The tidy web on the left is the work of a 17-day-old European house spider, less than 5 percent of the way through its average life span of one year. When a middle-aged (188-day-old) house spider took up the same task, however, it produced the more irregular, holey web on the right.

One way to understand how aging affects humans is to examine the same mechanism in organisms with simpler nervous systems—and shorter life spans. Mylène Anotaux of Nancy University, the researcher who took these images, evaluated spiders' webs over the course of their lives, using criteria such as the regularity of the web structure and the presence of holes. Her conclusion, which Anotaux will present on July 2 at the Society for Experimental Biology Annual Conference, indicates that spiders' weaving skills deteriorate as they age.

A declining central nervous system may be causing this breakdown. If so, scientists could look for other examples of how aging affects other animals.

—Sophie Bushwick