That is the nature of the framework of existence that everything is in. All matter, all atoms, all forms of energy, everything obeys laws. Those laws, through an evolutionary mechanism, would require that they be setup in such a way that over time benefits created by the random action of other mechanism at work (genetic drift, mutations, etc.) be weighed against other ones, resulting in a better adapted being for its environment.
In a sense it is. It is called survival of the fittest. Those best adapted to the environment survive those that don't become extinct.
What may seem to be a totally neutral mutation today, may eventually become a positive trait should the environment change or it could be come a detriment for the same reason. There is no purpose.
There is no better love between 2 people than mutual respect for each other WT Young, 2002
Who gave anyone the authority to call me an authority on anything. WT Young, 1969
™ Version 4.2