I read a great article from the journal Cognition from 2009 but I am finally getting to it. The overall objective is to investigate if there are cognitive explanations for the development of supreme being beliefs. This is actually quite a large research area these days.
They started with the fact that kids often see teleological (purposeful) explanations for natural phenomenon. For example, “the rock is pointy so people won’t sit on it.” Obviously, this is not true; there is some natural erosion-related reason for the rock to be pointy. But kids, even through much of elementary school, make teleological assumptions about the world.
Adults don’t do this, right? This study examined whether there are conditions where they do. They found that when mental workload is high, time pressure is exerted, or when scientific knowledge is low. This is an OR not an AND. Even college science majors do it when in a rush. Alzheimer’s patients do it often, so apparently the teleological instinct sticks with us for our entire lives and scientific knowledge and effort suppresses it. But it’s there, ready to show itself when attention is low.
It wasn't a speed/accuracy tradeoff kind of thing because it didn't happen in a variety of control conditions. And some people made teleological assumptions even when they had plenty of time and knowledge (e.g. Creationism).
Why is it an adaptive cognitive heuristic to attribute teleological explanations as a default? I suppose that it is better to be safe than sorry. If there is a purposeful reason for something, guessing at the reason could help. But if there isn’t a purposeful reason, imagining one doesn’t really hurt in the short term. In the long term, it leads to things like religion and can degrade complex decision making processes. But we evolved before this was the case.