Complex sentence: The capacity to put more weight on negative entities than positive ones likely evolved for an important reason: to of humanity is has been our most important survival skill to be able to stay away from or dodge danger.
Split into simpler sentences: The capacity to put more weight on negative entities than positive ones likely evolved for an important reason: to keep us out of harm's way. From the beginning of humanity is has been our most important survival skill to be able to stay away from or dodge danger.