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Eugenics is a set of beliefs and practices that aim to improve the genetic quality of a human population. Historically, eugenicists have altered various human gene frequencies by inhibiting the fertility of people and groups purported to be inferior or promoting that of those purported to be superior.
An intelligence quotient (IQ) is a total score derived from a set of standardised tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern for the German term Intelligenzquotient, his term for a scoring method for intelligence tests at University of Breslau he advocated in a 1912 book.
Discussions of race and intelligence – specifically regarding claims of differences in intelligence along racial lines – have appeared in both popular science and academic research since the modern concept of race was first introduced. With the inception of IQ testing in the early 20th century, differences in average test performance between racial groups were observed, though these differences have fluctuated and in many cases steadily decreased over time. Complicating the issue, modern science has concluded that race is a socially constructed phenomenon rather than a biological reality, and there exist various conflicting definitions of intelligence. In particular, the validity of IQ testing as a metric for human intelligence is disputed. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between groups, and that observed differences are environmental in origin.
The Bell Curve: Intelligence and Class Structure in American Life is a 1994 book by psychologist Richard J. Herrnstein and political scientist Charles Murray, in which the authors argue that human intelligence is substantially influenced by both inherited and environmental factors and that it is a better predictor of many personal outcomes, including financial income, job performance, birth out of wedlock, and involvement in crime than are an individual's parental socioeconomic status. They also argue that those with high intelligence, the "cognitive elite", are becoming separated from those of average and below-average intelligence, and that this separation is a source of social division within the United States.
Nature versus nurture is a long-standing debate in biology and society about the relative influence on human beings of their genetic inheritance (nature) and the environmental conditions of their development (nurture). The alliterative expression "nature and nurture" in English has been in use since at least the Elizabethan period and goes back to medieval French. The complementary combination of the two concepts is an ancient concept. Nature is what people think of as pre-wiring and is influenced by genetic inheritance and other biological factors. Nurture is generally taken as the influence of external factors after conception e.g. the product of exposure, experience and learning on an individual.
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid inbreeding only rarely.
Twin studies are studies conducted on identical or fraternal twins. They aim to reveal the importance of environmental and genetic influences for traits, phenotypes, and disorders. Twin research is considered a key tool in behavioral genetics and in related fields, from biology to psychology. Twin studies are part of the broader methodology used in behavior genetics, which uses all data that are genetically informative – siblings studies, adoption studies, pedigree, etc. These studies have been used to track traits ranging from personal behavior to the presentation of severe mental illnesses such as schizophrenia.
Richard Lynn was a controversial English psychologist and self-described "scientific racist" who advocated for a genetic relationship between race and intelligence. He was the editor-in-chief of Mankind Quarterly, a white supremacist journal. He was a professor emeritus of psychology at Ulster University, but had the title withdrawn by the university in 2018. Lynn was lecturer in psychology at the University of Exeter and professor of psychology at the Economic and Social Research Institute, Dublin, and at the University of Ulster at Coleraine.
Hereditarianism is the research program according to which heredity plays a central role in determining human nature and character traits, such as intelligence and personality. Hereditarians believe in the power of genetic influences to explain human behavior and [[eugenics|solve human social-political problems.]] They stress the value of evolutionary explanations in all areas of the human sciences.
Devolution, de-evolution, or backward evolution is the notion that species can revert to supposedly more primitive forms over time. The concept relates to the idea that evolution has a divine purpose (teleology) and is thus progressive (orthogenesis), for example that feet might be better than hooves, or lungs than gills. However, evolutionary biology makes no such assumptions, and natural selection shapes adaptations with no foreknowledge or foresights of any kind regarding the outcome. It is possible for small changes to be reversed by chance or selection, but this is no different from the normal course of evolution and as such de-evolution is not compatible with a proper understanding of evolution due to natural selection.
Geoffrey Franklin Miller is an American evolutionary psychologist, author, and associate professor of psychology at the University of New Mexico. He is known for his research on sexual selection in human evolution.
Research on the heritability of IQ inquires into the degree of variation in IQ within a population that is due to genetic variation between individuals in that population. There has been significant controversy in the academic community about the heritability of IQ since research on the issue began in the late nineteenth century. Intelligence in the normal range is a polygenic trait, meaning that it is influenced by more than one gene, and in the case of intelligence at least 500 genes. Further, explaining the similarity in IQ of closely related persons requires careful study because environmental factors may be correlated with genetic factors.
The relationship between fertility and intelligence has been investigated in many demographic studies. There is evidence that, on a population level, measures of intelligence such as educational attainment and literacy are negatively correlated with fertility rate in some contexts.
Behavioural genetics, also referred to as behaviour genetics, is a field of scientific research that uses genetic methods to investigate the nature and origins of individual differences in behaviour. While the name "behavioural genetics" connotes a focus on genetic influences, the field broadly investigates the extent to which genetic and environmental factors influence individual differences, and the development of research designs that can remove the confounding of genes and environment. Behavioural genetics was founded as a scientific discipline by Francis Galton in the late 19th century, only to be discredited through association with eugenics movements before and during World War II. In the latter half of the 20th century, the field saw renewed prominence with research on inheritance of behaviour and mental illness in humans, as well as research on genetically informative model organisms through selective breeding and crosses. In the late 20th and early 21st centuries, technological advances in molecular genetics made it possible to measure and modify the genome directly. This led to major advances in model organism research and in human studies, leading to new scientific discoveries.
The history of the race and intelligence controversy concerns the historical development of a debate about possible explanations of group differences encountered in the study of race and intelligence. Since the beginning of IQ testing around the time of World War I, there have been observed differences between the average scores of different population groups, and there have been debates over whether this is mainly due to environmental and cultural factors, or mainly due to some as yet undiscovered genetic factor, or whether such a dichotomy between environmental and genetic factors is the appropriate framing of the debate. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between racial groups.
The evolution of schizophrenia refers to the theory of natural selection working in favor of selecting traits that are characteristic of the disorder. Positive symptoms are features that are not present in healthy individuals but appear as a result of the disease process. These include visual and/or auditory hallucinations, delusions, paranoia, and major thought disorders. Negative symptoms refer to features that are normally present but are reduced or absent as a result of the disease process, including social withdrawal, apathy, anhedonia, alogia, and behavioral perseveration. Cognitive symptoms of schizophrenia involve disturbances in executive functions, working memory impairment, and inability to sustain attention.
The history of eugenics is the study of development and advocacy of ideas related to eugenics around the world. Early eugenic ideas were discussed in Ancient Greece and Rome. The height of the modern eugenics movement came in the late 19th and early 20th centuries.
Evolutionary psychiatry, also known as Darwinian psychiatry, is a theoretical approach to psychiatry that aims to explain psychiatric disorders in evolutionary terms. As a branch of the field of evolutionary medicine, it is distinct from the medical practice of psychiatry in its emphasis on providing scientific explanations rather than treatments for mental disorder. This often concerns questions of ultimate causation. For example, psychiatric genetics may discover genes associated with mental disorders, but evolutionary psychiatry asks why those genes persist in the population. Other core questions in evolutionary psychiatry are why heritable mental disorders are so common how to distinguish mental function and dysfunction, and whether certain forms of suffering conveyed an adaptive advantage. Disorders commonly considered are depression, anxiety, schizophrenia, autism, eating disorders, and others. Key explanatory concepts are of evolutionary mismatch and the fact that evolution is guided by reproductive success rather than health or wellbeing. Rather than providing an alternative account of the cause of mental disorder, evolutionary psychiatry seeks to integrate findings from traditional schools of psychology and psychiatry such as social psychology, behaviourism, biological psychiatry and psychoanalysis into a holistic account related to evolutionary biology. In this sense, it aims to meet the criteria of a Kuhnian paradigm shift.
Schizophrenia is a mental disorder characterized by persistent hallucinations, delusions, paranoia, and thought disorder. These experiences are evident in multiple sensory modalities and include deviation in all facets of thought, cognition, and emotion. Compared to other psychological disorders like major depressive disorder (MDD) and generalized anxiety disorder (GAD), schizophrenia has significantly higher heritability. Schizophrenia has been found to present cross-culturally, and it almost always has 0.1% prevalence in a given population, although some studies have cast doubts on this. It has been hypothesized that schizophrenia is unique to human beings and has existed for a long time.
In behavioral genetics, the Scarr–Rowe effect, also known as the Scarr–Rowe hypothesis, refers to the proposed moderating effect of low socioeconomic status on the heritability of children's IQ. According to this hypothesis, lower socioeconomic status and greater exposure to social disadvantage during childhood leads to a decrease in the heritability of IQ, as compared to children raised in more advantaged environments. It is considered an example of gene–environment interaction. This hypothesized effect was first proposed by Sandra Scarr, who found support for it in a 1971 study of twins in Philadelphia, and these results were replicated by David C. Rowe in 1999. Since then, similar results have been replicated numerous times, though not all replication studies have yielded positive results. A 2015 meta-analysis found that the effect was predominant in the United States while less evident in societies with robust child welfare systems.
References
- ↑ Rédei, George P. (2008). Encyclopedia of Genetics, Genomics, Proteomics, and Informatics, Volume 1. Springer. p. 572. ISBN 978-1-4020-6755-6.
- ↑ Jordan, David Starr (2003). War and the Breed: The Relation of War to the Downfall of Nations (Reprint ed.). Honolulu: University Press of the Pacific. ISBN 978-1-4102-0900-9.
- ↑ Carlson, Elof Axel (2001). The Unfit: A History of a Bad Idea. Cold Spring Harbor Laboratory Press. pp. 189–193. ISBN 9780879695873.
- ↑ Carlson, Elof Axel (2001). The Unfit: A History of a Bad Idea. Cold Spring Harbor Laboratory Press. ISBN 9780879695873.
- 1 2 Fischbach, Karl-Friedrich; Niggeschmidt, Martin (2022). "Do the Dumb Get Dumber and the Smart Get Smarter?". Heritability of Intelligence. Springer. pp. 37–39. doi:10.1007/978-3-658-35321-6_9. ISBN 978-3-658-35321-6. S2CID 244640696.
Since the nineteenth century, a 'race deterioration' has been repeatedly predicted as a result of the excessive multiplication of less gifted people. Nevertheless, the educational and qualification level of people in the industrialized countries has risen strongly. The fact that the 'test intelligence' has also significantly increased, is difficult to explain for supporters of the dysgenic thesis: they suspect that the 'phenotypic intelligence' has increased for environmental reasons, while the 'genotypic quality' secretly decreases. There is neither evidence nor proof for this theory.
Citations in original omitted. - ↑ Lynn, Richard (1997). Dysgenics: Genetic Deterioration in Modern Populations (PDF). Praeger Publishers. ISBN 9780275949174.
- ↑ Conley, Dalton; Laidley, Thomas; Belsky, Daniel W.; Fletcher, Jason M.; Boardman, Jason D.; Domingue, Benjamin W. (14 June 2016). "Assortative mating and differential fertility by phenotype and genotype across the 20th century". Proceedings of the National Academy of Sciences. 113 (24): 6647–6652. Bibcode:2016PNAS..113.6647C. doi: 10.1073/pnas.1523592113 . PMC 4914190 . PMID 27247411.
- ↑ Bratsberg, Bernt; Rogeberg, Ole (26 June 2018). "Flynn effect and its reversal are both environmentally caused". Proceedings of the National Academy of Sciences. 115 (26): 6674–6678. Bibcode:2018PNAS..115.6674B. doi: 10.1073/pnas.1718793115 . PMC 6042097 . PMID 29891660.
- ↑ Neisser, Ulric (1998). The Rising Curve: Long-Term Gains in IQ and Related Measures. American Psychological Association. pp. xiii–xiv. ISBN 978-1557985033.
There is no convincing evidence that any dysgenic trend exists. . . . It turns out, counterintuitively, that differential birth rates (for groups scoring high and low on a trait) do not necessarily produce changes in the population mean.
- ↑ Wilmoth, John R. "Dysgenics: Genetic Deterioration in Modern Populations", Population and Development Review 23, no. 3 (Sep., 1997): 664-666.
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