cues that the deceased is in the vicinity, and rumination over the circumstances of death [ 1–3 ]. The symptoms of grief are among the most intensely stressful experienced by humans, and, consonant with this, are likely to be detrimental to biological fitness [ 4–6 ]. From an evolutionary perspective, grief is an especially puzzling phenomenon—ceteris paribus, we should expect natural selection to minimize or eliminate responses that disrupt the individual’s ability to address current challenges and opportunities, and that entail direct somatic costs. Many investigators have sought to make sense of the symptoms of grief (most notably [ 7–10 ]). From an evolutionary perspective, these explanations largely fall into one of two categories. The first group of theories is ‘by-product’ accounts. According to one version of the by-product account, grief in the context of death is an unavoidable by-product of a more common separation response, a response that would have aided reunification (which was adaptive) in our ancestral environment, but which has always been fruitless (and thus maladaptive) in the context of death [ 7 ]. Just as some non-human animals (e.g. zebra finches [ 12 ]), vocalize their distress when separated and engage in searching behavior that adaptively aids reunification, humans engage in searching—at a variety of levels of consciousness—for a loved one when circumstances suggest that the beloved is lost. We term this version ‘the reunion account’ because in the context of separation short of death, searching is adaptive. In this account, the costs involved in grief are thought to be outweighed by the benefits conferred by separation responses. While the presence of these responses in the case of death simply reflect constraints on optimality—separation is such a powerful elicitor of the responses that it leads to distress and searching despite awareness of the impossibility of reunion. In other related theories, grief is viewed as a by-product of the e