In the doctrine of determinism, there is no purpose. Things cause other things, and that's that. There is no inherent goal or future purpose to anything. Developmental change actually has no intrinsic purpose. It is an error to think that it does.
Teleology is a tempting intuition.
It gives satisfying meaning to a developmental pattern. The end of the process stands as the meaning of all the earlier parts of the process. An acorn becomes an oak because that is its destiny. We want to believe there is some purpose or meaning to the process, defined by its end point. This temptation seduced Hegel, leading to his philosophy of the super-personal spirit, or Geist, the future wholeness towards which history is drawn.