  If evolution can be connected to the principle of least action, and if it is
depicted in evolution space versus time then it corresponds to the direction of
ultimate causation. As an organism evolves and follows a path of proximate
causation, if the vector is closely parallel to that of the ultimate causation
then the changes will confer desirable attributes which will lead to further
development. If however the variations do not occur in a direction close to the
of the ultimate causation vector the evolved organism will quickly die out.
This may be viewed as similar to Feynmans sum over all histories. Therefore,
the principle of least action gives a direction, but not a purpose, to
evolution. Taking the coevolution model of Lewontin, an equation of motion for
coevolution shows that it is the rate of evolutionary change that responds to
changes in the environment, in line with some evidence. In the face of widely
held views on mass extinctions because of climate change this gives some small
hope.
