Genetic Determinism - Origins

Origins

Genetic determinism, which identifies the gene as the biological source of morphology and instinct, can be traced back to Austrian theorist August Weismann, who proposed in the 1890s that the key actors in the struggle for survival are not organisms but their genes, which he called determinants. While Darwin’s concept of natural selection was intended to apply to whole organisms, Weismann modified Darwin's idea according to a process he called "germinal selection." Since the fittest determinants would be whichever ones correlate to the most useful phenotypic traits, germinal selection would result in the fittest organisms surviving and reproducing. Weismann referred to the chemical carrier of these determinants as the germ plasm, now known to be DNA.

Weismann’s view was founded on the belief that biological inheritance is inconceivable except by way of germ plasm from parents to offspring. As Stephen Jay Gould pointed out, this belief was not based on empirical observation. "We accept it," wrote Weismann, "not because we are able to demonstrate the process in detail... but simply because we must, because it is the only possible explanation that we can conceive." On the assumption that behavior cannot affect genes, Weismann argued that only genetic mutation, not adaptations on the part of a struggling organism, could significantly alter the developmental patterns inherited by progeny. Though contrary to Darwin's view, Weismann's belief that determinants shape the body, and never vice versa, has long been known as the central dogma of modern biology.