Evolving Darwinian Evolution

Darwin may have missed a key part of the evolutionary selection process. In the paper below,

Evolving Darwinian Evolution

Preselection Theory and the Selective Advantage of a High Male to Female Mutation Rate Ratio:

Testing Mutations Before Spending a Life

I propose a theory, Mutation Preselection Theory, that expands on Darwin’s Natural Selection Theory by adding a second stage of selection, between each cycle of life. The theory explains why most mutations happen in male rather than female gametes, because deleterious mutations in the male germline can be tested and selected against in the competition among sperm, showing that evolution found a way to bound the randomness of mutations and select among them before those mutations make their way into a fertilized egg.

A fundamental tenet of Darwin’s natural selection theory of evolution is that mutations are random. Yet, if evolution had stumbled upon a more efficient way of testing mutations than randomness, natural selection would have selected for it. Here, I argue that indeed it has –perhaps Darwin’s greatest omission--, and put forth Mutation Preselection Theory, hypothesizing that, in species where sperm compete with each other whilst a smaller number of ova are available for fertilization, a mutation rate that is significantly higher in males than in females would have been selected for, because many deleterious mutations in sperm could be selected against by selecting for the winning sperm, whilst deleterious mutations in females would lead to lower fitness of the resulting embryo, with a much higher cost. This is indeed the case: the male to female mutation rate ratio is much higher than 1, varying from 2.4 to 20 in mammals, fish and plants. The theory makes a wide variety of additional predictions and has significant explanatory power over a large array of previously unexplained biological phenomena. It explains why species with longer embryo to adult development time, in which the cost of a deleterious mutation might take longer to select against and thus incur a greater cost for its family, have a higher male to female mutation rate: the male to female mutation rate ratio is higher in humans, in which deleterious mutations could take decades of development to impact fitness, and is lower in monotremes and hedgehogs, where gestation is only 30-40 days and adulthood is reached after only 5-6 months. The theory also explains the finding that sperm express many genes, contrary to the widespread belief that its compact chromatin structure prevents gene expression. A further prediction of the theory is that the lifecycle of sperm has evolved to test the viability of a wide variety of genes, and that sperm fitness, defined as the probability that a sperm cell will fertilize an egg, correlates with the fitness of the resulting individual. As predicted, human intelligence correlates with sperm quality. The theory may explain the Cambrian explosion, the high rate of viability of embryos, findings about the evolution of chromosomes expressed only in females, and provide a role for the vast non-coding regions of the genome. I propose new definitions for male and female, and a novel explanation for sex itself.

Read the paper here.

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