Walking in the woods in the UK would more than likely reveal ash trees marked with colored paint, flagged for felling because of the presence of the lethal “ash dieback” fungus, Hymenoscyphus fraxineus. Having a system of identifying and sorting healthy from diseased trees seems to work well for managing timbered areas – the tagging is specific and tailored to the problem at hand.
The process is not dissimilar to what happens in human cells. Throughout the animal kingdom, a way of marking unneeded...