What is sex? How did it originate? Why does it persist?

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I examine the definition, origin, and ubiquity of sex.  Perspectives change when fundamental assumptions are questioned.  Does self fertilization count as sex?  Why is genetic mixing considered the primary function of sex, despite the need to invoke group selection?  My goal is to write a definitive evolutionary history of sex.My working hypothesis is that production of gametes and fertilization both rejuvenate an organism.  I posit that sex is not primarily a genetic phenomenon, but rather an epigenetic one.  More specifically, sex slows down evolution by resetting molecules responsible for development, resetting them to their state in previous generations.  This provides a direct benefit to the individual organism insofar as development would eventually go awry without production of gametes and fertilization.  This working hypothesis may explain the origin of sex and why sex still persists.  Compare this with the current and long-lived paradigm for the ubiquity of sex, in which sex increases genetic variation amongst all descendants, thereby speeding up evolution, but is not necessarily advantageous to any individual.Our research entails devising theory, building mathematical models, and conducting empirical tests.  The theoretical work takes two tacks.  First, we try to explain why reset of developmental signals is associated with gamete formation and fertilization.  Why should this reset be inextricably tied to halving the number of chromosomes?  Second, we consider the term 'gene' to include signals that control development, even if these developmental signals may not be directly coded for by DNA.  We build mathematical models of how such generalized genes evolve, which we use to test whether presence of sex provides an advantage to populations and hence possibly explain why sex has persisted.  We empirically test whether reset of those molecular signals that regulate development are exclusively associated with meiosis and fertilization.