What does "jeux d'esprit" mean? Failed to find it in OneLook

Context:

Darwin explained, 'natural selection is daily and hourly scrutinis-
ing, throughout the world, every variation, even the slightest;
rejecting that which is bad, preserving and adding up all that is
good; silently and insensibly working, whenever and wherever
opportunity offers, at the improvement of each organic being'. If a
wild animal habitually performs some useless activity, natural
selection will favour rival individuals who devote the time and
energy, instead, to surviving and reproducing. Nature cannot afford
frivolous jeux d'esprit. Ruthless utilitarianism trumps, even if it
doesn't always seem that way.