikkanda hide caption

itoggle caption Lucy Reading-Ikkanda

Your schnoz deserves more respect. epSos .de/Flickr hide caption

itoggle caption epSos .de/Flickr

A channel big enough to handle global shipping would require deep dredging throughout Lake Nicaragua, the largest source of fresh water in Central America. Esteban Felix/AP hide caption

itoggle caption Esteban Felix/AP

Until recently, finding characteristic stone and bone tools was the only way to trace the fate of the Clovis people, whose culture appeared in North America about 13,000 years ago. Sarah L. Anzick/Nature hide caption

itoggle caption Sarah L. Anzick/Nature

Clive Hamilton's new book Earthmasters. Courtesy of Yale University Press hide caption

itoggle caption Courtesy of Yale University Press

The Climate Casino by William Nordhaus looks at the economics and politics of global warming. Courtesy of Yale University Press hide caption

itoggle caption Courtesy of Yale University Press