Farming helped fuel the rise of civilizations, but it may also have given us less robust bones. Leemage/UIG via Getty Images hide caption

itoggle caption Leemage/UIG via Getty Images

An inside view of this fossil Pseudodon shell shows that the hole made by Homo erectus is exactly at the spot where the muscle attached to the shell. Poking at that spot would force the shell open. Henk Caspers/Naturalis Leiden/The Netherlands hide caption

itoggle caption Henk Caspers/Naturalis Leiden/The Netherlands

This is a re-creation of a color plate from Interaction of Color, by Josef Albers. The two X's are are exactly the same — it's the different backgrounds that make them look like very different colors. Source: Josef Albers Interaction of Color hide caption

itoggle caption Source: Josef Albers Interaction of Color

Stringy particles of Ebola virus (blue) bud from a chronically infected cell (yellow-green) in this colorized, scanning electron micrograph. NIAID/Science Source hide caption

itoggle caption NIAID/Science Source

A rogues gallery of the viruses (left to right) that cause MERS, SARS, and influenza. Niaid; 3D4Medical; Niaid/Science Source hide caption

itoggle caption Niaid; 3D4Medical; Niaid/Science Source

The cruise ship Carnival Magic floats behind a catamaran off Cozumel, Mexico on Oct. 17. The ship skipped a planned stop there Friday, the cruise line says, after Mexican authorities delayed granting permission to dock. Reuters/Landov hide caption

itoggle caption Reuters/Landov

Avian influenza, or bird flu, causes an infectious and contagious respiratory disease. In the lab, several scientists have made the H5N1 strain more contagious, a controversial line of research. James Cavallini/ScienceSource hide caption

itoggle caption James Cavallini/ScienceSource