Nature versus nurture is a long-standing debate in biology, psychology, and social sciences about whether the human individual receives more influence from their genetic inheritance and biology ("nature") or from their environment and upbringing ("nurture"). In other words, is a person's disposition, behavior, personality, sense of self, etc. more determined by their internal genetically and biologically inherited traits or by external factors after conception e.g. their exposure, life experience, and learning.
The phrase in its modern sense was popularized by the Victorian polymath Francis Galton, the modern founder of eugenics and behavioral genetics when he was discussing the influence of heredity and environment on social advancement. Galton was influenced by On the Origin of Species written by his half-cousin, the evolutionary biologist Charles Darwin. The complementary combination of the two concepts is an ancient concept ().In Plato's Protagoras 351b; an opposition is made by Protagoras' character between art on one hand and constitution and fit nurture (nature and nurture) of the soul on the other, art (as well as rage and madness; ) contributing to boldness (), but nature and nurture combine to contribute to courage ().
"Protagoras, in spite of the misgiving of Socrates, has no scruple in announcing himself a teacher of virtue, because virtue in the sense by him understood seems sufficiently secured by nature and nurture." Mackay, Robert W. 1869. "Introduction to the 'Meno' in comparison with the 'Protagoras'." Pp. 133–50 in Plato's Meno: A Dialogue on the Nature and Meaning of Education. London: Williams and Norgate. p. 138.
The view that humans acquire all or almost all their behavioral traits from "nurture" was termed tabula rasa ('blank tablet, slate') by John Locke in 1690. A blank slate view (sometimes termed blank-slatism) in human developmental psychology, which assumes that human behavioral traits develop almost exclusively from environmental influences, was widely held during much of the 20th century. The debate between "blank-slate" denial of the influence of heritability, and the view admitting both environmental and heritable traits, was at the core of an ideological dispute over research agendas throughout the second half of the 20th century.
Today, the idea of a strong dichotomy of nature versus nurture is generally considered to have limited relevance. Both "nature" and "nurture" factors have been found to contribute substantially, often in an inextricable manner, to many processes studied by biologists, psychologists and anthropologists.Moore, David S. 2003. The Dependent Gene: The Fallacy of 'Nature Vs. Nurture'. US: Henry Holt. . .Esposito, E. A., E. L. Grigorenko, and Robert J. Sternberg. 2011. "The Nature–Nurture Issue (an Illustration Using Behaviour-Genetic Research on Cognitive Development)." In An Introduction to Developmental Psychology (2nd ed.), edited by A. Slater and G. Bremner. British Psychological Society Blackwell. p. 85.Carlson, N. R. et al. 2005. Psychology: the science of behaviour (3rd Canadian ed.). Pearson. .Ridley, M. 2003. Nature via Nurture: Genes, Experience, & What Makes Us Human. HarperCollins. . Feedback loops have been found in which nature and nurture influence one another constantly, as seen in self-domestication. In ecology and behavioral genetics, researchers posit that nurture has an essential influence on the nature of an individual. Similarly in other fields, the dividing line between an inherited and an acquired trait has become unclear, as in epigenetics and fetal development.Hannay, Timo. 2014. "Nature Versus Nurture | What Scientific Idea is Ready for Retirement?" Edge. Edge Foundation, Inc. Retrieved 21 June 2020.
History of the debate
According to Records of the Grand Historian (94 BC) by Sima Qian, during Chen Sheng Wu Guang uprising in 209 B.C., Chen Sheng asked the rhetorical question as a call to war: "Are kings, generals, and ministers merely born into their kind?" (). Though Chen was obviously negative to the question, the phrase has often been cited as an early quest into the nature versus nurture problem.李盟编, DNA密码,中国言实出版社, 2012.04,第133页
John Locke's An Essay Concerning Human Understanding (1690) is often cited as the foundational document of the blank slate view. In the Essay, Locke specifically criticizes René Descartes's claim of an innate idea of God that is universal to humanity. Locke's view was harshly criticized in his own time. Anthony Ashley-Cooper, 3rd Earl of Shaftesbury, complained that by denying the possibility of any innate ideas, Locke "threw all order and virtue out of the world," leading to total moral relativism. By the 19th century, the predominant perspective was contrary to that of Locke's, tending to focus on "instinct." Leda Cosmides and John Tooby noted that William James (1842–1910) argued that humans have more instincts than animals, and that greater freedom of action is the result of having more psychological instincts, not fewer.
The question of "innate ideas" or "instincts" was of some importance in the discussion of free will in moral philosophy. In 18th-century philosophy, this was cast in terms of "innate ideas" establishing the presence of a universal virtue, a prerequisite for objective morals. In the 20th century, this argument was in a way inverted, since some philosophers (J. L. Mackie) now argued that the evolutionary origins of human behavioral traits forces us to concede that there is no foundation for ethics, while others (Thomas Nagel) treated ethics as a field of cognitively valid statements in complete isolation from evolutionary considerations.
Early to mid-20th century In the early 20th century, there was an increased interest in the role of one's environment, as a reaction to the strong focus on pure heredity in the wake of the triumphal success of Darwin's theory of evolution.Craven, Hamilton. 1978. The Triumph of Evolution: The Heredity-Environment Controversy, 1900–1941: "While it would be inaccurate to say that most American experimentalists concluded as the result of the general acceptance of Mendelism by 1910 or so that heredity was all powerful and environment of no consequence, it was nevertheless true that heredity occupied a much more prominent place than environment in their writings." During this time, the social sciences developed as the project of studying the influence of culture in clean isolation from questions related to biology. Franz Boas's The Mind of Primitive Man (1911) established a program that would dominate American anthropology for the next 15 years. In this study, he established that in any given population, biology, language, material, and symbolic culture, are autonomous; that each is an equally important dimension of human nature, but that none of these dimensions is reducible to another.
Purist behaviorism John B. Watson in the 1920s and 1930s established the school of purist behaviorism that would become dominant over the following decades. Watson is often said to have been convinced of the complete dominance of cultural influence over anything that heredity might contribute. This is based on the following quote which is frequently repeated without context, as the last sentence is frequently omitted, leading to confusion about Watson's position:Watson, John B. 1930. Behaviorism. p. 82.During the 1940s to 1960s, Ashley Montagu was a notable proponent of this purist form of behaviorism which allowed no contribution from heredity whatsoever:Montagu, Ashley. 1968. Man and Aggression, cited by In 1951, Calvin Hall suggested that the dichotomy opposing nature to nurture is ultimately fruitless.Hall, Calvin S. 1951. "The Genetics of Behavior." Pp. 304–29 in Handbook of Experimental Psychology, edited by S. S. Stevens. New York: John Wiley and Sons.
In African Genesis (1961) and The Territorial Imperative (1966), Robert Ardrey argues for innate attributes of human nature, especially concerning territoriality. Desmond Morris in The Naked Ape (1967) expresses similar views. Organised opposition to Montagu's kind of purist "blank-slatism" began to pick up in the 1970s, notably led by E. O. Wilson (On Human Nature, 1979).
The tool of twin studies was developed as a research design intended to exclude all confounders based on inherited behavioral traits. Such studies are designed to decompose the variability of a given trait in a given population into a genetic and an environmental component. Studies using twin neuroimaging methods show that genetic elements explain more of the variation in cognitive processing than in emotional regulation, which indicates that environmental factors play a greater role in shaping affective traits. Twin studies established that there was, in many cases, a significant heritable component. These results did not, in any way, point to overwhelming contribution of heritable factors, with heritability typically ranging around 40% to 50%, so that the controversy may not be cast in terms of purist behaviorism vs. purist nativism. Rather, it was purist behaviorism that was gradually replaced by the now-predominant view that both kinds of factors usually contribute to a given trait, anecdotally phrased by Donald Hebb as an answer to the question "which, nature or nurture, contributes more to personality?" by asking in response, "Which contributes more to the area of a rectangle, its length or its width?"Meaney M. 2004. "The nature of nurture: maternal effects and chromatin remodelling." In Essays in Social Neuroscience, edited by J. T. Cacioppo and G. G. Berntson. MIT Press. .
In a comparable avenue of research, anthropologist Donald Brown in the 1980s surveyed hundreds of anthropological studies from around the world and collected a set of cultural universals. He identified approximately 150 such features, coming to the conclusion there is indeed a "universal human nature", and that these features point to what that universal human nature is.
Determinism
At the height of the controversy, during the 1970s to 1980s, the debate was highly ideologised. In Not in Our Genes: Biology, Ideology and Human Nature (1984), Richard Lewontin, Steven Rose and Leon Kamin criticise "genetic determinism" from a Marxist framework, arguing that "Science is the ultimate legitimator of bourgeois ideology ... If biological determinism is a weapon in the struggle between classes, then the universities are weapons factories, and their teaching and research faculties are the engineers, designers, and production workers." The debate thus shifted away from whether heritable traits exist to whether it was politically or ethically permissible to admit their existence. The authors deny this, requesting that evolutionary inclinations be discarded in ethical and political discussions regardless of whether they exist or not.Kohn, A. (2008) The Brighter Side of Human Nature. Basic Books.
1990s Heritability studies became much easier to perform, and hence much more numerous, with the advances of genetic studies during the 1990s. By the late 1990s, an overwhelming amount of evidence had accumulated that amounts to a refutation of the extreme forms of "blank-slatism" advocated by Watson or Montagu.