Notional

In what way does having different inherent personalities contribute for the survival and prosperity of humans as a species, throughout the process(right term?) of evolution? As I understand personality is a combination of nature and nurture, but I'm referring more to the nature side. Also, bear in mind, nature also influences how we respond to the nurture part. So the same factors, will influence the nurture aspect of personality-building differently. Surely, specific kinds of personality will be more useful to survive and procreate, so shouldn't that have funneled down throughout human evolution? Just as we look so similar physically, shouldn't we also be just as similar personality-wise? I suspect I may be able to answer this, but I want to read what you have to say. I know only that I know nothing.