In "The Life of the Bee" by Maeterlinck (edited in 1901!), one can read that the research of a Carter revealed that such phenomena as the free will, desire and free choice manifest itself in creatures so primeval as the slime molds. (I have paraphrased this fragment from a Polish translation from French).
Does, perhaps, anybody know something about the Carter and his/her research, papers etc? They date from the XiXth century. It looks as if the computational skills of slime molds have been known for much longer than one could expect.