Now, USC researchers want to add a new rule called “selectively advantageous instability (SAI),” which explores how instability can actually benefit a cell and a cellular organism. The flipside of this “rule” is that SAI can also be a key factor to things like disease and aging, so understanding this process could aid in exploration of those biological processes. Across the sciences, rules and laws help us make sense of the world around us, whether applied to cosmic scales or subatomic ones. However, in the biological world, things are a bit more complicated. Another “law,” known as Bergmann’s rule, states that species of a broadly distributed clade tend to be larger in colder climates and smaller in warmer ones (though of course, as with most biological rules, exceptions apply ).