How Do Species Evolve?
When foreign ants trespass on carpenter ant territories in Borneo, the worker ants living there take extreme action. They blow themselves up, fatally miring the intruders in sticky, yellow goo (pictured here in February 2006). How is this suicide favored by evolution? Ant workers are sterile. Their self-destruction helps queen and colony produce the next generation of ants that can reproduce. For these worker ants, the sacrifice is apparently worthwhile, says University of Utah ecologist Dinah Davidson.
—Photograph by Dinah Davidson
