Darwinism doesn't perpetrate a perfect future, it just states reality as it is. Those who adapt survive--Not the strongest, not the smartest, but the most adaptable.
That's not exactly true. It IS true that species characterized by being capable of exploiting a broad range of circumstances as opposed to occupying a narrow niche have a better shot. But having characerstics in populations become more prevalent can be due to the environment rather than having some individuals be more adaptable.
The classic melanistic moth story of natural selection is an example (
http://www.millerandlevine.com/km/evol/Moths/moths.html" onclick="window.open(this.href);return false;). The population was predominately composed of individuals colored so as to blend with tree bark so that predators couldn't see them well. After the industrial revolution started, trees became blanketed with soot so that the "normal" moths stood out and the melanistic, or black, form of the moth became hard to see. The black moth came to dominate the population. Then when controls were put in place to reduce pollution and the soot problem receded, the "normal" moths became more common again.
Same kind of thing with beaks of finches (
http://www.pbs.org/wgbh/evolution/libra ... 16_01.html" onclick="window.open(this.href);return false;). During a period of drought selection favored bigger birds with heavier beaks because they were able to eat tougher seeds. But in a later wet period smaller birds were favored.
So it's not necessarily a matter of adaptability. It can be a matter of luck. It just so happens that prevailing condiitons favor certain individuals in the population and those individuals reproduce at a higher rate so their characteristics get expressed. But under a different set of conditions some other set of individuals may have "prevailed."