The Mismeasure of Man is a 1981 book written by the Harvard paleontologist Stephen Jay Gould. The

book is a history and critique of the methods and motivations underlying biological determinism, the belief

that "the social and economic differences between human groups — primarily races, classes,

and sexes — arise from inherited, inborn distinctions and that society, in this sense, is an accurate

reflection of biology."[1]

The book also critiques the principal theme of biological determinism, that "worth can be assigned to

individuals and groups by measuring intelligence as a single quantity." Gould discusses two prominent

techniques used to measure such a quantity, craniometry and psychological testing. Gould describes

these methods as suffering from "two deep fallacies". The first fallacy is of reification, that is, "our

tendency to convert abstract concepts into entities." These entities include IQ (the intelligence quotient)

and g (the general intelligence factor), which have been the cornerstone of much intelligence research.

The second fallacy is one of ranking, or our "propensity for ordering complex variation as a gradual

ascending scale."

The Mismeasure of Man investigates "the abstraction of intelligence as a single entity, its location within

the brain, its quantification as one number for each individual, and the use of these numbers to rank

people in a single series of worthiness, invariably to find that oppressed and disadvantaged groups—

races, classes, or sexes—are innately inferior and deserve their status."[2]

The book's second edition (1996) was revised to challenge the controversial arguments of Richard

Herrnstein and Charles Murray's The Bell Curve.

Contents

 [hide]

1 Summary of contents

o 1.1 Historical bias in biological sociology

o 1.2 Bias and falsification

o 1.3 Statistical correlation and heritability

2 Reception

o 2.1 Awards and Accolades

o 2.2 Praise

o 2.3 Criticisms

2.3.1 Response by persons mentioned in book

2.3.2 Response to the revised edition

3 See also

4 External links

o 4.1 Praise

o 4.2 Criticism

5 Further reading

6 References

[edit]Summary of contents

Cover of the 1996 printing of The Mismeasure of Man.

[edit]Historical bias in biological sociology

The first parts of the book are devoted to a critical analysis of early works on the supposed biologically

inherited basis for intelligence, such ascraniometry, the measurement of skull volume and its relation to

intellectual faculties. Gould argues that much of this research was based more on prejudice than scientific

rigor, demonstrating how in several occasions researchers such as Samuel George Morton, Louis

Agassiz, and Paul Broca committed the fallacy of using their expected conclusions as part of their

reasoning. The book contains a complete re-working of Morton's original data of endocranial volume, and

asserts that the original results were based on biases and manipulations, both by the selection of data

and by Morton physically manipulating his results. Gould claims that when these purported biases are

accounted for, the original hypothesis—an ordering in skull size ranging from Blacks through Mongols to

Whites—is not supported in any way by the data. A subsequent study by John Michael found Morton's

original data to be more accurate than Gould describes, concluding that "contrary to Gould's

interpretation... Morton's research was conducted with integrity." However, there were some

discrepancies in Morton's calculations as well.[3] As of now, there are no definitive answers. This issue

remains to be resolved and is one of the most contested portions of the book.

[edit]Bias and falsification

The following chapters presented a historical evaluation of the concept of IQ and of the g factor, which

were and are measures of intelligence used by psychologists. Gould argued that most race-related

psychological studies have been heavily biased by the belief that human behavior was best explained

by heredity. Gould noted that the often-cited twin studies by Cyril Burt on the genetic heritability of

intelligence is often criticized for having used falsified data. According to L. S. Hearnshaw (1979), fraud

had also been found in Burt's studies in kinship correlations in IQ, and declining levels of intelligence in

Britain.

[edit]Statistical correlation and heritability

Gould devoted a large part of the book to an analysis of statistical correlation, which is used by

psychologists to assert the validity of IQ tests and the heritability of intelligence. For example, to claim that

an IQ test measures general intelligence factor, answers to various questions must correlate highly. The

heritability of g requires that the scores of respondents who are closely related exhibit higher correlation

than those of distant relations.

Gould pointed out that correlation was not the same as cause. As he put it, measures of the changes,

over time, in "my age, the population of Mexico, the price of Swiss cheese, my pet turtle's weight, and the

average distance between galaxies" have a high positive correlation, but that did not mean that Gould's

age goes up because the population of Mexico goes up. Second, and more specifically, a high positive

correlation between parent and child IQ can be taken as either evidence that IQ is genetically inherited or

that IQ is inherited through social and environmental factors. Since the same data can be used to argue

either side of the case, the data in and of itself are not useful.

Furthermore, Gould argued that even if it were demonstrated that IQ were highly genetically heritable

within a group, this does not explain the causes of IQ differences between groups or whether those

differences can be changed by environment. Gould gave the example of height, which was known to be

determined mostly through genes within socioeconomic groups, but group differences in height may be

due to nutrition as well as genes. Richard Lewontin, a colleague of Gould's, is well-known for

emphasizing this argument as it pertains to IQ testing.

According to Gould, a good example of the confusion of heritability is found in the statement "If all

environments were to become equal for everyone, heritability would rise to 100% because all remaining

differences in IQ would necessarily be genetic in origin."[4] He says that this claim is at best misleading

and at worst, false. First, it is very hard to conceive of a world in which everyone grows up in exactly the

same environment; the very fact that people are spatially and temporally dispersed means that no one

can be in exactly the same environment, for example, a husband and wife may share a house, but they

do not live in identical environments because each is married to a different person. Second, even if

people grew up in exactly the same environment, not all differences would be genetic in origin. This is

because embryonic development involves chance molecular events and random cellular movements that

alter the effects of genes.

Gould argues that heritability is not a measure of phenotypic differences between groups, but rather

differences between genotype and phenotype within a population. Even within a group, if all members of

the group grow up in exactly the same environment, it does not mean that heritability is 100%. All

Americans (or New Yorkers, or upper-class New Yorkers — one may define the population in question as

narrowly as one likes) may eat exactly the same food, but their adult height will still be a result of both

genetics and nutrition. In short, heritability is almost never 100%, and heritability tells us nothing about

genetic differences between groups. This is true for height, which has a high degree of heritability; it is all

the more true for intelligence. This is true for reasons other than those involving heritability, as Gould

discusses.

Gould also rejects the concept which IQ is meant to measure, "general intelligence" (or g). IQ tests, he

points out, ask many different kinds of questions. Responses to different kinds of questions tend to form

clusters. In other words, different kinds of questions can be given different scores — which suggests that

an IQ test is really a combination of a number of different tests that test a number of different things.

Gould claims that proponents of IQ tests assume that there is such a thing as general intelligence, and

analyze the data so as to produce one number, which they then claim is a measure of general

intelligence.

Gould argues that this one number (and therefore, the implication that there is a real thing called "general

intelligence" that this number measures) is in fact an artifact of the statistical operations psychologists

apply to the raw data. He argues that one can analyze the same data more effectively and end up with a

number of different scores (that are as or more valid, meaning they measure something) rather than one

score.

Finally, Gould points out that he is not opposed to the notion of "biological variability", which is the

premise that heredity influences intelligence. Instead, he does criticize the notion of "biological

determinism", which is the idea that genes determine destiny and there is nothing we can or should do

about this.

[edit]Reception

[edit]Awards and Accolades

The Mismeasure of Man won the National Book Critics Circle Award for non-fiction in 1981 and the

Outstanding Book Award from the American Educational Research Association in 1983. An Italian

translation won the Iglesias Prize in 1991. In December 2006 Discover magazine ranked The

Mismeasure of Man as the 17th greatest science book of all time.[5] In 1998, the Modern Library ranked it

as the 24th best non-fiction book of all time.[6]

[edit]Praise

Gould stated that one of the most positive reviews of the original edition had come from the British

Journal of Mathematical & Statistical Psychology, which Cyril Burt had once been an editor of. It stated

that, "Gould has performed a valuable service in exposing the logical basis of one of the most important

debates in the social sciences, and this book should be required reading for students and practitioners

alike."[7]

Leon J. Kamin, an American psychologist, writes that Gould's work "effectively anticipated and thoroughly

undermined" the arguments later presented in The Bell Curve. He praises the additions to the book's

1996 edition, writing that they "strengthen the claim of this book to be 'a major contribution toward

deflating pseudobiological "explanations" of our present social woes.'"[citation needed]

Journalist Christopher Lehmann-Haupt stresses Gould's critique of factor analysis, saying the book

"demonstrates persuasively how factor analysis led to the cardinal error in reasoning of confusing

correlation with cause, or, to put it another way, of attributing false concreteness to the abstract."[8]

The Saturday Review, a British journal, praises the book as a "fascinating historical study of scientific

racism" that "illustrate[s] both the logical inconsistencies of the theories and the prejudicially motivated,

albeit unintentional, misuse of data in each case."[9]

A review in the Sunday Times, another British publication, speaks favorably of the book, suggesting

Gould "shifts the argument from a sterile contest between environmentalists and hereditarians and turns it

into an argument between those who are impressed with what our biology stops us doing and those who

are impressed with what it allows us to do."[citation needed]

Richard York and Brett Clark of the US Monthly Review praise Gould's narrow focus: "Rather than

attempt a grand critique of all 'scientific' efforts aimed at justifying social inequalities, Gould performs a

well-reasoned assessment of the errors underlying a specific set of theories and empirical claims."[10]

[edit]Criticisms

Bernard Davis, professor of microbiology at the Harvard Medical School, accused Gould of setting

up straw man arguments, as well as incorrectly defining key terms (notably "reification"), choosing data in

a "highly selective" manner, and in general being motivated more by political concerns than scientific

ones.[11] Davis claimed that a laudatory review byPhilip Morrison, which appeared in Scientific American,

was written because the journal's editorial staff had "long seen the study of the genetics of intelligence as

a threat to social justice." According to Davis, the reviews of Gould's book in the popular and literary press

were generally very approbatory, whereas, in contrast, most reviews in scientific journals tended to be

critical of many aspects of the book. This claim was, however, countered by Gould, who argued that of a

total of 24 reviews written by academic experts in psychology, 14 were approbatory, three were mixed,

and only seven were critical.[12] Davis also pointed out that Gould mispresented a study by Henry H.

Goddard on the intelligence of Jewish, Hungarian, Italian, and Russian immigrants to America. According

to Gould, Goddard found that most members of these groups were "feeble-minded", whereas in reality

Goddard explicitly described in the first sentence of his paper that the subjects of the study were not

typical members of their groups but rather were selected because of their suspected sub-normal

intelligence.[13]

Statistician David J. Bartholomew, of the London School of Economics, wrote that Gould erred in his use

of factor analysis [14]  and irrelevantly focused on issue of reification and ignored scientific consensus on the

existence of the g factor of intelligence.[15] Psychologist John B. Carroll made similar criticisms, arguing

that Gould did not understand "the nature and purpose" of factor analysis.[16]

In an article written for the April 1982 edition of Nature, Steve Blinkhorn, a senior lecturer in psychology

at Hatfield Polytechnic, claimed The Mismeasure of Man was "a masterpiece of propaganda," which

selectively juxtaposed data in order to further a political agenda.[17]

Psychologist Franz Samelson wrote a review in Science, which tended to be critical on a number of

counts.[18] Samelson, for example, was critical of Gould's argument that U.S. Armyintelligence tests

contributed to the Immigration Restriction Act of 1924. According Mark Snyderman and Richard J.

Herrnstein, who studied the Congressional Record and committee hearings related to the Immigration

Act, "the [intelligence] testing community did not generally view its findings as favoring restrictive

immigration policies like those in the 1924 Act, and Congress took virtually no notice of intelligence

testing."[19]

In a 1983 review, psychologist Lloyd Humphreys, the then editor-in-chief of American Journal of

Psychology and Psychological Bulletin, described The Mismeasure of Man as "science fiction" and

"political propaganda". Among other things, he argued that Gould had mispresented the views of Alfred

Binet, Godfrey Thomson, and Lewis Terman.[20]

James R. Flynn, an intelligence researcher known for his criticisms of racial theories of intelligence,

argued that "Gould's book evades all of [Arthur] Jensen's best arguments for a genetic component in the

black-white IQ gap by positing that they are dependent on the concept of g as a general intelligence

factor. Therefore, Gould believes that if he can discredit g no more need be said. This is manifestly false.

Jensen's arguments would bite no matter whether blacks suffered from a score deficit on one or 10 or 100

factors."[21] Bernard Davis and Jensen himself have made this same criticism.[13][22]

According to psychologist Ian Deary, Gould's claim that there is no relation between brain size and IQ is

outdated. Furthermore, he reports that Gould refused to correct this in new editions of the book, even

though newly available data were brought to his attention by several researchers.[23]

[edit]Response by persons mentioned in book

Arthur Jensen, an educational psychologist at UC Berkeley, was heavily criticized in The Mismeasure of

Man. In his review of the book, Jensen accused Gould of using straw man arguments, misrepresenting

other scientists, and operating from a political agenda, arguing that the book itself is "a patent example" of

the biasing influence of ideology on science that it purports to portray. He also faulted Gould for

concentrating on long-ago disproven arguments instead of addressing "anything currently regarded as

important by scientists in the relevant fields".[22]

Psychologist Hans Eysenck was critiqued in The Mismeasure of Man for using a "non-causal" relationship

to defend a conclusion that black children have lower innate IQ.[24] Eysenck and Gould debated the book

in an exchange of letters to The New York Review of Books.[25][26] Eysenck's review called the book "a

paleontologist's distorted view of what psychologists think, untutored in even the most elementary facts of

the science." Gould criticized Eysenck's correlation of IQ with EEG evoked potentials by citing Arthur

Jensen's own work in Bias in Mental Testing (1980). Jensen could only find "correlations larger than

about -0.4 to -0.5" between reaction time and IQ, with typical correlations ranging between -0.3 and -0.4.

Jensen wrote: "The AEP average evoked potential and IQ research picture soon becomes a thicket of

seemingly inconsistent and confusing findings, confounded variables, methodological differences,

statistically questionable conclusions, unbridled theoretical speculation, and, not surprisingly,

considerable controversy."[27]

[edit]Response to the revised edition

Charles Murray, co-author of The Bell Curve, claimed that Gould misrepresented his views.[28]

Psychologist J. Philippe Rushton accused Gould of "scholarly malfeasance" for misrepresenting or

ignoring relevant scientific research, and attacking dead arguments and methods.[29]

[edit]See also

Race Differences in Intelligence: An Evolutionary Analysis is a 2006 book by Richard Lynn claiming

to represent the largest collection and review of the global cognitive ability data, by nine global regions,

surveying 620 published studies from around the world, with a total of 813,778 tested individuals.

Lynn's meta-analysis lists East Asians (105), Europeans (99), Inuit (91), Arabs [both Middle Easterners

and North Africans] (89 each), Pacific Islanders (85), Hispanics (84), Non-Bushmen Sub-Saharan

Africans (67), Australian Aborigines (62), Bushmen and Pygmies (54), Homo Erectus(50), Apes (22),

and Monkeys (12).[1][2][3]

Broadly speaking, Lynn estimates that about half of the IQ deficit of third world races can be explained by

inadequate nutrition, while the other half is racially genetic. For example Lynn argues that while Africans

living in Africa average IQ 67, African Americans living in the Southern United States (where European

admixture is very low) average IQ 80. Lynn believes the latter figure represents their genotypic

intelligence, while the IQs in Africa are stunted by malnutrition.

Ashkenazi Jews who Lynn classifies as South Asian/European hybrids, average 107-115 in

the U.S. and Britain, and Ashkenazi Jews in Israelaverage 103[4]. Lynn argues that the U.S.

Ashkenazis represent the elite who were intelligent enough to escape persecution in World War II.

However not all American Ashkenazi Jews were from the elite: two million Ashkenazi Jews arrived in the

U.S. between 1880 and 1920, the vast majority of whom were relatively poor when they arrived in the

U.S.[5]

Like much research regarding race and intelligence, Lynn's work has been controversial [6]. When taken

as national averages, the data available, particularly regarding the developing world, is speculative due to

limited sampling, year of testing, and varying type of cognitive ability test used. Lynn's survey is an

expansion by nearly four times of the data collected in his 2002 IQ and the Wealth of Nations with Tatu

Vanhanen, which dealt with the relationship between IQ and economic development. IQ and the Wealth

of Nations was criticized for error, alleged bias, andracism, but the book has also been used as a source

of IQ data and hypotheses in several peer-reviewed studies.[7] Lynn argues the surveyed studies have

high reliability in the sense that different studies give similar results, and high validity in the sense that

they correlate highly with performance in international studies of achievement

in mathematics and science and with national economic development.

As with Lynn's and Tatu Vanhanen's book IQ and Global Inequality, the book was published

by Washington Summit Publishers.[8]

Contents

 [hide]

1 Overview

2 Reception

o 2.1 Criticism

3 See also

4 References

[edit]Overview

Average IQ of indigenous populations according to Lynn (2006)[9]

Lynn devotes a chapter to the data on each of the nine genetic clusters or population groups identified in

previous genetic cluster analysis, which Lynn regards as races. The book subsequently defends the

reliability and validity of the measures, concluding that, though additional evidence may be required to

confirm some of the racial IQ estimates, that they correlate highly with performance in international

studies of achievement in mathematics and science and with national economic development.

[edit]Reception

Three reviews of Race Differences in Intelligence have been published in the scholarly literature.[10][11][12] At

least two of these are written by persons who, like Lynn, are connected to the Pioneer Fund.

[edit]Criticism

A review by Nicholas Mackintosh, Emeritus Professor in the Department of Experimental

Psychology,University of Cambridge, criticizes Lynn's occasional manipulation of data, some of it

originally collected by the reviewer, from which distorted conclusions have been drawn. Mackintosh

expresses astonishment that Lynn infers elsewhere that Kalahari bushmen, with an average measured IQ

of 54, should be regarded as mentally retarded; and that an 8 year old European child with the equivalent

mental age would have no problems surviving in the same desert environment. He concludes:[13]

"Much labour has gone into this book. But I fear it is the sort of book that gives IQ testing a bad name. As

a source of references, it will be useful to some. As a source of information, it should be treated with

some suspicion. On the other hand, Lynn's preconceptions are so plain, and so pungently expressed, that

many readers will be suspicious from the outset."

In a 2008 review of the data used in Lynn's book, Hunt and Wittmann[14] write:

"The majority of the data points were based upon convenience rather than representative samples. Some

points were not even based on residents of the country. For instance, the “data point” for Suriname was

based on tests given to Surinamese who had migrated to the Netherlands, and the “data point”

for Ethiopia was based on the IQ scores of a highly selected group that had emigrated to Israel and, for

cultural and historical reasons, was hardly representative of the Ethiopian population. The data point for

Mexico was based upon a weighted averaging of the results of a study of “Native American

and Mestizo children in southern Mexico” with result of a study of residents of Argentina. Upon reading

the original reference, we found that the “data point” that Lynn and Vanhanen used for the lowest IQ

estimate, Equatorial Guinea, was actually the mean IQ of a group of Spanish children in a home for the

developmentally disabled in Spain. Corrections were applied to adjust for differences in IQ across cohorts

(the“Flynn” effect), on the assumption that the same correction could be applied internationally, without

regard to the cultural or economic development level of the country involved. While there appears to be

rather little evidence on cohort effect upon IQ across the developing countries, one study in Kenya (Daley,

Whaley, Sigman, Espinosa, & Neumann, 2003[15]) shows a substantially larger cohort effect than is

reported for developed countries."

[edit]See also

Richard Lynn (born 1930) is a British Professor Emeritus of Psychology at the University of Ulster [1]

[2] who is known for his views on racialand ethnic differences.[3] Lynn says that there are race and sex

differences in intelligence.

Lynn was educated at Bristol Grammar School and Cambridge University in England. He has worked as

lecturer in psychology at theUniversity of Exeter, and as professor of psychology at the Economic and

Social Research Institute, Dublin, and at the University of Ulster at Coleraine. He has written or co-written

more than 11 books and 200 journal articles spanning five decades. Two of his recent books are

ondysgenics and eugenics.

In the late 1970s, Lynn wrote that he found a higher average IQ in East Asians compared to Whites (5

points higher in his meta-analysis). In 1990, he proposed that the Flynn effect – an observed year-on-year

rise in IQ scores around the world – could possibly be explained by improved nutrition, especially in early

childhood.

Like much of the research in race and intelligence, Lynn's research is controversial. He is cited in the

book The Bell Curve. He was also one of the 52 scientists who signed "Mainstream Science on

Intelligence", an opinion piece in the Wall Street Journal.[4] He sits on the editorial boards of the

journals Intelligence and Personality and Individual Differences.[5] He also sits on the boards of

the Pioneer Fund, and of the Pioneer-supported journal Mankind Quarterly.

Contents

 [hide]

1 Early life and career

2 Race differences in intelligence

o 2.1 Past works

o 2.2 More recent works

o 2.3 Immigration

3 Sex differences in intelligence

4 Dysgenics and eugenics

5 The Pioneer Fund

6 Criticism

7 Notes

8 References

9 Further reading

10 External links

[edit]Early life and career

Lynn was educated at Bristol Grammar School and Cambridge University in England.[2] He has worked as

lecturer in psychology at the University of Exeter, and as professor of psychology at the Economic and

Social Research Institute, Dublin, and at the University of Ulster at Coleraine.

[edit]Race differences in intelligence

[edit]Past works

Lynn's psychometric studies were cited in the 1994 book The Bell Curve and were criticized as part of the

controversy surrounding that book.[citation needed] His article, "Skin color and intelligence in African

Americans," 2002, Population and Environment, concludes that lightness of skin color in African-

Americans is positively correlated with IQ, which he claims derives from the higher proportion of

Caucasian admixture.[6]

In IQ and the Wealth of Nations (2002),[7] Lynn and co-author Tatu Vanhanen (University of Helsinki)

argue that differences in national income (in the form of per capita gross domestic product) correlate with,

and can be at least partially attributed to, differences in average national IQ. One study following up on

Lynn and Vanhanen's hypothesis, "Temperature, skin color, per capita income, and IQ: An international

perspective" (Templer and Arikawa, 2006),[8][9] is listed as the most downloaded article

in Intelligence at ScienceDirect (Jan - March 2006).[10]

[edit]More recent works

Race Differences in Intelligence

Lynn's 2006 Race Differences in Intelligence: An Evolutionary Analysis [11]  is the largest review of the

global cognitive ability data. The book organizes the data by nine global regions,[verification needed] surveying

620 published studies from around the world, with a total of 813,778 tested individuals.

Lynn's meta-analysis lists the average IQ scores of East

Asians (105), Europeans (99), Inuit (91), Southeast Asians and Amerindians each (87), Pacific

Islanders(85), Middle Easterners (including South Asians and North Africans) (84), East and West

Africans (67), Australian Aborigines (62) and Bushmen and Pygmies (54).[12][13][14]

Lynn has previously argued that nutrition is the best supported environmental explanation for variation in

the lower range,[15] and a number of other environmental explanations have been advanced

(see below). Ashkenazi Jews average 107-115 in the U.S. and Britain, but lower in Israel.[16] Lynn argues

the surveyed studies have high reliability in the sense that different studies give similar results, and

high validity in the sense that they correlate highly with performance in international studies of

achievement in mathematics and science and with national economic development.

Following Race Differences in Intelligence, Lynn co-authored a further paper[17] along the lines of IQ and

the Wealth of Nations with Jaan Mikk (Šiauliai University, Lithuania) - in press in Intelligence - and has co-

authored a second book on the subject with Vanhanen, IQ and Global Inequality, which was published

later in 2006.[18]

Lynn's most recent book is The Global Bell Curve, published in June 2008.[19] In describing the book, Lynn

says "it concludes that IQ is a key explanatory variable for the social sciences, analogous to gravity in

physics."[20] It was reviewed by J. Philippe Rushton around the time of publication.[21]

Further information: Race_and_intelligence#IQ_differences_outside_of_the_USA

In a recent paper in 2010 about IQ in Italy,[22] Lynn concludes that IQs are highest in the north (103

in Friuli–Venezia Giulia) and lowest in the south (89 in Sicily) and highly correlated with average incomes,

and with stature, infant mortality, literacy and education. According to him "the lower IQ in southern Italy

may be attributable to genetic admixture with populations from the Near East and North Africa". In the

same way, he thinks that this explanation "also accounts for the IQs of around 90 for several countries in

the Balkans whose populations are of partly European and partly Near Eastern origin".

[edit]Immigration

Lynn has spoken against immigration in Britain at a 2000 American Renaissance magazine sponsored

conference, citing problems of unemployment, crime, illegitimacy, and low IQ, considering African and

African-Caribbean immigants to perform worse in these measures than Indian and Chinese immigrants.

[23] Lynn spoke on his book IQ and the Wealth of Nationsat a 2002 American Renaissance conference.[24]

[edit]Sex differences in intelligence

Lynn's research correlating brain size and reaction time with measured intelligence led him to the problem

that men and women have different size brains in proportion to their bodies, but consensus for the last

hundred years has been that the two sexes perform equally on cognitive ability tests. In 1994, Lynn

concluded in a meta-analysis that an IQ difference of roughly 4 points does appear from age 16 and

onwards, but detection of this had been complicated by the faster rate of maturation of girls up to that

point, which compensates for the IQ difference. This reassessment of male-female IQ has been bolstered

by Paul Irwing's meta-analyses in 2004 and 2005 which conclude a difference of 4.6 to 5 IQ points

(see BBC coverage). Irwing finds no evidence that this is due primarily to the male advantage in spatial

visualization, and concludes that some research previously presented to show that there are no sex

differences actually shows the opposite. However, Lynn and Irwing's findings are not without controversy.

[25]

[edit]Dysgenics and eugenics

This section may be too long to read and navigate comfortably. Please consider moving more of the content into sub-articles and using this article for a summary of the key points of the subject. (March 2009)

Dysgenics

In Dysgenics: Genetic Deterioration in Modern Populations, Lynn reviews [26] the history of eugenics, from

the early writings of Bénédict Morel and Francis Galton through the rise of eugenics in the early 20th

century and its subsequent collapse. He identifies three main concerns of eugenicists, such as himself:

deterioration in health, intelligence and conscientiousness. Lynn asserts that natural selection in pre-

industrial societies favored traits such as intelligence and character but no longer do so in modern

societies. He argues that due to the advance of medicine, selection against those with poor genes for

health was relaxed.

Regarding intelligence, Lynn examines sibling studies. Lynn concludes that the tendency of children with

a high number of siblings to be the least intelligent is evidence of dysgenic fertility. Lynn concedes that

there has been a genuine increase in phenotypic intelligence (see Flynn effect), but argues that this is

caused by environmental factors and is masking a decline in genotypic intelligence.

Lynn points to evidence that those with greater educational achievement have fewer children, while

children with lower IQ come from larger families [27] as primary evidence that intelligence and fertility are

negatively correlated. Continuing the theme of correlates of fertility, socioeconomic status appears to

have a negative effect on fertility, which Lynn thinks is because there is increasingly ineffective use

of contraception with declining socioeconomic class. Regarding intelligence, Lynn agrees with Lewis

Terman’s comment in 1922 that “[t]he children of successful and cultivated parents test higher than

children from wretched and ignorant homes for the simple reason that their heredity is better”.[citation needed]

Lynn goes on to present evidence that socioeconomic status is negatively correlated with indicators of

conscientiousness such as work ethic, moral values and crime. Next the geneticbasis of differences in

conscientiousness is discussed, and Lynn concludes that twin studies provide evidence of a

high heritability for the trait. The less conscientious, such as criminals, have more offspring.

While most of the book discusses evidence for dysgenics in developed countries, Lynn acknowledges

that it is less strong in developing countries, but concludes that “dysgenic fertility [...] is a worldwide

phenomenon of modern populations” (p. 196).

Lynn concludes with an examination of counter-arguments. These include that the traits discussed are

not genetically determined, that intelligence and fertility can be inversely related without dysgenics, that

socioeconomic classes do not differ genetically, and that there is no such thing as a ‘bad gene’. These

arguments are dismissed, and Lynn asserts that these trends represent a serious problem. Finally, he

expresses support for eugenics, which is the subject of his next book, Eugenics: A Reassessment.[28]

A review of Dysgenics by W.D. Hamilton, FRS, Royal Society Research Professor in evolutionary

biology at the University of Oxford, was published posthumously in 2000.[29] In this lengthy review, written

according to the author in "rambling essay format", Hamilton writes that Lynn, "discussing the large bank

of evidence that still accumulates on heritability of aptitudes and differentials of fertility, shows in this book

that almost all of the worries of the early eugenicists were well-founded, in spite of the relative paucity of

their evidence at the time"; in the second half of the review, several directions not covered in Lynn's book

are explored.

Another review of Dysgenics was written in 2002 by N.J. Mackintosh, FRS, Emeritus Professor of

Experimental Psychology in the University of Cambridge.[30] Mackintosh writes that, "with a cavalier

disregard for political correctness, he argues that the ideas of the eugenecists were correct and that we

ignore them at our peril." While recognizing that the book provides a valuable and accurate source of

information, he criticizes Lynn for "not fully acknowledg[ing] the negative relationship between social class

and education on the one hand, and infant mortality and life expectancy on the other." He calls into

question Lynn's interpretation of data. He also points out that according to Lynn's reading of the theory of

natural selection, "if it is true that those with lower IQ and less education are producing more offspring,

then they are fitter than those of higher IQ and more education"; he writes that, on the contrary, the

eugenecists' arguments rest not as Lynn suggests on some "biological imperative, but rather on a

particular set of value judgements."

In Eugenics: A Reassessment (2001),[28] Lynn argues that embryo selection as a form of standard

reproductive therapy would raise the average intelligence of the population by 15 IQ points in a single

generation (p. 300). If couples produce a hundred embryos, he argues, the range in potential IQ would be

around 15 points above and below the parents' IQ. Lynn argues this gain could be repeated each

generation, eventually stabilizing the population's IQ at a theoretical maximum of around 200 after as little

as six or seven generations.

Eugenics received praise in the American Psychological Association Review of Books (Lykken 2004) as

"[an] excellent, scholarly book ...one cannot reasonably disagree with him on any point unless one can

find an argument he has not already refuted.", as well as by the journal Nature [31]  as a "comprehensive

histor[y]" and a welcome one, "given the importance of the topic" of dysgenic trends.

[edit]The Pioneer Fund

Lynn currently serves on the board of directors of the Pioneer Fund, and is also on the editorial board of

the Pioneer-supported journal Mankind Quarterly, both of which have been the subject of controversy for

their dealing with race and intelligence and eugenics, and have been accused of racism. Lynn's Ulster

Institute for Social Research received $609,000 in grants from the Pioneer Fund between 1971 and 1996.

[32]

Lynn's 2001 book The Science of Human Diversity: A History of the Pioneer Fund[33] is a history and

defense of the fund, in which he argues that, for the last sixty years, it has been "nearly the only non-profit

foundation making grants for study and research into individual and group differences and the hereditary

basis of human nature ... Over those 60 years, the research funded by Pioneer has helped change the

face of social science."

[edit]Criticism

Lynn's review work on global racial differences in cognitive ability has been cited for misrepresenting the

research of other scientists, and has been criticized for unsystematic methodology and distortion.

Many of the data points in Lynn's book IQ and the Wealth of Nations were not based on residents of the

named countries. The datum for Suriname was based on tests given to Surinamese who had emigrated

to the Netherlands, and the datum for Ethiopia was based on the IQ scores of a highly selected group that

had emigrated to Israel, and, for cultural and historical reasons, was hardly representative of the

Ethiopian population. The datum for Mexico was based on a weighted averaging of the results of a study

of “Native American andMestizo children in Southern Mexico” with results of a study of residents

of Argentina.[34]

The datum that Lynn and Vanhanen used for the lowest IQ estimate, Equatorial Guinea, was the mean IQ

of a group of Spanish children in a home for the developmentally disabled inSpain.[35] Corrections were

applied to adjust for differences in IQ cohorts (the “Flynn” effect) on the assumption that the same

correction could be applied internationally, without regard to the cultural or economic development level of

the country involved. While there appears to be rather little evidence on cohort effect upon IQ across the

developing countries, one study inKenya (Daley, Whaley, Sigman, Espinosa, & Neumann, 2003) shows a

substantially larger cohort effect than is reported for developed countries (p.?)[34]

In a critical review of The Bell Curve, psychologist Leon Kamin faulted Lynn for disregarding scientific

objectivity, misrepresenting data, and for racism.[36] Kamin argues that the studies of cognitive ability of

Africans in Lynn's meta-analysis cited by Herrnstein and Murray show strong cultural bias. Kamin also

reproached Lynn for concocting IQ values from test scores that have no correlation to IQ.[37] Kamin also

notes that Lynn excluded a study that found no difference in White and Black performance, and ignored

the results of a study which showed Black scores were higher than White scores.[38]

Journalist Charles Lane criticized Lynn's methodology in his New York Review of Books article "The

Tainted Sources of 'The Bell Curve'" (1994),[39] to which then Pioneer Fund presidentHarry F.

Weyher replied.[40]

Nature versus nurtureFrom Wikipedia, the free encyclopedia

The nature versus nurture debate concerns the relative importance of an individual's innate qualities

("nature", i.e. nativism, or innatism) versus personal experiences ("nurture", i.e.empiricism or behaviorism)

in determining or causing individual differences in physical and behavioral traits.

"Nature versus nurture" in its modern sense was coined[1][2][3] by the English Victorian polymath Francis

Galton in discussion of the influence of heredity and environment on social advancement, although the terms

had been contrasted previously, for example by Shakespeare (in his play, The Tempest: 4.1). Galton was

influenced[4] by the book The Origin of Species written by his cousin, Charles Darwin. The concept embodied in

the phrase has been criticized[3][4] for its binary simplification of two tightly interwoven parameters, as for

example an environment of wealth, education and social privilege are often historically passed to genetic

offspring.

The view that humans acquire all or almost all their behavioral traits from "nurture" is known as tabula

rasa ("blank slate"). This question was once considered to be an appropriate division of developmental

influences, but since both types of factors are known to play such interacting roles in development, many

modern psychologists consider the question naive - representing an outdated state of knowledge.[5][6][6][7]

[8] Psychologist Donald Hebb is said to have once answered a journalist's question of "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?"[9][10][11][12] That is, the idea that either nature or nurture explains a creature's behaviour is a

sort of single cause fallacy.

In the social and political sciences, the nature versus nurture debate may be contrasted with the structure

versus agency debate (i.e. socialisation versus individual autonomy). For a discussion of nature versus nurture

in language and other human universals, see also psychological nativism.

Contents

 [hide]

1     Scientific approach   

2     Heritability estimates   

3     Interaction of genes and environment   

4     IQ debate   

5     Personality traits   

o 5.1      Advanced techniques   

6     Moral difficulties   

7     Philosophical difficulties   

o 7.1      Are the traits real?   

o 7.2      Biological determinism   

o 7.3      Is the problem real?   

8     Myths about identity   

9     History of the nature versus nurture debate   

10      See also   

11      References   

[edit]Scientific approach

To disentangle the effects of genes and environment, behavioral geneticists perform adoption and twin

studies. Behavioral geneticists do not generally use the term "nurture" to explain that portion of the variance for

a given trait (such as IQ or the Big Five personality traits) that can be attributed to environmental effects.

Instead, two different types of environmental effects are distinguished: shared family factors (i.e., those shared

by siblings, making them more similar) and nonshared factors (i.e., those that uniquely affect individuals,

making siblings different). To express the portion of the variance due to the "nature" component, behavioral

geneticists generally refer to the heritability of a trait.

With regard to the Big Five personality traits as well as adult IQ in the general U.S. population, the portion of

the overall variance that can be attributed to shared family effects is often negligible.[13] On the other hand, most

traits are thought to be at least partially heritable. In this context, the "nature" component of the variance is

generally thought to be more important than that ascribed to the influence of family upbringing.

In her Pulitzer Prize-nominated book The Nurture Assumption, author Judith Harris argues that "nurture," as

traditionally defined in terms of family upbringing does not effectively explain the variance for most traits (such

as adult IQ and the Big Five personality traits) in the general population of the United States. On the contrary,

Harris suggests that either peer groups or random environmental factors (i.e., those that are independent of

family upbringing) are more important than family environmental effects.[14][15]

Although "nurture" has historically been referred to as the care given to children by the parents, with the mother

playing a role of particular importance, this term is now regarded by some as any environmental (not genetic)

factor in the contemporary nature versus nurture debate. Thus the definition of "nurture" has expanded to

include influences on development arising from prenatal, parental, extended family, and peer experiences, and

extending to influences such as media, marketing, and socio-economic status. Indeed, a substantial source of

environmental input to human nature may arise from stochastic variations in prenatal development.[16][17]^88

[edit]Heritability estimates

This chart illustrates three patterns one might see when studying the influence of genes and environment on traits in

individuals. Trait A shows a high sibling correlation, but little heritability (i.e. high shared environmental variance c2; low

heritability h2). Trait B shows a high heritability since correlation of trait rises sharply with degree of genetic similarity. Trait C

shows low heritability, but also low correlations generally; this means Trait C has a high nonshared environmental

variance e2. In other words, the degree to which individuals display Trait C has little to do with either genes or broadly

predictable environmental factors—roughly, the outcome approaches random for an individual. Notice also that even

identical twins raised in a common family rarely show 100% trait correlation.

While there are many examples of single-gene-locus traits, current thinking in biology discredits the notion that

genes alone can determine most complex traits. At the molecular level, DNA interacts with signals from other

genes and from the environment. At the level of individuals, particular genes influence the development of a

trait in the context of a particular environment. Thus, measurements of the degree to which a trait is influenced

by genes versus environment will depend on the particular environment and genes examined. In many cases, it

has been found that genes may have a substantial contribution, including psychological traits such as

intelligence and personality.[18] Yet these traits may be largely influenced by environment in other

circumstances, such as environmental deprivation.

A researcher seeking to quantify the influence of genes or environment on a trait needs to be able to separate

the effects of one factor away from that of another. This kind of research often begins with attempts to calculate

the heritability of a trait. Heritability quantifies the extent to which variation among individuals in a trait is due to

variation in the genes those individuals carry. In animals where breeding and environments can be controlled

experimentally, heritability can be determined relatively easily. Such experiments would be unethical for human

research. This problem can be overcome by finding existing populations of humans that reflect the

experimental setting the researcher wishes to create.

One way to determine the contribution of genes and environment to a trait is to study twins. In one kind of

study, identical twins reared apart are compared to randomly selected pairs of people. The twins share identical

genes, but different family environments. In another kind of twin study, identical twins reared together (who

share family environment and genes) are compared to fraternal twins reared together (who also share family

environment but only share half their genes). Another condition that permits the disassociation of genes and

environment is adoption. In one kind of adoption study, biological siblings reared together (who share the same

family environment and half their genes) are compared to adoptive siblings (who share their family environment

but none of their genes).

Some have pointed out that environmental inputs affect the expression of genes (see the article

on epigenetics). This is one explanation of how environment can influence the extent to which a genetic

disposition will actually manifest.[citation needed]The interactions of genes with environment, called gene-environment

interaction, are another component of the nature-nurture debate. A classic example of gene-environment

interaction is the ability of a diet low in the amino acid phenylalanine to partially suppress the genetic

disease phenylketonuria. Yet another complication to the nature-nurture debate is the existence of gene-

environment correlations. These correlations indicate that individuals with certain genotypes are more likely to

find themselves in certain environments. Thus, it appears that genes can shape (the selection or creation of)

environments. Even using experiments like those described above, it can be very difficult to determine

convincingly the relative contribution of genes and environment.

[edit]Interaction of genes and environment

This section does not cite any references or sources.Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (June 2008)

In only a very few cases is it fair to say that a trait is due almost entirely to nature, or almost entirely to nurture.

[citation needed] In the case of most diseases now strictly identified as genetic, such as Huntington's disease, there is

a better than 99.9% correlation between having the identified gene and the disease and a similar correlation for

not having either. On the other hand, Huntington's animal models live much longer or shorter lives depending

on how they are cared for (animal husbandry).

At the other extreme, traits such as native language are environmentally determined: linguists have found that

any child (if capable of learning a language at all) can learn any human language with equal facility. With

virtually all biological and psychological traits, however, genes and environment work in concert,

communicating back and forth to create the individual.

But even in the most clear-cut cases, extreme genetic or environmental conditions can overrule the other – if a

child is born mute due to a genetic mutation, it will not learn to speak any language regardless of the

environment; similarly, someone who is practically certain to eventually develop Huntington's disease

according to their genotype may die in an unrelated accident (an environmental event) long before the disease

will manifest itself.

Examples of environmental, interactional, and genetic traits are:

Predominantly Environmental Interactional Predominantly Genetic

Specific language Height Blood type

Specific religion Weight Eye color

Skin color

The "two buckets" view of heritability.

More realistic "homogenous mudpie" view of heritability.

Steven Pinker (2004) likewise described several examples:

concrete behavioral traits that patently depend on content provided by the home or culture—which

language one speaks, which religion one practices, which political party one supports— are not

heritable at all. But traits that reflect the underlying talents and temperaments —how proficient with

language a person is, how religious, how liberal or conservative— are partially heritable.

When traits are determined by a complex interaction of genotype and environment it is possible to

measure the heritability of a trait within a population. However, many non-scientists who encounter a

report of a trait having a certain percentage heritability imagine non-interactional, additive contributions of

genes and environment to the trait. As an analogy, some laypeople may think of the degree of a trait

being made up of two "buckets", genes and environment, each able to hold a certain capacity of the trait.

But even for intermediate heritabilities, a trait is always shaped by both genetic dispositions and the

environments in which people develop, merely with greater and lesser plasticities associated with these

heritability measures.

Heritability measures always refer to the degree of variation between individuals in a population. These

statistics cannot be applied at the level of the individual. It is incorrect to say that since the heritability

index of personality is about .6, you got 60% of your personality from your parents and 40% from the

environment. To help to understand this, imagine that all humans were genetic clones. The heritability

index for all traits would be zero (all variability between clonal individuals must be due to environmental

factors). And, contrary to erroneous interpretations of the heritibility index, as societies become more

egalitarian (everyone has more similar experiences) the heritability index goes up (as environments

become more similar, variability between individuals is due more to genetic factors).

A highly genetically loaded trait (such as eye color) still assumes environmental input within normal limits

(a certain range of temperature, oxygen in the atmosphere, etc.). A more useful distinction than "nature

vs. nurture" is "obligate vs. facultative" —under typical environmental ranges, what traits are more

"obligate" (e.g., the nose —everyone has a nose) or more "facultative" (sensitive to environmental

variations, such as specific language learned during infancy). Another useful distinction is between traits

that are likely to be adaptations (such as the nose) and those that are byproducts of adaptations (such

the white color of bones), or are due to random variation (non-adaptive variation in, say, nose shape or

size).

[edit]IQ debate

Main article: Heritability of IQ

Evidence suggests that family environmental factors may have an effect upon childhood IQ, accounting

for up to a quarter of the variance. On the other hand, by late adolescence this correlation disappears,

such that adoptive siblings are no more similar in IQ than strangers.[19]

Moreover, adoption studies indicate that, by adulthood, adoptive siblings are no more similar in IQ than

strangers (IQ correlation near zero), while full siblings show an IQ correlation of 0.6. Twin studies

reinforce this pattern: monozygotic (identical) twins raised separately are highly similar in IQ (0.74), more

so than dizygotic (fraternal) twins raised together (0.6) and much more than adoptive siblings (~0.0).[20]

[edit]Personality traits

Personality is a frequently cited example of a heritable trait that has been studied in twins and adoptions.

Identical twins reared apart are far more similar in personality than randomly selected pairs of people.

Likewise, identical twins are more similar than fraternal twins. Also, biological siblings are more similar in

personality than adoptive siblings. Each observation suggests that personality is heritable to a certain

extent. However, these same study designs allow for the examination of environment as well as genes.

Adoption studies also directly measure the strength of shared family effects. Adopted siblings share only

family environment. Unexpectedly, some adoption studies indicate that by adulthood the personalities of

adopted siblings are no more similar than random pairs of strangers. This would mean that shared family

effects on personality are zero by adulthood. As is the case with personality, non-shared environmental

effects are often found to out-weigh shared environmental effects. That is, environmental effects that are

typically thought to be life-shaping (such as family life) may have less of an impact than non-shared

effects, which are harder to identify. One possible source of non-shared effects is the environment of pre-

natal development. Random variations in the genetic program of development may be a substantial

source of non-shared environment. These results suggest that "nurture" may not be the predominant

factor in "environment"[citation needed].

[edit]Advanced techniques

The power of quantitative studies of heritable traits has been expanded by the development of new

techniques. Developmental genetic analysis examines the effects of genes over the course of a human

lifespan. For example, early studies of intelligence, which mostly examined young children, found

that heritability measures 40 to 50 percent. Subsequent developmental genetic analyses found that

variance attributable to additive environmental effects is less apparent in older individuals,[21][22][23] with

estimated heritability of IQ being higher than that in adulthood. However, the high IQ heritability estimates

are derived with questionable methodologies, according the work by Peter Schönemann.[24].

Another advanced technique, multivariate genetic analysis, examines the genetic contribution to several

traits that vary together. For example, multivariate genetic analysis has demonstrated that the genetic

determinants of all specific cognitive abilities (e.g., memory, spatial reasoning, processing speed) overlap

greatly, such that the genes associated with any specific cognitive ability will affect all others. Similarly,

multivariate genetic analysis has found that genes that affect scholastic achievement completely overlap

with the genes that affect cognitive ability.

Extremes analysis, examines the link between normal and pathological traits. For example, it is

hypothesized that a given behavioral disorder may represent an extreme of a continuous distribution of a

normal behavior and hence an extreme of a continuous distribution of genetic and environmental

variation. Depression, phobias, and reading disabilities have been examined in this context.

For a few highly heritable traits, some studies have identified loci associate with variance in that trait in

some individuals. For example, research groups have identified loci that are associated

with schizophrenia (Harrison and Owen, 2003) in subsets of patients with that diagnosis.

[edit]Moral difficulties

Some observers believe that modern science tends to give too much weight to the nature side of the

argument, in part because of social consciousness. Historically, much of this debate has had undertones

of racist and eugenicist policies — the notion of race as a scientific truth has often been assumed as a

prerequisite in various incarnations of the nature versus nurture debate. In the past, heredity was often

used as "scientific" justification for various forms of discrimination and oppression along racial and class

lines. Works published in theUnited States since the 1960s that argue for the primacy of "nature" over

"nurture" in determining certain characteristics, such as The Bell Curve, have been greeted with

considerable controversy and scorn.[citation needed]

[edit]Philosophical difficulties

[edit]Are the traits real?

It is sometimes a question whether the "trait" being measured is even a real thing. Much energy has been

devoted to calculating the heritability of intelligence (usually the I.Q., orintelligence quotient), but there is

still some disagreement as to what exactly "intelligence" is.

[edit]Biological determinism

If genes do contribute substantially to the development of personal characteristics such as intelligence

and personality, then many wonder if this implies that genes determine who we are. See Genetic

determinism and Biological determinism.

[edit]Is the problem real?

Many scientists feel that the very question opposing nature to nurture is a fallacy. Already in 1951, Calvin

Hall in his seminal chapter[25] remarked that the discussion opposing nature and nurture was fruitless. If

an environment is changed fundamentally, then the heritability of a character changes, too. Conversely, if

the genetic composition of a population changes, then heritability will also change. As an example, we

may use phenylketonuria (PKU), which causes brain damage and progressive mental retardation. PKU

can be treated by the elimination of phenylalanine from the diet. Hence, a character (PKU) that used to

have a virtually perfect heritability is not heritable any more if modern medicine is available (the

actualallele causing PKU would still be inherited, but the phenotype PKU would not be expressed any

more). Similarly, within, say, an inbred strain of mice, no genetic variation is present and every character

will have a zero heritability. If the complications of gene-environment interactions and correlations (see

above) are added, then it appears to many that heritability, the epitome of the nature-nurture opposition,

is "a station passed".[26]

[edit]Myths about identity

Within the debates surrounding cloning, for example, is the far-fetched contention that a Jesus or

a Hitler could be "re-created" through genetic cloning. Current thinking finds this largely inaccurate, and

discounts the possibility that the clone of anyone would grow up to be the same individual due to

environmental variation. For example, like clones, identical twins are genetically identical, and unlike the

hypothetical clones share the same family environment, yet they are not identical in personality and other

traits.

[edit]History of the nature versus nurture debate

Further information: Empiricism and Tabula rasa

Traditionally, human nature has been thought of as not only inherited but divinely ordained.[citation

needed] Whole ethnic groups were considered to be, by nature, superior or inferior. Since the late Middle

Ages, intellectuals increasingly attributed differences among races, classes and genders to socialization

(nurture), rather than to innate qualities (nature).[citation needed] In the 20th century, the Nazis pursued an

agenda based on the concept of human nature as defined by one's race. The Communists, on the other

hand, largely followed Marx's lead in defining the human identity as subject to social structures, not

nature. In scientific circles, this conflict led to ongoing controversy of sociobiology and evolutionary

psychology.[citation needed]

[edit]See also

Look 

up nurture in Wiktionary, the 

free dictionary.

behavioural genetics

communibiology

developmental systems theory

diathesis–stress model

differential susceptibility hypothesis

epigenetic theory

genetic determinism

heritability of IQ

The Nurture Assumption  (book)

race and crime in the United States

David Reimer

social determinism

structure and agency