Night waking among breastfeeding mothers and infants Conflict , congruence or both ?

Thank you for the privilege of commenting on David Haig’s interesting and timely proposal ‘Troubled sleep: night waking, breastfeeding, and parent– offspring conflict’. Haig’s main hypothesis, written quite superbly, is a simple one. He argues that frequent night waking to breastfeed poses a significant challenge to mothers sleep and is the infant’s way of prolonging lactational amenorrhea. Specifically, this has the effect of augmenting the inter-birth interval (IBI) essentially forestalling the infant from having to compete with a sibling for maternal resources. The author worries and makes the point several times that those like myself conducting evolutionary-based work on infant sleep conflates fitness and health. A central part of his thesis is that two welldocumented genetic (partial or whole) deletions on Chromosome 15, associated with Prader Willi and Angleman Syndromes are the basis for proving a genomic conflict existing between a paternal gene (promoting infant wakening) and the maternal gene (on Chromosome 15) promoting infant sleep consolidation. I find his essay very thought-provoking, especially how he perceives my own and others theoretical orientations who specifically investigate (from an evolutionary point of view) contemporary infant feeding and sleeping arrangements in western industrialized societies. I certainly benefited from his critique and was moved forward in my thinking by the theory he proposes. But I do not think that this perspective or its future application will necessarily trump what I think empirical research has demonstrated are critical factors, functions and interdependent physiological processes likely governed by multiple gene sets, that, I argue, likely serve as a better explanation of infant night wakening, and, thus, offer a both professionals and parents alike a better chance to manage and understand night waking in all of its diverse forms. And what I mean by all their ‘diverse forms’ is that after observing hundreds of the circumstances by response to target article 40