competition

it is said (or Darwin said) that the law of nature is survival of the fittest. In plain language this means that the weaker ones are to be weeded out and replaced by superior ones. This system places premium on the stronger, faster and better. As this process continues, the system as a whole becomes better and better. Is this really so?. Is there no place for weaker, slower or ordinary. Isnt it that for someone to prove its strenght requires weak ?, and someone who has been proved strong today maybe be weak tommorrow in face of someone else being stronger. further, if all want to be strong, then it will increase competition on unhealthy lines. Wonder, where this process will end?