Researchers describe a new evolutionary theory: The Black Queen Hypothesis

Bacteria belonging to the genus Prochlorococcus are some of the wimpiest in the world. Left to their own devices, these microorganisms have an exceedingly difficult time just staying alive — which seems counterintuitive, given that they're also the most abundant photosynthesizing organisms on Earth. »3/28/12 5:00pm3/28/12 5:00pm