Hard and soft heredity

Hard heredity consists in the transfer of the predispositions for individual traits from one generation to the next in unaltered form, without any effect on the other predispositions present in a particular individual and the effects of the external environment. In contrast, soft heredity assumes that predispositions can change from one generation to the next under the effect of the other predispositions present in a given individual and through the effect of the external environment. The Lamarckist theory of evolution and the later Darwin’s theory of evolution are based on the concept of soft heredity of predispositions; in contrast, the Neodarwinist theory of evolution, i.e. the main direction of the theory of evolutionary biology developed roughly from the 1930s and thus including the knowledge of Mendelian genetics, is based on the concepts of hard heredity.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more