The mechanisms of the possible biological alterations in the human population as a result of population control are discussed. Population control is distinguished from population limitation by defining it as actual genetic alteration through manipulation of fertilization. Population limitation such as the use of contraceptive methods is aimed at simply reducing the size of the population by changing reproductive behavioral patterns. Major avenues of population control include the freezing of semen for artificial insemination, which causes biochemical changes in the sperm cells and reduces spermatozoa viability in the female reproductive tract. Artifical fertilizations in infertile couples and prezygotic selection are other actions that can produce genetic alterations in the species. It is concluded that both deliberate and inadvertent changes in the modes of biological selection as a result of population control and limitation will alter the genetic characteristics of the human population, mainly by reducing genetic variability. These possibilities should be considered and watched carefully in population research.