Question

Why is evolutionary change constrained by its past but impossible to predict?

Short answer

Evolution has no clear ulterior motive, so the evolutionary change constraint is impossible to predict.

Step-by-step solution

Evolutionary constrain

The evolutionary constrain are the limitation or biases on the outcome of adaptive evolution.All evolution is constrained.

Evolutionary change is impossible to predict

Pre-existing elements constrain the new structures and metabolic functions. Because evolution lacks a clear ulterior motivation, it is impossible to predict.

Moreover, the genetic variations occur randomly that why evolution is generally unpredictable. However, the observed recurring convergence of evolution leads to the occasional loss of pigmentation in living things.

Hence, evolutionary change constrained by its past is not possible to predict.