The neutral theory of evolution holds that “most variation at the molecular level does not affect fitness and, therefore, the evolutionary fate of genetic variation is best explained by stochastic [random] processes.”
However, what scientist Fanny Pouyet and colleagues from the Group of Laurent Excoffier at the SIB Swiss Institute of Bioinformatics and University of Bern recently discovered, is that 95% of our genome actually seems to be affected by selection and other genetic biases and that markers previously thought to be neutral appear to provide skewed estimates. Their study, published in eLife, calls for the re-examination of a plethora of results and provides the tools and recommendations to correct such issues in the future.
Models used to reconstruct the history of a species or to discover how populations are related to one another rely on a key assumption: that the genome regions under scrutiny are made of “neutral” snippets of DNA, i.e. parts that have evolved randomly rather than being selected for or against. But these regions might actually not be as neutral as previously thought, according to a recent finding by scientists at SIB and the University of Bern: “What we find is that less than 5% of the human genome can actually be considered as “neutral”,” says Fanny Pouyet, lead author of the study. “This is a striking finding: it means that 95% of the genome is indirectly influenced by functional sites, which themselves represent only 10% to 15% of the genome,” she concludes. These functional sites encompass both genes and regions involved in gene regulation. Paper. (open access) – Fanny Pouyet, Simon Aeschbacher, Alexandre Thiéry, Laurent Excoffier. Background selection and biased gene conversion affect more than 95% of the human genome and bias demographic inferences. eLife, 2018; 7 DOI: 10.7554/eLife.36317
Perhaps the most reasonable conclusion is that all of Darwinism is in a mess similar to that of speciation.
See also: Heads up! Neutral theory of evolution
Commenter nails the problem with neutral theory of evolution