about 7 percent of human genes are undergoing rapid, relatively recent evolution. Even with these changes, however, human DNA remains more than 99 percent identical...and a genetic predisposition to basic math ability turns out to be mythical.
Most of the significant evolutionary pressures concern diseases, both inherited and acquired. Even the dumbest idiot is usually provided some sort of charity/hand-out in most societies. Intelligence needn’t necessarily be a force for evolution as much as the other factors are, in modern human beings. An exception to this would be among small groups of people living nomadic lifestyles, where the size of the group is too small for members to be able to compensate for the shortcomings of other members.
The area of the human genome that is contained within genes is a fraction of the total DNA. Genes themselves are comprised of promoters, enhancers, upstream and downstream regulatory sequences, coding and non-coding sections of the message. The coding parts, that are the blueprint for the proteins or RNAs, are themselves small parts of the entire gene.
I'm not sure if the researchers here are using the word "gene" in the context of the entire gene with all the regulatory sequences included, or just the part of the gene that codes for a product (which is also a correct use of the word).
Either way, when the researchers state that 7 percent of the genes are undergoing rapid evolution, they are talking about a very small fraction of the entire human genome.
Genes are found along DNA strands. 7% of genes could be rapidly changing with little change in aggregate DNA content. Besides, not all your DNA is composed of genes ~