That cabbage that you see in the produce aisle? It's smarter than you think. A new paper published in the most recent issue of Current Biology says that not only can they can tell time, but the clock also plays a key role in their defense mechanism against pests. Janet Braam, a professor of cell biology at Rice University in Texas that conducted the study, says that the secret lies in how the cabbage's defense syncs up with its circadian rhythm. The rhythm itself is a type of biological clock that refreshes every 24 hours.