There are a number of controversies surrounding the subject of human intelligence. It should be noted that there is no universally accepted definition of intelligence; one definition is the ability to reason, plan, solve problems, think abstractly, comprehend ideas and language, and learn. Foremost, it should be noted that although some of the controversies described here have attracted significant media coverage, they are considered to occur outside of the realm of mainstream science, and the theories sustaining them are widely considered fringe.
National income "IQ and the Wealth of Nations" is a controversial 2002 book by Dr. Richard Lynn, Professor Emeritus of Psychology at the University of Ulster, Northern Ireland, and Dr. Tatu Vanhanen, Professor Emeritus of Political Science at the University of Tampere, Tampere, Finland. The book argues that differences in national income (in the form of per capita gross domestic product) correlate with differences in the average national intelligence quotient (IQ). The authors interpret this correlation as showing that IQ is one important factor contributing to differences in national wealth and rates of economic growth, but that it is not the only determinant of these differences. The data, methodology, and conclusions have been criticized.
Lynn has been frequently criticized as a Pioneer fund grantee. The figures in the book were obtained by taking unweighted averages of different IQ tests. In 104 of the world's nations there were no IQ studies at all and IQ was estimated based on IQ in surrounding nations. The number of participants in each study was usually limited, often numbering under a few hundred. Studies that were averaged together often used different methods of IQ testing, different scales for IQ values and/or were done decades apart. The notion that there is such a thing as a culturally neutral intelligence test is disputed. It is generally agreed many factors, including environment, culture, demographics, wealth, pollution, and educational opportunities, affect measured IQ. See also Health and intelligence.
Gender related
Sex and intelligence research investigates differences in the distributions of cognitive skills between men and women. This research employs experimental tests of cognitive ability, which take a variety of forms, including written tests like the SAT. Research focuses on differences in individual skills as well as overall differences in general cognitive ability, which is often called g. IQ tests, specially designed to measure cognitive ability, usually test a variety of skills, and IQ scores are often used as a measure of g.
The population of men and women differ on average in how well they perform on some of these skill tests, but do equally well on other tests. For example, women tend to score higher on certain verbal and memory tests, whereas men tend to score higher on spatial tests, particularly mental spatial rotations.
While these results are relatively uncontroversial, the question of whether men and women differ on average in g is a matter of debate among experts. Most studies unambiguously find that men as a population are more varied than women in g (i.e. they have a higher variance and therefore there are more men than women at the extremes of ability).
However, determining whether men and women differ on average has been more difficult. It is easy to design an IQ test in which either males or females score higher on average, by selecting different tests or giving them different weights, so the question boils down to which weights the different tests should have for the g factor.
The primary reason for expecting that men will have higher average g than women is the male advantage in brain size. Resolving this question requires the use of sophisticated statistical techniques to extract g from the results of IQ tests. Some studies find an average male advantage in g, but most do not.
Race related Evolutionary :See also: Human evolution
Richard Lynn has proposed that the exposure to two recent ice ages, one 77,000-50,000 years ago, and another, more severe one 28,000-10,000 years ago, created evolutionary pressures which increased the intelligence of Europeans and East Asians significantly above other world populations. However, Lynn's views are controversial and the increased intelligence of Europeans and East Asians over other races is a matter of dispute.
J. Philippe Rushton, a professor of psychology at the University of Western Ontario and the current head of the Pioneer fund, has written a controversial book called Race, Evolution, and Behavior: A Life History Perspective. Rushton claims in the book that race is a valid biological concept and that racial differences frequently arrange in a continuum of Mongoloids (Orientals, East Asians) at one extreme, Negroids (blacks, Africans) at the opposite extreme, and Caucasoids (whites, Europeans) in the middle. Rushton also claims that the survival challenges of making warm clothes, building durable shelter, preserving food, and strategically hunting large animals, all selected genes for greater intelligence and social organization among the populations that migrated to cold climates.
According to the Out of Africa hypothesis, one or more subgroups of early modern humans left Africa between 55,000 and 60,000 years ago to become the ancestors of the non-African populations. Population-level differences in climate-selected traits such as skin color evolved in this time period. Gerhard Meisenberg suggested in the Mankind Quarterly that a similar time scale applies to the evolution of possible cognitive differences between human populations. Meisenberg argues that measurements of genetic diversity by the population geneticist Luigi Luca Cavalli-Sforza indicate that the difference in “genotypic” intelligence between the most divergent human populations caused by random genetic drift should be about 12 IQ points.
In his 2007 book, "Avoid Boring People: Lessons From a Life in Science", James D. Watson writes, "There is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically." "Our wanting to reserve equal powers of reason as some universal heritage of humanity will not be enough to make it so."
According to Linda S. Gottfredson technological innovation has been in a significant role in the evolution of human intelligence. Members of lower social classes are the largest risk. As new technologies have created new physical hazards this disparity has increased. Consequently, new technologies have gradually increased the IQ level of a population which has increased the capacity of the population to produce new innovations and led to further gains in intelligence.
Contemporary
The study of race and intelligence is the controversial study of how human intellectual capacities may vary among the different population groups commonly known as races. This study seeks to identify and explain the differences in manifestations of intelligence (e.g. IQ testing results), as well as the underlying causes of such variance.
Theories about the possibility of a relationship between race and intelligence have been the subject of speculation and debate since the 16th century. The contemporary debate focuses on the nature, causes, and importance, or lack of importance, of ethnic differences in intelligence test scores and other measures of cognitive ability, and whether "race" is a meaningful biological construct with significance other than its correlation to membership of particular ethnic groups. Thus, the question of the relative roles of nature and nurture in causing individual and group differences in cognitive ability is seen as fundamental to understanding the debate.
The modern controversy surrounding intelligence and race focuses on the results of IQ studies conducted during the second half of the 20th century in the United States, Western Europe, and other industrialized nations.
