The point cannot be just survival, nor even survival in numbers. Survival is just as well achieved by much less ambitions creatures which go in for s… - Mary Midgley

Creatures really have divergent and conflicting desires. Their distinct motives are not (usually) wishes for survival or for means-to-survival, but for various particular things to be done and obtained while surviving. And these can always conflict. Motivation is fundamentally plural. It must be so because, in evolution, all sorts of contingincies and needs arise, calling for all sorts of different responses. An obsessive creature, constantly dominated by one kind of motive, would not survive.

The contrary, literalist campaign within Christianity is actually quite recent. It developed among more or less extreme Protestants after the Reformation – largely indeed in the last century in the US. It was consciously designed as a competitor with science, providing equal certainty by comparable methods. It is thus a political phenomenon, acting in some ways like a cargo cult. It has enabled relatively poor and powerless people to use their Bibles (which the Protestant Reformers had provided) to shape a rival myth of their own. They see this as an alternative to the materialist glorification of science and technology which they have perceived – with some reason – as the oppressive creed of those in power.

But understanding and explaining motives does not compromise freedom; nor does even predicting acts necessarily do so. A person committed to a political cause may vote predictably, and intelligibly in an election. He does not vote less freely than someone that flips a coin at the last minute. So if we find comparison with animals any help in understanding motives, it will not mean that conduct is not free. And since animals are not (as Descartes supposed) automata, the issue of freedom does not make comparing man with any other species and downgrading irrelevance.