New limits to functional portion of human #genome reported: Work suggests at least 75 percent of the genome is junk DNA — ScienceDaily
▻https://www.sciencedaily.com/releases/2017/07/170714140234.htm
The functional portion of the genome is described as that which has a selected-effect function, that is, a function that arose through and is maintained by natural selection. Protein-coding genes, RNA-specifying genes and DNA receptors are examples of selected-effect functions. In his model, only functional portions of the genome can be damaged by deleterious mutations; mutations in nonfunctional portions are neutral since functionless parts can be neither damaged nor improved.
Because of deleterious #mutations, each couple in each #generation must produce slightly more children than two to maintain a constant population size. Over the past 200,000 years, replacement-level fertility rates have ranged from 2.1 to 3.0 children per couple, he said, noting that global population remained remarkably stable until the beginning of the 19th century, when decreased mortality in newborns resulted in fertility rates exceeding replacement levels.
If 80 percent of the genome were functional, unrealistically high birth rates would be required to sustain the population even if the deleterious mutation rate were at the low end of estimates, Graur found.