selection pressures should favor genotypes that support a range of phenotypes in response to environmental conditions because this flexibility would be beneficial from the perspective of survival of the species. However, biological sensitivity to context has the potential for both positive effects under more highly supportive environmental conditions and negative effects in the presence of more negative environmental conditions. This theory has been most fully developed and discussed in the context of stress reactivity (Boyce & Ellis 2005), where it has been demonstrated that highly reactive children show disproportionate rates of morbidity when raised in adverse environments, but particularly low rates when raised in low-stress, highly supportive environments (Ellis et al. 2005). In these studies, high reactivity was defined by response to different laboratory challenges, and the authors noted that the underlying cellular mechanisms that would produce such responses are currently unknown, though genetic factors are likely to play a role (Ellis & Boyce 2008).
