belief in evolution not necessarily an evolutionary advantage

While acknowledging your right to disagree, for the present purpose I'm going to assume that the ‘theory of evolution’ (really more of an established principle) is essentially correct, along with all of the usual corollaries.

However, it does not follow that holding this view, however orthodox and realistically unassailable it may be, confers any evolutionary advantage whatsoever upon those who hold it. In fact the advantage, as measured by fecundity, may belong to those who hold another view, for example that humans have existed in our present form since the beginning of time, a view that approximately one third of Americans espouse. (Pew Research via Reuters)

While there are practical limits on how far one's internal model of the world may diverge from reality without negative repercussions upon one's chances for contributing to the gene pool of the future, social cohesion probably matters more than accuracy in something as esoteric as the origin of the human species. If access to resources depends in any tangible way upon echoing the views of those around you, however erroneous, voicing disagreement is likely to prove counterproductive, in terms of natural selection, even when your view is correct and theirs is not – perhaps especially then.

Nor should there be anything surprising about this. Science is a relatively young phenomenon. For most of the time since the emergence of humanity, we have dealt with our own unknown origins by telling stories, frequently quite fanciful stories involving magical beings, also frequently transforming those stories into dogma as some groups became dominant and others subservient. The need for some explanation, even if a vacuous one, might be considered a defining characteristic of the human species, as distinguished from chimps, for example, who lack complex language and presumably therefore also lack the need for explanations regarding questions they lack the capacity to pose, much less to contemplate at length.

And so we still do, traffic in stories that is. For most of us, most of what we know is composed, not of data and analysis, but of stories, sometimes based on data and analysis, more often not, or at least not directly so. Even so, the majority of us have had enough exposure to science to recognize reliable methods and reasonable conclusions, and make use of that general familiarity in filtering the stories to which we are exposed.

The lingering question is whether we should be concerned over higher rates of childbirth among people whose story filters are less well developed. Is there a risk of resultant devolution? Perhaps, if it were to persist for another few thousand years, but cultural evolution is happening far more quickly and there are far more pressing issues to worry about. We do, however, need to continue to put effort into bridging the gap between scientific methods and popular beliefs, working to improve everyone's story filters.