They have also been shown to (probably) play for no purpose at all: https://www.sciencedirect.com/science/article/pii/S0003347222002366 https://www.sciencedirec

They have also been shown to (probably) play for no purpose at all: https://www.sciencedirect.com/science/article/pii/S0003347222002366 https://www.sciencedirect.com/science/article/pii/S000334722...