de novo gene birth as an inevitable consequence of adaptive evolution

Phylostratigraphy suggests that new genes are continually born $\textit{de novo}$ from non-genic sequences. The genes that persist found new lineages, contributing to the adaptive evolution of organisms. While recent evidence supports the view that $\textit{de novo}$\denovo gene birth is frequent and widespread, the mechanisms underlying this process are yet to be discovered. Here we hypothesize and examine a potential general mechanism of gene birth driven by the accumulation of beneficial mutations at non-genic loci. To demonstrate this possibility, we model this mechanism, within the boundaries set by current knowledge on mutation effects. Estimates from this simple analysis are in line with observations of recurrent and extensive gene birth in genomics studies. Thus, we propose that rather than being inactive and silent, non-genic regions are likely to be dynamic storehouses of potential genes.