Biologists like Robert Full at the University of California, Berkeley, have shown over the last few decades how animals like geckos, cockroaches and squirrels physically move and how their bodies and limbs help them in sticky situations — all of which have been applied to making more agile robots. But now they are tackling a harder problem: How do animals decide whether or not to take a leap? How do they assess their biomechanical abilities to know whether they can stick the landing?