There could be any number of incentives, i.e. health benefits. Apes, just like birds, builds nests and this "ritualistic" behaviour could be seen as an extensio

There could be any number of incentives, i.e. health benefits. Apes, just like birds, builds nests and this "ritualistic" behaviour could be seen as an extension of cleaning. Being this calculated about this seemingly arduous task obviously hints at something more advanced than cleaning (i.e. spiritual reasons), I'm just trying to bridge the gap between "calculated rituals" and "random rituals".