gloria_b said:
Since when have we discovered a gene for intelligence?
Scientists have found that identical twins separated at birth and raised apart are very similar in IQ. Remarkably, twins reared apart are as similar as identical twins reared together by the time they're adults. They also resemble one another strikingly in their mannerisms, the way they laugh, their likes and dislikes, phobias, temperament, sexual preference, educational achievement, income, conscientiousness, musical ability, sense of humor, whether they're criminals or law-abiding, and pretty much everything else that's ever been tested, even traits as peculiar as which vegetables they refuse to eat (Bouchard, 1993). The extent of their similarity amazes even the researchers and the twins themselves.
The primacy of genes is likewise demonstrated by adoption studies. Adopted children's IQs resemble those of their biological parents far more closely than they resemble those of their adoptive parents, who essentially provided them with their environments from the time of birth onwards. When adopted children are grown, there's virtually no resemblance between their IQs and those of their adoptive parents (Loehlin, Willerman, and Horn, 1987).
The dominant role of heredity in determining IQ is not a theory, it's an established fact, the consensus of hundreds of studies conducted in different times and places by many different researchers. But the public is largely unaware of this fact because the liberal media have told them repeatedly that most experts in IQ testing believe IQ is largely environmental. In reality, the majority of researchers in the field of intelligence testing believes heredity is the more important factor (Snyderman and Rothman, 1988).
Why is it now that the unitelligent are repoducing more? Why were the unintelligent reproducing a lot before now?
For hundreds of years, until the early 1800s in England and America, there was natural fertility, i.e., no efforts to limit the number of births. Married couples tended to have many children, but not everyone could marry. Men who didn't earn enough to support a family remained single and childless, and the net result was a small positive relationship between fertility and intelligence. Then several books on contraception were published which naturally affected those who could read disproportionately. Condoms and diaphragms became available, and the birth rate of the middle and upper classes declined. By the middle of the century it had become apparent that educated people were having fewer children than the uneducated.
This caused considerable alarm, and a number of studies were undertaken both in England and America in the early decades of the 20th century. Schoolchildren's IQs were found to correlate negatively with their number of siblings, which seemed to confirm fears of dysgenic fertility, but this conclusion was questioned because there was no way to know the IQs of the childless. Later, some U.S. studies of adult IQ and number of offspring reported negative correlations, but other similar studies found no correlation. However, the samples used in all these studies were not representative of the U.S. population as a whole — they were restricted either in terms of race, birth cohort, or geographical area. So by mid-to-late 20th century, there was still no definitive answer to the question of dysgenic fertility. Then in 1984, Frank Bean and Marian van Court had the good fortune to discover an excellent data set, the General Social Survey (GSS), to test the hypothesis. It included a short vocabulary test devised by Thorndike to provide a rough grading of mental ability which was ideal for our study. The GSS had interviewed a large, representative sample of the U.S. population whose reproductive years fell between 1912 and 1982, yielding data which provided the unique opportunity of an overview of the relationship between fertility and IQ for most of the 20th century. In all 15 of the 5-year cohorts, correlations between test scores and number of offspring were negative, and 12 of 15 were statistically significant (Van Court and Bean, 1985).
Recently, Richard Lynn and Marian van Court did a follow-up study which included new data collected in the 1990s by the GSS, and they got very similar results. They calculated that .9 IQ points were being lost per generation (Lynn and Van Court, 2003). To find out how much has been lost during the 20th century, we can simply multiply .9 x 4 generations = 3.6 IQ points. There are no precise data for the latter part of the 19th century, but there's every indication that the period of 1875-1900 was seriously dysgenic. So as a rough (but conservative) estimate of the total 125-year loss, we can multiply .9 x 5 generations = 4.4 IQ points lost from 1875 to the present. A loss of this magnitude would approximately halve those with IQs over 130, and double those with IQs below 70.
In Dysgenics: Genetic Deterioration in Modern Populations, Richard Lynn (1996) found that dysgenic fertility is the rule rather than the exception around the world. There haven't been as many studies done in Europe, but it appears to be about on a par with the U.S. in terms of the severity of the dysgenic trend. The only place dysgenic fertility is not found is sub-Saharan Africa where birth control is not used.
As the reader may have begun to suspect, the main reason for dysgenic fertility is that intelligent women use birth control more successfully than unintelligent women do. This seems to be the case regardless of which method is used. Women of high, average, and low-IQ all want, on average, the same number of children, but low-IQ women have far more accidental pregnancies, and thus more children. If all women had the exact number of children they desired, there would be virtually no dysgenic fertility (Van Court, 1984). A second factor is that very intelligent and successful women (doctors, lawyers, professors, and women working at high levels in business) often end up having far fewer children than they would like to have. A recent study found that 33-43% of professional women are childless by age 41-55, and only 14% of them are childless by choice (Hewlett, 2002).
My sources:
Bouchard, Thomas, (1993), Twins as a Tool of Behavioral Genetics. New York: J. Wiley
Brand, Christopher (1996) The 'g' Factor, New York: Wiley & Sons
Flynn, J.R., (1984) The mean IQ of Americans: Massive gains 1932 to 1978, Psychological Bulletin, 95, 29-51
Hewlett, Sylvia Ann, Creating a Life: Professional Women and the Quest for Children, New York: Talk Miramax Books, 2002, p. 86-87
Jencks, Christopher (1972), Inequality, New York: Basic Books Inc.
Herrnstein, Richard, and Murray, Charles, (1994) The Bell Curve, p. 368, New York: New York Free Press
Loehlin, J., Willerman, L., Horn, J. (1990) Heredity, environment, and personality change: evidence from the Texas Adoption Project, Journal of Personality 58:1, p.221-246
Lynn, Richard (1996), Dysgenics: Genetic Deterioration in Modern Populations, Westport, Conn.: Praeger
Lynn, Richard (2001), Eugenics: A Reassessment, Westport, CT: Praeger
Lynn, Richard, and Van Court, Marian (2003) New evidence of dysgenic fertility for intelligence in the United States, Intelligence 32:2, March, p.193-201,
www.eugenics.net
Lynn, Richard and Vanhanen, Tatu (2002), IQ and the Wealth of Nations, Westport, Conn: Praeger
MacDonald, Kevin (1998), The Culture of Critique: An Evolutionary Analysis of Jewish Involvement in Twentieth-Century Intellectual and Political Movements, Westport CT: Praeger
Murray, Charles (1984), Losing Ground: American Social Policy, 1950-1980, New York: Basic Books
Reed, E.W., and Reed, S.C., (1965) Mental Retardation: A Family Study, Philadelphia: W. B. Saunders, p. 78
Rushton, J.P., (1999), "Secular gains in IQ not related to the g factor and inbreeding depression unlike Black-White differences: A reply to Flynn," Personality and Individual Differences, 26, p.381-389
Snyderman, Mark, and Rothman, Stanley (1988), The IQ Controversy, the Media, and Public Policy, New Brunswick: Transaction Books
Van Court, Marian (1983 ) Unwanted births and dysgenic reproduction in the United States, The Eugenics Bulletin, Spring, 1983,
www.eugenics.net
Van Court, Marian and Bean, Frank (1985), Intelligence and Fertility in the United States: 1912 to 1982, Intelligence 9, p.23-32,
www.eugenics.net
And what ever happened to ignorance is bliss?
Eugenics is for those who favor truth above all else.
Regards.
