For any living system that has had sufficient time to adapt to its environment, it can generally be assumed that the system has reached (or nearly reached) a local optimum for that environment, for the same reason that if you let a marble roll around on a surface for a long enough time, you can generally assume that it will come to rest at a local minimum. Of course, just as the local minimum of the marble is defined by the surface, the local optimum in the evolution of a trait is defined relative to the current environment. If the environment is rapidly changing, then you cannot assume near-optimality, just like you cannot assume the marble will come to rest on a constantly undulating surface.
> For any living system that has had sufficient time to adapt to its environment, it can generally be assumed that the system has reached a local optimum for that environment
Really? Think about humans, in our current environment, can you not think of any adaptations to our bodies that would improve us as a species? If in 100 million years our environment doesn't change at all (hypothetical) will we not evolve any more?
Humans have not been in an unchanging environment for the past several thousands years at least, and by their nature (constant technological development, etc.) are unlikely to be so ever again.
Hence I said hypothetical, I wasn't predicting the future, just the fact that were we to be in an unchained environment the chances are we would evolve to become improved, rather than stay the same.
