Due to altriciality and the importance of embodied capital, children’s fitness is contingent on parental investment. Injury suffered by a parent therefore degrades the parent’s fitness both by constraining reproduction and by diminishing the fitness of existing offspring. Due to the latter added cost, compared to non-parents, parents should be more cautious in hazardous situations, including potentially agonistic interactions. Prior research indicates that relative formidability is conceptualized in terms of size and strength. As erroneous under-estimation of a foe’s formidability heightens the risk of injury, parents should therefore conceptualize a potential antagonist as larger, stronger, and of more sinister intent than should non-parents; secondarily, the presence of one’s vulnerable children should exacerbate this pattern. We tested these predictions in the U.S. using reactions to an evocative vignette, administered via the Internet (Study 1), and in-person assessments of the facial photograph of a purported criminal, collected on the streets of Southern California (Study 2). As predicted, parents envisioned a potential antagonist to be more formidable than did non-parents. Significant differences between parents with children and non-parents without children in the threat that the foe was thought to pose (Study 1) were fully mediated by increases in estimated physical formidability
