In recent interviews and a new book, Nobel-prizewinning scientists James Watson has made racist statements to the effect that blacks are less intelligent than whites, that equal powers of reason among racial groups was a delusion, that Africans have lower intelligence, that anyone who has had to deal with black employees knows they are not equal, as well as earlier statements relating sex drive to skin color, as reported by many publications, including the Oct 19 San Francisco Chronicle.
Watson is not an isolated racist nut, as portrayed in most accounts. Watson is one more boxcar on a whole train of academic racists that business-inspired thinktanks have been brought out during times when business and government were attacking workers in general: Arthur Jenson, William Shockley, Richard Herrnstein, Charles Murray, all were promoted and had to be beaten back into the woodwork by anti-racist students, professors, and researchers.
Now, the US is preparing for decades-long war in the Mideast and probably with China, years of economically painful “recovery” are giving way to financial meltdown, the wealth gap is as high as the 1920s and is increasing, and 70 million will retire in the next decade with longer life expectancies and high rates of expensive chronic disease. These are accompanied by stepped-up attacks on minorities such as Katrina; worsening gaps in health, education, and income; increased police harassment and killing of youth; gang injunctions as a form of state-sanctioned racial profiling; ICE raids, deportations, and separation of immigrant families; and nooses in Jena and around the country. So it should hardly be surprising to see a Nobel Prize-winner and head of a prestigious genetics lab writing a racist book and traveling around Europe and the US promoting his ideas.
The essay below, written by respected experts in genetics, refutes Watson’s claims about intelligence, genetics, and biological determinism. Following that, another essay exposes the fallacies of determining ancestry through genetic testing. For the larger issues of how the ruling class uses racism to exploit and suppress the working class, and the historical role of academics, there is a longer piece, “Racism, Intelligence, and the Working Class,” written from a communist perspective.
Long before they enter school, children are judged on their relative ability to master such cognitive tasks as solving puzzles, learning the alphabet, and counting. Many parents encourage their children to succeed on such tasks both in and out of school, demonstrating pleasure and disappointment based on their performances. Those who go on to do well on school tasks such as reading and science can expect to be rewarded with more opportunities than those who do not. It is no wonder, then, that children sense that their intellectual capabilities are bound to their value as individuals.
Our society has developed various means for the formal evaluation of intelligence. Since the development of the first “intelligence” test less than one hundred years ago, the “intelligence quotient,” or IQ, has become a household term meant to reflect the range and limits of a person’s cognitive potential. This widespread use is echoed by the increase of achievement testing nationwide. For example the company, Kaplan Test Prep and Admissions ran an advertisement recently that read, “higher score, brighter future ,” which reflects the current cultural attitude about testing.
However, even experts have not been able to agree upon which abilities are most relevant to overall intelligence. The American Psychological Association’s Report on Intelligence published in 1995  highlighted the lack of consensus among scientists regarding the term and the state of intelligence testing. Citing a study by Robert Sternberg and Douglas Detterman,  the task force reported, “when two dozen prominent theorists were recently asked to define intelligence, they gave two dozen somewhat different definitions.” While a small group of psychologists maintain that intelligence can be measured by IQ tests, others have sought to broaden our notion of what the term means.
Much of the current excitement about testing arose from a push to address gaps in achievement among various groups. Many researchers believe that disparities in performance result from economic and social factors. Others conclude that these gaps are the result of innate biological differences. Charles Murray and Richard Herrnstein, authors of the The Bell Curve , a controversial tome published in 1994, argue that achievement differences are not the result of unequal treatment, access to educational resources, or socio-economic status, but of genetic differences between individuals or groups. The most controversial claim made in the book lies in the analysis of how race contributes to these differences. The Bell Curve manipulates statistics to show that programs such as Affirmative Action  and Head Start  don’t work, while ignoring data from other studies that suggests otherwise.
The use of flawed science to help present a case for accepting the status quo is not new. Attempts to link intelligence to social hierarchies were made throughout the nineteenth and twentieth centuries. These have not been substantiated by science. Attempts to find a gene or set of markers implicated in the development or outcome of human intelligence have not succeeded, since no one understands how much of a role biology plays in human intelligence. The direction of current research is based on a model in which a single number on a linear scale defines the learning potential of an individual. Several psychologists who have questioned this approach have developed alternative models that attempt to expand the definition of intelligence to include a broader spectrum of abilities. Such models have investigated and described capacities such as creativity, social intelligence, and common sense as key to human adaptation. These include Howard Gardner’s “Theory of Multiple Intelligences ,” Robert Sternberg’s “Triarchic Mind ,” and Daniel Goleman’s “Emotional Intelligence .” These preliminary approaches have received strong positive responses from specialists in the field. In fact, the primary way intelligence tends to be evaluated is based on a scale originally devised for a different purpose.
IQ: A Short History
The modern IQ test is a direct descendant of a measure designed by French psychologist Alfred Binet in 1905 . As Steven Jay Gould points out in The Mismeasure of Man , though Binet originally designed his test to identify students who would need help in school, not as an overall measure of cognitive ability, his scale has come to be regarded as having laid the foundations for modern tests of intelligence. Lewis Terman, a researcher at Stanford University was the first to adapt Binet’s scale, revising and renaming it the “Stanford-Binet” test of intelligence in 1916 . Terman believed that the dissemination of testing would bring to the attention of the government “tens of thousands of defectives” who should be kept from breeding. Thus the birth of modern notions of intelligence was closely tied to the eugenics movement of the same period. From the standpoint of eugenicists of the time, Terman’s test could be used for the purpose of identifying and eliminating from the gene pool, individuals with subnormal potential.
In an effort to underscore the scientific basis of these tests, researcher Charles Spearman developed a model that has come to be known as Spearman’s g , or the general factor of intelligence. Spearman argued that grades or scores on seemingly unrelated tasks, such as arithmetic and reading ability, are highly correlated. These abilities, he argued, combine to form an overall abstract reasoning capacity, or “g,” that can be measured. Ever since, the notion of g has held sway over decades of research on human intelligence.
Beyond statistical correlations, there is no conclusive proof that IQ tests do more than detect who might encounter difficulty with school learning. In our society, school is a pathway to success later in life. Though Spearman and others claim that intelligence is related to success in school, this claim cannot be investigated until intelligence has been properly defined. Still, research into the biology of intelligence continues. Efforts range from genetic research to how inadequate nutrition during early development affects learning. The following is a survey of the current science.
Genetic Research on IQ
No set of genes or gene markers has been conclusively linked to the development of intelligence. Specific genes that have been studied are primarily those believed to be linked to the development of brain size. Yet no link between human brain size and intelligence has been established.
Other theories have been proposed to explain how differences in brain size and structure have evolved. One such theory detailed by British neuroscientist John R. Skoyles in his paper, “Human Evolution Expanded Brains to Increase Expertise Capacity, Not IQ ,” argues that size differences are related to skill development. Skoyles maintains that the human brain increased in size over time due to a need for increased “expertise” or skill capacity associated with highly complex tasks that have varied from culture to culture. He argues that this explains differences in brain size among groups.
Contributing evidence comes from studies on children suffering from severe epilepsy who have had a brain hemisphere removed to prevent debilitating seizures. If removed early enough, half a brain seems to work nearly as well as a whole one. The remaining hemisphere often co-opts the functions previously handled by the missing portion . Data from work with patients suffering from microcephaly, a congenital disorder which results in reduced brain size and function, reveals that though a majority of patients score considerably below average on IQ tests, a small portion test in the normal range . These examples challenge the notion that a person’s brain size determines his or her cognitive ability.
Some genes that have been correlated to g are those associated with Cathepsin D (CTSD) and the cholinergic muscarinic 2 receptor (CHRM2) . But it remains unclear what roles these particular genes play in the development of intelligence, if any. Genetic studies attempting to link genes to IQ have uncovered many “candidates” but little conclusive evidence. Research, at this point, has been restricted to analyzing levels of g and the presence or absence of these candidate genes.
Findings from twin, adoption, and family studies are the most commonly cited forms of evidence for a biological theory of intelligence. These studies compare individuals with very similar DNA (identical twins or related family members) with biologically unrelated children growing up in the same home or with children and their adoptive parents. This method attempts to distinguish traits a person is born with from those influenced by his or her environment. Molecular biologist, Robert Plomin has utilized such studies to estimate the heritability of intelligence at around .50 (50%) of the variance . Other studies utilizing g as a cognitive measure have arrived at similar estimates. Longitudinal studies show that these effects increase with age. The heritability of g appears to rise to about .75 (75%) by late adolescence. One explanation for this shift is that family influences on cognition are deemed to diminish throughout development. Also possible, explains Plomin, is that additional gene expression delayed during childhood may be triggered as cognitive processes develop.
But do these studies provide evidence that intelligence is inherited? Causation has not been determined here. There are two significant problems associated with twin/adoption and family studies. First is the assumption that genetic effects can be separated from environmental effects. This position rests on the “equal environments assumption” (EEA), which posits that the environment of individuals in the same or different homes can be controlled for in such a way that genetic effects can be separated out. There have been serious critiques levied at EEA due to the way adoptive and non-adoptive environments are appraised as being different or alike . Additionally, the idea that genetic and environmental effects are simply additive and work in isolation of one another is false.
Second, a majority of these studies do not account for how IQ outcomes are affected by class differences. Eric Turkheimer, et al. utilized the twin/adoption and family method to show that socioeconomic status modifies heritability of IQ in young children . The study found that in families who subsisted on incomes at or below the poverty line, the heritabilty effects on IQ were close to zero, whereas in affluent families, these effects were quite high. They also found that parental education levels modified both the effects of heritability and environment, increasing the former and decreasing the latter as years of education increased. In cases where adequate nutrition, access to education, protection from exposure to environmental toxins, and similar issues have affected the development of individuals, heritability estimates have been shown to be expressed quite differently.
Another phenomenon that seems to refute current heritability estimates is the “Flynn effect ,” which describes a steady worldwide rise in performance since testing began. A three-point rise in IQ per decade on average has been noted, even when tests have been re-standardized to account for these gains. The reasons for this rise are not known, but one explanation involves children’s need, and the need of people in general, to adapt to the increasing complexity of modern life. Obviously the rise cannot result from genetic mutation as the time frame is too narrow. Rather, the Flynn effect may demonstrate how flexible human cognitive development really is. As successive generations take in greater, and more complex, amounts of information from shifting sources such as television and radio, they learn to process the increase. The phenomenon calls into question the extent to which g is an inborn trait. Members of the American Psychological Association task force underscored in their 1995 report that: “…heritable traits can depend on learning and they may be subject to other environmental effects as well. The value of heritability can change if the distribution of environments (or genes) in the population is substantially altered .”
Environmental Effects on IQ
A wealth of research has identified multiple environmental factors that may contribute to variation in IQ scores. Many studies have focused on variables such as nutrition, exposure to toxic chemicals, family environment, and socio-economic status, and how these might affect test scores.
Quality and years of schooling have been shown to have an effect on IQ scores. For many children, particularly those from low-income backgrounds, school may be the primary transmitter of information. One study by Lee  followed a group of African-American students who were moved from a poor rural school in the south to an urban school with greater resources in Philadelphia. The groups’ average IQ score increased by one-half point each year that they attended the Philadelphia school. Ceci found a positive correlation between years of school attended and IQ scores . His study found that when same-age children enter school a year apart, those with the additional year of school have higher mean scores. These results are borne out in our society. Children who attend poor schools in rural or urban areas tend to score lower on IQ tests than those that have access to a higher quality of education.
A school-based program that has consistently demonstrated success in raising IQ scores is Head Start. The Department of Health and Human Services began implementing this program in 1964 in an effort to assist families with fewer economic resources by providing educational assistance to children from such families who were under the age of five years. Since its inception, Head Start has enrolled over 22 million children in its programs across the United States. Outcomes suggest that major cognitive gains, at least for the short term, result from this intervention. Follow up studies show that children who attended Head Start are less likely to need special education and more likely to finish high school than those who have not enrolled in the program .
Malnutrition during childhood often results in cognitive deficits. A Guatemalan study on undernourished preschoolers showed that those who were given a protein-rich dietary supplement over a ten-year period performed much better on IQ tests than those who did not . There are obvious ethical problems involved in denying undernourished children an available nutritional supplement for the purposes of a study. Yet this data shows that, even though it is not known whether nutrition directly affects IQ, (since undernourished children tend to be less motivated and responsive to adults and therefore less active in their exploration), a child’s food intake clearly is somehow related to her or his ability to learn.
The effects of toxic substances, such as lead and alcohol, on IQ test scores are well known . Children living in impoverished urban environments are at much greater risk for exposure to both. Building codes and zoning laws have reduced lead levels in recent years, but the effects of other toxic chemicals in these environments have not been well studied. Fetal Alcohol Syndrome, a condition resulting from the use of alcohol during pregnancy, leads to a range of deficits in cognitive functions such as attention and memory, as well as IQ .
Studies conducted on children who have been abused and neglected show that this often results in a higher than average rate of psychiatric and cognitive disorders . Even in homes with less extreme conditions, the differences in the use of language and size of vocabulary have been shown to affect scores on verbal IQ tests. Parents’ years of schooling affect the IQ scores of children, as does early exposure to concepts such as counting . Most of the evidence on environmental contributors to intelligence scores and intellectual development show a clear advantage for children who grow up in middle-class or affluent homes. This evidence should be weighted carefully in any discussion regarding between-group differences in IQ.
Between Group Differences in IQ
Some of the debate surrounding the biological basis of IQ focuses on differences in test scores between racial groups. Yet, these differences, such as those between African-Americans, Hispanics, and Whites, are shrinking. In the 1970’s, African-American IQ scores averaged a full standard deviation (15 points) below the average for Whites, with Hispanic scores falling somewhere in between the two averages. Since then, test scores for African-American and Hispanic groups have gradually risen, even outpacing the Flynn effect . This has paralleled score increases on other achievement tests. One study tracked the scores of African-American five-year olds on the math section of the National Assessment of Educational Progress between 1978 and 1990. Results showed substantial gains over the twelve-year period . Improvements like these have been attributed to programs focused on improving socio-economic status for minority groups as well those that have focused more on educational interventions. Unfortunately, despite the evidence, authors such as Herrnstein and Murray maintain that these kinds of efforts are wasted.
We do not yet know how to define human intelligence. Despite this, there is a strong push from some in the scientific community to quantify it. Attempts to describe human intelligence as an inborn trait rest on models like the IQ and Spearman’s g that have not been proven or agreed upon. Even when these models are used as a default, there is a lack of evidence for a genetic link.
Plomin has suggested that it would be useful to administer genetic tests to children to identify those with verbal learning disabilities and other cognitive disorders. He has further suggested that this type of testing occur before a child enters school in order to intervene appropriately prior to enrollment . Based on the currently available data, these suggestions seem premature. Implementing such policies might well result in discrimination by parents, teachers, employers, and institutions, which, in turn, would be likely to affect performance on achievement tests.
Based on findings from current research, further study on brain plasticity and neural development, improvements in learning environments and teaching techniques, and policies which emphasize support for disadvantaged populations are likely to yield more positive outcomes in school achievement. Contrary to what the authors of The Bell Curve suggest, key social policies have demonstrated strong positive effects on IQ scores, particularly for disadvantaged groups.
Unfortunately however, a new educational climate is forming. Increases in all kinds of academic testing have overtaken more balanced approaches to learning. Possibly the largest shift occurred in 2001 with the “No Child Left Behind ” Act implemented by the Bush Administration. Research has shown that self-esteem directly affects motivation to learn. We will continue to see that performance on IQ and other standardized tests has an effect on the way students are treated and on their self esteem. Low scores affect the attitudes of teachers and other adults as well, so that this approach may ensure that students who struggle with testing will end up in classrooms and categories in which they won’t be expected to improve. In this way, performance on tests, rather than helping children to learn and improve, can become self-fulfilling prophecies of failure for both the children and the adults who are expected to teach them.
2 Intelligence: Knowns and Unknowns. Board of Scientific Affairs, American PsychologicalAssociation. Released August 7, 1995.
3 Sternberg, Robert J. and Douglas K. Detterman. (Eds.). 1986. What is intelligence? Contemporary viewpoints on its nature and definition. Norwood, NJ: Ablex.
4 Herrnstein, Richard J. and Charles Murray. 1994. The bell curve: the reshaping of American life by difference in intelligence. New York: Free Press.
5 Affirmative Action information Retrieved on 02 Mar. 2006 at: http://www.infoplease.com/spot/affirmativetimeline1.html#1961
6 Head Start Program information retrieved from the United States Department of Health and Human Services’ Administration for Children and Families website on 02 March, 2006 at: http://www2.acf.dhhs.gov/programs/hsb/
7 Gardner, Howard. 1983. Frames of mind: the theory of multiple intelligences. New York: Basic Books.
8 Sternberg, Robert J. 1986. The triarchic mind: a new theory of human intelligence. New York: Viking.
9 Goleman, Daniel. 1998. Working with emotional intelligence. New York: Bantam Books.
10 Binet, Alfred and Theodore Simon. 1912. A method of measuring the development of the intelligence in young children. Lincoln, IL: Courier Company.
11 Gould, Steven J. 1981/1996. The Mismeasure of Man: the definitive refutation to the argument of ‘the bell curve.’ New York, NY: W.W. Norton & Company.
12 Terman, Lewis, et al. 1917. The Sanford revision extension of the Binet-Simon scale for measuring intelligence. Baltimore, MD: Warwick and York.
13 Spearman, C. 1904. General intelligence objectively determined and measured. American Journal of Psychology. 15: 201-293.
14 Skoyles, J. R. 1999. Human evolution expanded brains to increase expertise capacity, not IQ. Psycoloquy. 10:
15 Battro, Antonio. 2001. Half a brain is enough: the story of Nico. New York, NY: Cambridge University Press.
16 Dorman, C. 1991. Microcephaly and Intelligence. Developmental Medicine and ChildNeurology. 33(3): 267-69.
17 Plomin, R. 2003. Genetics, genes, genomics, and g (guest editorial). Molecular Psychiatry. 8: 1-5.
18 Plomin, R. 2004. Intelligence: genetics, genes, and genomics. Journal of Personality and Social Psychology. 86(1): 112-129.
19 Pam, A.; S. Kemker; C. Ross; and R. Golden. 1996. The equal environments assumption in MZ-DZ twin comparisons: an untenable premise of psychiatric genetics? Acta GeneticaeMedicae et gemellologiae: Twin Research. 45(3): 349-360.
20 Turkheimer, E.; A. Haley; M. Waldron; B. D’Onofrio; and I. Gottesman. 2003. Socioeconomic status modifies heritability of IQ in young children. Psychological Science. 14(6): 623-628.
21 Flynn, J.R. (1981). “The mean IQ of Americans: Massive gains 1932 to 1978.” Psychological Bulletin, Vol. 95, pp. 29-51.
22 “Intelligence: Knowns and Unknowns.” Board of Scientific Affairs, American Psychological Association. Released August 7, 1995.
23 Lee, E.S. (1951). “Negro intelligence and selective migration: A Philadelphia test of the Klineberg hypothesis.” American Sociological Review. Vol. 16, pp. 227-232.
24 Ceci, S. J. 1991. How much does schooling influence general intelligence and its cognitive components? A reassessment of the evidence. Developmental Psychology. 27: 703-722.
25 Consortium for Longitudinal Studies. 1983. As the twig is bent…lasting effects of preschool programs. Hillsdale, NJ: Erlbaum.
26 Pollitt, E.; K. S. German; P. L. Engle. R. Martorell, and J. Rivera. 1993. Early supplementary feeding and cognition. Monographs of the Society for Research in ChildDevelopment. 58(235): 1-99.
27 McMichael, A.J.; P. A. Baghurst; N. R. Wigg; G. Vimpani; E. Robertson; and R. Roberts. 1988. Port Pirie cohort study: environmental exposure to lead and children’s abilities at the age of four years. New England Journal of Medicine. 319: 468-75.
28 Streissguth, A.; H. Barr; P. Sampson; B. Darby; and D. Martin. 1989. IQ at age 4 in relation to maternal alcohol use and smoking during pregnancy. Developmental Psychology. 25: 3-11.
29 Intelligence: Knowns and Unknowns. Board of Scientific Affairs, AmericanPsychological Association. Released August 7, 1995.
30 Rowe, D.; K. Jacobson; and E. Van den Oord. 1999. Genetic and environmental influences on vocabulary IQ: Parental education level as moderator. Child Development. 70: 1151-1162.
31 Flynn, J. R. 1981. The mean IQ of Americans: massive gains 1932 to 1978. Psychological Bulletin. 95: 29-51.
32 Grissmer, D.; S. Kirby, M. Berends; and S. Williamson. 1994. Student achievement and the changing American family. Santa Monica, CA: RAND Corporation.
33 Plomin R. (Ed), J. C. Defries; G. E. McClearn; and P. McGuffin. 2000. Behavioral Genetics. American Psychological Association Publishers.
Science Magazine, Oct 19, 2007
Vol. 318. no. 5849, pp. 399 – 400
Deborah A. Bolnick,1* Duana Fullwiley,2 Troy Duster,3,4 Richard S. Cooper,5 Joan H. Fujimura,6 Jonathan Kahn,7 Jay S. Kaufman,8 Jonathan Marks,9 Ann Morning,3 Alondra Nelson,10 Pilar Ossorio,11 Jenny Reardon,12 Susan M. Reverby,13 Kimberly TallBear14,15 At least two dozen companies now market “genetic ancestry tests” to help consumers reconstruct their family histories and determine the geographic origins of their ancestors. More than 460,000 people have purchased these tests over the past 6 years (1), and public interest is still skyrocketing (1–4). Some scientists support this enterprise because it makes genetics accessible and relevant; others view it with indifference, seeing the tests as merely “recreational.” However, both scientists and consumers should approach genetic ancestry testing with caution because (i) the tests can have a profound impact on individuals and communities, (ii) the assumptions and limitations of these tests make them less informative than many realize, and (iii) commercialization has led to misleading practices that reinforce misconceptions.
The Impact of “Recreational Genetics”
Although genetic ancestry testing is often described as “recreational genetics,” many consumers do not take these tests lightly. Each test costs $100 to $900, and consumers often have deep personal reasons for purchasing these products. Many individuals hope to identify biological relatives, to validate genealogical records, and to fill in gaps in family histories. Others are searching for a connection to specific groups or places in Eurasia and Africa. This search for a “homeland” is particularly poignant for many African-Americans, who hope to recapture a history stolen by slavery. Others seek a more nuanced picture of their genetic backgrounds than the black-and-white dichotomy that dominates U.S. racial thinking.
Genetic ancestry testing also has serious consequences. Test-takers may reshape their personal identities, and they may suffer emotional distress if test results are unexpected or undesired (5). Test-takers may also change how they report their race or ethnicity on governmental forms, college or job applications, and medical questionnaires (6). This could make it more difficult to track the social experiences and effects of race and racism (6). Genetic ancestry testing also affects broader communities: Tests have led African-Americans to visit and financially support specific African communities. Other Americans have taken the tests in hope of obtaining Native American tribal affiliation (and benefits like financial support, housing, education, health care, and affirmation of identity) or to challenge tribal membership decisions (7). Limitations
It is important to understand what these tests can and cannot determine. Most tests fall into two categories. Mitochondrial DNA (mtDNA) tests sequence the hypervariable region of the maternally inherited mitochondrial genome. Y-chromosome tests analyze short tandem repeats and/or single nucleotide polymorphisms (SNPs) in the paternally inherited Y chromosome. In both cases, the test-taker’s haplotype (set of linked alleles) is determined and compared with haplotypes from other sampled individuals. These comparisons can identify related individuals who share a common maternal or paternal ancestor, as well as locations where the test-taker’s haplotype is found today. However, each test examines less than 1% of the test-taker’s DNA and sheds light on only one ancestor each generation (8). A third type of test (DNAPrint’s AncestryByDNA test) attempts to provide a better measure of overall ancestry by using 175 autosomal markers (inherited from both parents) to estimate an individual’s “bio-geographical ancestry.”
Although companies acknowledge that mtDNA and Y-chromosome tests provide no information about most of a test-taker’s ancestors, more important limitations to all three types of genetic ancestry tests are often less obvious. For example, genetic ancestry testing can identify some of the groups and locations around the world where a test-taker’s haplotype or autosomal markers are found, but it is unlikely to identify all of them. Such inferences depend on the samples in a company’s database, and even databases with 10,000 to 20,000 samples may fail to capture the full array of human genetic diversity in a particular population or region.
Another problem is that questionable scientific assumptions are sometimes made when companies report results of a genetic ancestry test. For instance, when an allele or haplotype is most common in one population, companies often assume it to be diagnostic of that population. This can be problematic because high genetic diversity exists within populations and gene flow occurs between populations. Very few alleles are therefore diagnostic of membership in a specific population (9), but companies sometimes fail to mention that an allele could have been inherited from a population in which it is less common. Consequently, many consumers do not realize that the tests are probabilistic and can reach incorrect conclusions.
Consumers often purchase these tests to learn about their race or ethnicity, but there is no clear-cut connection between an individual’s DNA and his or her racial or ethnic affiliation. Worldwide patterns of human genetic diversity are weakly correlated with racial and ethnic categories because both are partially correlated with geography (9). Current understandings of race and ethnicity reflect more than genetic relatedness, though, having been defined in particular sociohistorical contexts (i.e., European and American colonialism). In addition, social relationships and life experiences have been as important as biological ancestry in shaping individual identity and group membership.
Many genetic ancestry tests also claim to tell consumers where their ancestral lineage originated and the social group to which their ancestors belonged. However, present-day patterns of residence are rarely identical to what existed in the past, and social groups have changed over time, in name and composition (10). Databases of present-day samples may therefore provide false leads.
Finally, even though there is little evidence that four biologically discrete groups of humans ever existed (9), the AncestryByDNA test creates the appearance of genetically distinct populations by relying on “ancestry informative markers” (AIMs). AIMs are SNPs or other markers that show relatively large (30 to 50%) frequency differences between population samples. The AncestryByDNAtest examines AIMs selected to differentiate between four “parental” populations (Africans, Europeans, East Asians, and Native Americans). However, these AIMs are not found in all peoples who would be classed together as a given “parental” population. The AIMs that characterize “Africans,” for example, were chosen on the basis of a sample of West Africans. Dark-skinned East Africans might be omitted from the AIMs reference panel of “Africans” because they exhibit different gene variants (11–13). Furthermore, some of the most “informative” AIMs involve loci that have undergone strong selection (14), which makes it unclear whether these markers indicate shared ancestry or parallel selective pressures (such as similar environmental exposures in different geographic regions) or both.
The problems described here are likely responsible for the most paradoxical results of this test. For instance, the AncestryByDNA test suggests that most people from the Middle East, India, and the Mediterranean region of Europe have Native American ancestry (15). Because no archaeological, genetic, or historical evidence supports this suggestion, the test probably considers some markers to be diagnostic of Native American ancestry when, in fact, they are not.
Thus, these tests should not be seen as determining the race or ethnicity of a test-taker. They cannot pinpoint the place of origin or social affiliation of even one ancestor with exact certainty. Although wider sampling and technological advancements may help (16), many of the tests’ problems will remain.
Effects of Commercialization
Although it is important for consumers to understand the limitations of genetic ancestry testing and the complex relation between DNA, race, and identity, these complexities are not always made clear. Web sites of many companies state that race is not genetically determined, but the tests nevertheless promote the popular understanding that race is rooted in one’s DNA (17)–rather than being an artifact of sampling strategies, contrasting geographical extremes, and the imposition of qualitative boundaries on human variation. Because race has such profound social, political, and economic consequences, we should be wary of allowing the concept to be redefined in a way that obscures its historical roots and disconnects it from its cultural and socioeconomic context.
It is unlikely that companies (and the associated scientists) deliberately choose to mislead consumers or misrepresent science. However, market pressures can lead to conflicts of interest, and data may be interpreted differently when financial incentives exist. For scientists, these incentives include paid consultancies, patent rights, licensing agreements, stock options, direct stock grants, corporate board memberships, scientific advisory board memberships, media attention, lecture fees, and/or research support. Because scientific pronouncements carry immense weight in our society, claims must be carefully evaluated when scientists have a financial stake in them. Unfortunately, peer-review is difficult here, because most companies maintain proprietary databases.
As consumers realize that they have been sold a family history that may not be accurate, public attitudes toward genetic research could change. Support for molecular and anthropological genetics might decrease, and historically disadvantaged communities might increase their distrust of the scientific establishment (18). These tests may also come up in medical settings: Many consumers are aware of the well-publicized association between ancestry and disease, and patients may ask doctors to take their ancestry tests into consideration when making medical decisions. Doctors should be cautious when considering such results (19).
We must weigh the risks and benefits of genetic ancestry testing, and as we do so, the scientific community must break its silence and make clear the limitations and potential dangers. Just as the American Society of Human Genetics recently published a series of recommendations regarding direct-to-consumer genetic tests that make health-related claims (20), we encourage ASHG and other professional genetic and anthropological associations to develop policy statements regarding genetic ancestry testing.
References and Notes
- H. Wolinsky, EMBO Rep. 7, 1072 (2006).
- J. Simons, Fortune 155, 39 (2007).
- Thirteen/WNET New York, African American Lives, “Episode 2: The Promise of Freedom,” press release (27 July 2007).
- P. Harris, Observer [London], 15 July 2007, p. 22.
- Motherland, “A Genetic Journey” (Takeaway Media Productions, London, 2003).
- A. Harmon, New York Times, 12 April 2006, p. A1.
- B. Hoerner, Wired 13 (2005).
- A. Yang, Chance 20, 32-39 (2007).
- K. Weiss, M. Fullerton, Evol. Anthropol. 14, 165 (2005).
- C. Rotimi, Dev. World Bioethics 3, 151-158 (2003).
- S. Tishkoff et al., Nature Genet. 39, 31-40 (2006).
- A. Mourant, A. Kopec, K. Domaniewska-Sobczak, The Distribution of the Human Blood Groups and Other Polymorphisms (Oxford Univ. Press, London, 1976).
- M. Hamblin, A. Di Rienzo, Am. J. Hum. Genet. 66, 1669-1679 (2002).
- J. Akey et al., Genome Biol. 12, 1805-1814 (2002).
- M. Shriver, R. Kittles, Nature Rev. Genet. 5, 611 (2004).
- DNAPrint, Frequently asked questions, no. 1, www.ancestrybydna.com/welcome/faq/#q1.
- J. Reardon, Race to the Finish: Identity and Governance in an Age of Genomics (Princeton Univ. Press, Princeton, NJ, 2004).
- In contexts such as gene mapping and genomewide associations, genetic ancestry information can protect against confounding by population stratification or provide evidence of the population origin of specific susceptibility alleles (21). These applications are much narrower than determination of individual ancestry.
- K. Hudson et al., Am. J. Hum. Genet. 81, 635 (2007).
- M. Enoch et al., J. Psychopharmacol. 20, 19 (2006).
1Department of Anthropology, University of Texas, Austin, TX 78712, USA 2Departments of Anthropology and African and African-American Studies, Harvard University, Cambridge, MA3Department of Sociology, New York University, New York, NY