Biological Determinism

The term biological determinism refers to claims that most human characteristics—physical, mental, and personality based—are determined at conception by hereditary factors passed from parent to offspring during reproduction. Of course, all human traits are ultimately based in the material nature of our being organisms (e.g., memorizing a poem involves changing molecular configurations at synapses, where nerve cells interact), but the term biological determinism has come to imply a rigid causation largely unaffected by environmental factors. Prior to the turn of the twentieth century and the rediscovery in 1990 of Gregor Mendel's work on heredity, a wide variety of hereditary causes were postulated (such as direct environmental effects acting on the mother's or father's germ cells or indirectly on the fetus via the mother during pregnancy). After the rediscovery of Mendel, theories of biological determinism came more and more to be formulated in terms of the new science of genetics, so that today biological and genetic determinism are virtually synonymous.

In the eighteenth and nineteenth centuries, theories of biological determinism were based on vague, often highly controversial ideas about of the nature of heredity. Since the concepts and tools were not available during that period to study heredity directly, biologists and anthropologists measured physical features of humans, trying to associate mental and personality traits with some anatomical (occasionally a physiological) feature, such as facial angle (angle of slope of the face from chin to forehead) or cranial index (ratio of lateral to vertical circumference of the head). Certain physical features, such as high cheekbones or a prominent eyebrow ridge, were often said to be indicative of criminal tendencies. With the growing acceptance of Mendelian genetics in the first half of the twentieth century, most theories of biological determinism came to locate the causal element in defective genes. With the revolution in molecular genetics during the second half of the century, defective genes became identified with altered sequences of the molecule of heredity, deoxyribonucleic acid (DNA).

Throughout its history, theories of biological determinism have been particularly applied to what were conceived of at the time as negative physical traits such as cleft palate, clubfoot, dwarfism, gigantism, foreshortened appendages, and social traits such as criminality, feeblemindedness, pauperism, shiftlessness, promiscuity, “feeble inhibition,” manic depression, and hyperkinesis (hyperactivity). Many of these later conditions or traits we would refer to as disabilities today, and the claim that most or all of them are inherited was, and is, highly controversial. This is partly a result of the difficulty in obtaining rigorous data about the genetics of such traits, especially when there is no established definition on which all investigators can agree. (What is criminality or alcoholism, or when does exuberance become hyperkinesis?) It is also a result of the fact that so many other factors [Page 173]interact with whatever genetic elements are present that it is difficult to tease them apart. Thus, throughout recent history, attempts to show that certain disabilities were genetic have had little success.

One of the most prominent movements to apply genetics to understanding social and personality traits emerged early in the twentieth century as the eugenics movement. Eugenics was a term coined by British geographer, statistician, and general polymath Francis Galton (1822–1911), first cousin of Charles Darwin. By “eugenics,” Galton meant “well” or “purely born,” and he argued for planned breeding among the “best stock” of the human population, along with various methods to discourage or prevent breeding among the “worst stock.” It was the belief of eugenicists such as Galton, his student Karl Pearson (1857–1936), and their American convert Charles B. Davenport (1866–1944) that most social problems were due to the accumulation of genetic defects, producing an increasingly disabled, or “degenerate,” population. Society was deteriorating through the increased reproduction of the disabled—particularly the mentally disabled. Various forms of inherited mental disability were said to be the root cause of social problems as varied as crime, alcoholism, and pauperism (in all cases, it was claimed that low mental ability led to inability to cope in a complex society, and hence the turn to antisocial behaviors).

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