It is evolution, and it speeds up with higher populations. As for natural selection, consider that only small changes in allele frequencies add up quickly through the generations. Also, sexual selection is very much a force.

http://www.scribd.com/doc/33322719/Cochran-Gregory-10-000-ye... http://www.nytimes.com/2007/12/11/science/11gene.html http://www.wired.com/wiredscience/2007/12/humans-evolving/