[unspun]

What do you suppose "survival of the fittest" is supposed to be fit?

It is all supposed to be about the purpose of adaptation being for better survival of the conditions of life on Earth.

(Kindly suggest you don't beg the question by suggesting a disctintion of whether a purpose is "ultimate" or "destiny" or not.)

[unspun]

disctintion = distinction

[Doctor Stochastic]

Then you haven't understood at all. Survival of the fittest is an ex-post concept, not an ex-ante. (I would have called it survival of the adequate, but my suggestion came too late.) You should read some biology texts.

Mutations (and other genetic happenings) propose and selection disposes. There's no teleology, just survival. Sometimes (as in the Toba erruption), location is important. Sometimes disease resistance is important. Sometimes naturally curly hair is important.