The Overclocked Genome

Abstract

The divergence between modern humans and archaic hominins such as Denisovans and Heidelbergensis is routinely presented as evidence for an evolutionary timescale spanning hundreds of thousands of years. This paper asks whether the number of substitutions arising on an archaic lineage can instead be accounted for by elevated paternal mutation input within a chronology derived from advanced ages of the patriarchs following the Flood that occurred just a few thousand years ago. Applying the paternal age dependence of the de novo mutation rate reported by Kong and colleagues (2012) to the patriarchal ages preserved in the Biblical text, I model a nine generation lineage descending from Shem and find that it accumulates approximately 29,747 de novo mutations, of which roughly 1,041 are classified as slightly deleterious but invisible to selection. Combined, this is approximately 98 percent of the figure of 31,389 that is frequently cited as the count of changes separating modern humans from archaic hominins. I then show that this figure, drawn from Pruefer and colleagues (2014), refers specifically to sites fixed on the modern human lineage while remaining ancestral in archaics, and is therefore neither a Denisovan branch quantity nor a measure of Denisovan diversity. I distinguish three quantities that are frequently merged in both creationist and evolutionary discussion, namely per generation mutation input, lineage divergence, and within population diversity, and I argue that a defensible young age model must aim its mechanism at the correct quantity. I further note that Denisovan and other archaic within population diversity is in fact extremely low, a result that favors a recently founded small population. I close by stating, in falsifiable terms, the objections the model must still answer.