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Title: What's good for the goose is good for the gosling? Evolutionary theory, parent-offspring conflict and genetic disorders
Abstract: Conflict is ever-present in nature, serving as an essential driver of adaptation. In this dissertation, I examine both intra- and interpersonal conflicts as they occur at the genetic level. Specifically, what happens when, within a single individual, a gene inherited from one parent has a different optimal strategy than a gene inherited from the other parent? This unique circumstance leads to a phenomenon known as genomic imprinting, whereby variation in the expression of a gene depends on the sex of the parent from whom the gene was inherited.
This dissertation will explore the impact of genetic conflict on our human evolutionary trajectory in three ways. First, I consider the natural history of Prader-Willi syndrome, a disorder that results from lack of paternally derived expression on chromosome 15. This work was done in collaboration with a Canadian endocrinology clinic specializing in the treatment of children and young adults with Prader-Willi syndrome. While this disorder has been examined from an evolutionary perspective in the past, new clinical guidelines for the progression of Prader-Willi syndrome necessitated a reinterpretation of evolutionary conclusions, specifically regarding timing of the onset of feeding-related behaviors.
Next, I go on to examine psychological symptoms in imprinting disorders. Here I focus on differences in attentional demands between individuals with Prader-Willi syndrome and those with Angelman syndrome, a disorder resulting from a lack of maternally derived expression at the same locus on chromosome 15. This work was done in collaboration with faculty and students from the Evolutionary Psychology Lab at Harvard University, who were pursuing a theory related to the evolution of music as an honest signal of parental attentional investment. Here we use both experimental and survey data to collect and compare various psychological and physiological measures relating to attention, responses to music, and sleep behaviors, from both individuals with these disorders and their parents. This offers a unique look at how imprinting impacts both the personal experience and family dynamics of a parent-offspring dyad.
In my final chapter, I focus on ways in which genomic conflict is implicated in the evolution of human childhood transitions. I pull from a broad spectrum of medical and genetic data to present evidence for the theory that maternal/paternal conflicts have been involved in the division of human childhood into three distinct phases: a nurseling phase from birth to weaning; a weanling phase from weaning to adrenarche; and a juvenile phase from adrenarche to gonadarche. This is in contrast to other apes, for whom weaning and adrenarche occur simultaneously. I argue that the breakdown of these events in human maturation is a reflection of the maternal preference for a compressed weaning period. I also review existing data on the transition to sexual maturation from the kin conflict perspective.
Finally, I discuss the relationship between evolutionary biology and clinical science, emphasizing ways in which collaboration between biologists and physicians enhances both fields. Together, this dissertation represents an application of evolutionary theory to questions of human health and wellbeing.
Committee: David Haig (Advisor), Robin Hopkins, Max Krasnow and Naomi Pierce