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# Hardy-Weinberg law

/hahr"dee wuyn"berrg/, Genetics.
a principle stating that in an infinitely large, randomly mating population in which selection, migration, and mutation do not occur, the frequencies of alleles and genotypes do not change from generation to generation.
Also called binomial law, Hardy-Weinberg distribution.
[1945-50; named after English mathematician G. H. HARDY and German physician Wilhelm Weinberg (1862-1937), who independently formulated it]

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Equation that describes genetic balance within a population.

It may be stated as follows: In a large, random-mating population, the proportion of dominant and recessive genes (see dominance and recessiveness) tends to remain constant from generation to generation unless outside forces act to change it. Forces that can disturb this natural balance are selection, mutation, gene flow, and natural selection. Certain gene-controlled traits are selected for or against by the partners involved. The law is used to determine whether the number of harmful mutations in a population is increasing.

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an algebraic equation that describes the genetic equilibrium within a population. It was discovered independently in 1908 by Wilhelm Weinberg, a German physician, and Godfrey Harold Hardy (Hardy, Godfrey Harold), a British mathematician.

The science of population genetics is based on this principle, which may be stated as follows: in a large, random-mating population, the proportion of dominant and recessive genes present tends to remain constant from generation to generation unless outside forces act to change it. In such a way even the rarest forms of genes, which one would assume would disappear, are preserved. The outside forces that can disrupt this natural equilibrium are selection, mutation, and migration. The discovery of this law was especially significant in affirming natural selection as the primary mechanism of evolution. If the proportions of gene forms in a population do not change, the rate of evolution will be zero. Individual variations occur because of the various genetic combinations that result from random mating of individuals, but nonrandom, or selective, mating must occur for natural selection to take place. Certain gene-controlled traits are selected for or selected against by the partners involved. Over a long period of time, this selective pressure will change the frequency of appearance of certain gene forms, and the traits they control will become commoner or rarer in the population.

Medical geneticists can use the Hardy-Weinberg law to calculate the probability of human matings that may result in defective offspring. The law is also useful in determining whether the number of harmful mutations in a population is increasing as a result of radiation from industrial processes, medical techniques, and fallout.

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Universalium. 2010.

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