Postpartum mood disorders develop shortly after childbirth in a significant proportion of women and have severe effects. Two evolutionary explanations are currently available. The first is that poor postpartum mental health is a consequence of an evolutionary trade-off – a compromise of neurological changes in the maternal brain during pregnancy which, on the one hand, maintain pregnancy, and on the other, increase the likelihood for postpartum women to develop psychopathology. The second explanation is that poor postpartum mental health is a (...) disease of civilization. This theoretical paper demonstrates that both explanations ignore the crucial event of childbirth. I elaborate on environmental features of childbirth, a physiological process that is substantially different in the current versus evolutionary childbirth and postpartum setting, and argue that maternal brain neuroplasticity and biochemical alterations are not an evolutionary trade-off, but an adaptation. Additionally, the incidents of poor postpartum mental health are better viewed as a maladaptation of the typical modern environments – an evolutionary mismatch. Thus, the potential to suffer from poor mental health in postpartum is an external, contingent happening, dependent on contemporary childbirth and postpartum environments, and not due to any essential property women possess as a result of evolutionary compromise. In fact, women are probably adapted to feel like superwomen right after birth, a state of mind that is an aid in adapting to motherhood. Distinguishing between evolutionary concepts in the context of pregnancy, birth, and motherhood is vital for developing more accurate preventions and interventions. (shrink)

Mismatch is a prominent concept in evolutionary medicine and a number of philosophers have published analyses of this concept. The word ‘mismatch’ has been used in a diversity of ways across a range of sciences, leading these authors to regard it as a vague concept in need of philosophical clarification. Here, in contrast, we concentrate on the use of mismatch in modelling and experimentation in evolutionary medicine. This reveals a rigorous theory of mismatch within which the term ‘mismatch’ is indeed (...) used in several ways, not because it is ill-defined but because different forms of mismatch are.distinguished within the theory. Contemporary evolutionary medicine has unified the idea of ‘evolutionary mismatch’, derived from the older idea of ‘adaptive lag’ in evolution, with ideas about mismatch in development and physiology derived from the Developmental Origins of Health and Disease (DOHaD) paradigm. A number of publications in evolutionary medicine have tried to make this theoretical framework explicit. We build on these to present the theory in as simple and general a form as possible. We introduce terminology, largely drawn from the existing literature, to distinguish the different forms of mismatch. This integrative theory of mismatch captures how organisms track environments across space and time on multiple scales in order to maintain an adaptive match to the environment, and how failures of adaptive tracking lead to disease. Mismatch is a productive organising concept within this theory which helps researchers articulate how physiology, development and evolution interact with one another and with environmental change to explain health outcomes. (shrink)