Social Psychology Quarterly
Vol. 73, No. 1, 33–57
Ó American Sociological Association 2010
DOI: 10.1177/0190272510361602
http://spq.sagepub.com

Why Liberals and Atheists Are More Intelligent
SATOSHI KANAZAWA
London School of Economics and Political Science

The origin of values and preferences is an unresolved theoretical question in behavioral andsocial sciences. The Savanna-IQ Interaction Hypothesis, derived from the Savanna Principle
and a theory of the evolution of general intelligence, suggests that more intelligent individuals may be more likely to acquire and espouse evolutionarily novel values and preferences(such as liberalism and atheism and, for men, sexual exclusivity) than less intelligent individuals, but that general intelligence may have no effect on the acquisition and espousal ofevolutionarily familiar values (for children, marriage, family, and friends). The analyses of
the National Longitudinal Study of Adolescent Health (Study 1) and the General Social Surveys (Study 2) show that adolescent and adult intelligence significantly increases adult liberalism, atheism, and men’s (but not women’s) value on sexual exclusivity.
Keywords: origin of values and preferences, evolutionary psychology, the Savanna Principle, the Savanna-IQ Interaction Hypothesis, general intelligenceWhere do individual values and preferences come from? Why do people
want what they want? Some social
scientists and biologists have explored theorigin of values (Emerson 1987; Hechter,
Nadel, and Michod 1993) while economists
have remained mute on the issue. Their traditional answer to the question of individual
values and preferences is: De gustibus non
est disputandum (Stigler and Becker 1977).
There is no accounting for tastes, and one cannot explain individuals’ idiosyncratic values

This research uses data from Add Health, a program
project designed by J. Richard Udry, Peter S. Bearman,
and Kathleen Mullan Harris, and funded by a grant P01HD31921 from the National Institute of Child Healthand Human Development, with cooperative funding
from 17 other agencies. Special acknowledgment is due
Ronald R. Rindfuss and Barbara Entwisle for assistancein the original design. Persons interested in obtaining
data files from Add Health should contact Add Health,
Carolina Population Center, 123 West FranklinStreet,
Chapel Hill, NC 27516-2524; addhealth@unc.edu. I
thank David de Meza, Norman P. Li, Andrew J.
Oswald, Diane J. Reyniers, Pierre L. van den Berghe,and especially Jeremy Freese for their comments on
earlier drafts. Direct all correspondence to Departmentof Management, London School of Economics andPolitical Science, Houghton Street, London WC2A 2AE,
United Kingdom; S.Kanazawa@lse.ac.uk.

and preferences, although Becker (1996) has
since attempted to explain them. A theory of
revealed preferences, which is often used in
microeconomics, only measures individuals’
preferences empirically but does not explain
where they come from or why actors havethem. Despite many attempts and some promising starts (Hechter et al. 1999; Schwartz
1992; Wildavsky 1987), there currently is nosatisfactory general theory of values.
Some argue that evolutionary psychology
can provide such a general theory of values(Ben-Ner and Putterman 2000; Horne 2004;
Kanazawa 2001). Evolutionary psychology is
the study of universal human nature, or sexspecific male human nature and female humannature, and their interaction with the environment. It can therefore in principle explain both
universal preferences (as a function of the universal human nature) and individual preferences (as a function of the interaction between
the universal human nature and individual circumstances and experiences).
In this paper I discuss recent theoreticaldevelopments in evolutionary psychology
and offer one possible explanation ofindividual values and preferences that I
call the Savanna-IQ Interaction Hypothesis.
It explains how the level of general intelligence

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SOCIAL PSYCHOLOGY QUARTERLY

affects the acquisition of certain evolutionarily novel values and preferences. I thentest the Savanna-IQ Interaction Hypothesis
with respect to three evolutionarily novel values (liberalism, atheism, and monogamy) andshow that, consistent with the Hypothesis,
more intelligent individuals are more likely
to espouse liberal political ideology and to
be atheists, and more intelligent men (butnot women) are more likely to value sexualexclusivity. In contrast, and consistent withthe prediction, general intelligence does notaffect the espousal of evolutionarily familiar
values for children, marriage, family, andfriends.
THE SAVANNA PRINCIPLE

Adaptations, physical or psychological,
are designed for and adapted to the conditionsof the environment of evolutionary adaptedness, not necessarily to the current environment (Tooby and Cosmides 1989). This
fundamental principle of evolution holds
equally for psychological adaptations as it
does for physical adaptations. Pioneers of
evolutionary psychology (Crawford 1993;
Symons 1990; Tooby and Cosmides 1990)
all recognized this. Kanazawa (2004a) systematizes these observations into what hecalls the Savanna Principle: The human brain
has difficulty comprehending and dealing
with entities and situations that did not exist
in the ancestral environment. Hagen and
Hammerstein (2005:341-3) refer to the sameobservation as the ‘‘mismatch hypothesis,’’while Burnham and Johnson (2006:130-31)
call it the ‘‘evolutionary legacy hypothesis.’’The Savanna Principle can potentiallyexplain why some otherwise elegant scientifictheories of human behavior, such as the subjective expected utility maximization theory
or game theory, often fail empirically, because
they posit entities and situations that did notexist in the ancestral environment. For example, many players of one-shot Prisoner’s
Dilemma games may make the theoreticallyirrational choice to cooperate with their partner, possibly because the human brain has difficulty comprehending completely anonymous

social exchange and absolutely no possibilityof knowing future interactions (which makes
the game truly one-shot). Neither of these situations existed in the ancestral environment,
but they are crucial for the game-theoreticalprediction of universal defection.
As another illustration of the Savanna Principle, individuals who watch certain types of
TV shows are more satisfied with their friendships, just as they are if they had more friends
or socialized with them more frequently(Kanazawa 2002). This may be because realistic images of other humans, such as television,
movies, videos, and photographs, did not exist
in the ancestral environment, where all realistic images of other humans were other humans.
As a result, the human brain may have implicit
difficulty distinguishing their ‘‘TV friends’’(the characters they repeatedly see on TV
shows) and their real friends. Caughey(1984:31-76) details the ‘‘imaginary social
relations’’ that many Americans have withmedia figures, including TV characters.
EVOLUTION OF GENERAL INTELLIGENCE

General intelligence refers to the ability toreason deductively or inductively, think
abstractly, use analogies, synthesize information, and apply it to new domains (Gottfredson
1997; Neisser et al. 1996). The concept ofgeneral intelligence poses a problem for evolutionary psychology. Evolutionary psychologists contend that the human brain consists ofdomain-specific evolved psychological mechanisms, which evolved to solve specific adaptive problems (problems of survival andreproduction) in specific domains. If the contents of the human brain are domain-specific,
how can evolutionary psychology explain
general intelligence?
In contrast to views expressed by Miller(2000), Cosmides and Tooby (2002), andChiappe and MacDonald (2005), Kanazawa(2004b) proposes that what is now known as
general intelligence may have originally
evolved as a domain-specific adaptation todeal with evolutionarily novel, nonrecurrent
problems. Kanazawa’s (2004b) theory of theevolution of general intelligence represents

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT
some departure from the orthodox in intelligence research. It provides a theoretical definition of general intelligence as well as an
explanation for its evolution, whereas theorthodox intelligence research defines it
only empirically as the highest-order latent
factor—the g factor—that emerges froma factor analysis of a large number of cognitive (‘‘IQ’’) tests. For the orthodox, ‘‘general
intelligence’’ and ‘‘g’’ are completely synonymous, whereas for Kanazawa (2004b) g is anindicator or measure of general intelligence,
not general intelligence itself (Kanazawa
2007:284n).
The human brain consists of a large number of domain-specific evolved psychologicalmechanisms to solve recurrent adaptive problems. In this sense, our ancestors did not
really have to think in order to solve suchrecurrent problems. Evolution has alreadydone all the thinking, so to speak, and equipped the human brain with the appropriate
psychological mechanisms, which engenderpreferences, desires, cognitions, and emotions, and motivate adaptive behavior in thecontext of the ancestral environment.
Even in the extreme continuity and constancy of the ancestral environment, however,there were likely occasional problems thatwere evolutionarily novel and nonrecurrent,
which required our ancestors to think and reason in order to solve. Such problems may
have included, for example:
1. Lightning has struck a tree near thecamp and set it on fire. The fire is
now spreading to the dry underbrush.
What should I do? How could I stop
the spread of the fire? How could I
and my family escape it? (Since
lightning never strikes the sameplace twice, this is guaranteed to bea nonrecurrent problem.)
2. We are in the middle of the severest
drought in a hundred years. Nuts andberries at our normal places of gathering, which are usually plentiful, are
not growing at all, and animals are
scarce as well. We are running out

35

of food because none of our normal
sources of food are working. Whatelse can we eat? What else is safeto eat? How else can we procurefood?
3. A flash flood has caused the river toswell to several times its normal
width, and I am trapped on one sideof it while my entire band is on theother side. It is imperative that I
rejoin them soon. How could I crossthe rapid river? Should I walk acrossit? Or should I construct some sort ofbuoyant vehicle to use to get acrossit? If so, what kind of material should
I use? Wood? Stones?
To the extent that these evolutionarily
novel, nonrecurrent problems happened frequently enough in the ancestral environment(different problem each time) and had serious
enough consequences for survival and reproduction, any genetic mutation that allowed
its carriers to think and reason would havebeen selected for, and what we now call‘‘general intelligence’’ could have evolved asa domain-specific adaptation for the domainof evolutionarily novel, nonrecurrent problems. General intelligence may have become
universally important in modern life
(Gottfredson 1997; Herrnstein and Murray
1994; Jensen 1998) only because our current
environment is almost entirely evolutionarily
novel. The new theory suggests, and empirical
data confirm, that more intelligent individuals
are better than less intelligent individuals at
solving problems only if they are evolutionarily novel, but that more intelligent individuals are not better than less intelligent
individuals at solving evolutionarily familiar
problems, such as those in the domains ofmating, parenting, interpersonal relationships,
and wayfinding (Kanazawa 2004b, 2007).
Three recent studies, employing widely varied
methods, have shown that the average intelligence of a population appears to be a strong
function of the evolutionary novelty of its
environment (Ash and Gallup 2007; Bailey
and Geary 2009; Kanazawa 2008).

36

SOCIAL PSYCHOLOGY QUARTERLYSAVANNA-IQ INTERACTION HYPOTHESISThe logical conjunction of the Savanna
Principle and the theory of the evolution ofgeneral intelligence suggests a qualification of
the Savanna Principle. If general intelligence
evolved to deal with evolutionarily novel
problems, then the human brain’s difficulty incomprehending and dealing with entities andsituations that did not exist in the ancestralenvironment (proposed in the Savanna Principle) should interact with general intelligence,such that the Savanna Principle holds stronger
among less intelligent individuals than among
more intelligent individuals. More intelligent
individuals should be better able to comprehendand deal with evolutionarily novel (but not
evolutionarily familiar) entities and situations
than less intelligent individuals.
There has been accumulating evidence forthis Savanna-IQ Interaction Hypothesis. First,
individuals’ tendency to respond to TV characters as if they were real friends, first discovered by Kanazawa (2002), appears to belimited to those with below-median intelligence (Kanazawa 2006a); individuals withabove-median intelligence do not become
more satisfied with their friendships by watching more television.
Second, net of age, race, sex, education,
marital history, and religion, less intelligent
individuals have more children than more
intelligent individuals, even though they do
not want to do so. This may possibly bebecause they have greater difficulty effectively employing evolutionarily novel meansof modern contraception (Kanazawa 2005).
Another indication that less intelligent individuals may have greater difficulty employing modern contraception effectively is thefact that the correlation between the lifetime
number of sex partners and the number ofchildren is positive among the less intelligent
but negative among the more intelligent. The
more sex partners less intelligent individuals
have, the more children they have; the moresex partners more intelligent individuals
have, the fewer children they have.
Third, more intelligent individuals stayhealthier and live longer than less intelligent

individuals possibly because they are better
able to recognize and deal with evolutionarily
novel threats and dangers to health in modern
society (Deary et al. 2004; Gottfredson and
Deary 2004; Kanazawa 2006b). Consistent
with the Hypothesis, however, general intelligence does not appear to affect health and longevity in sub-Saharan Africa, where many of
the health threats and dangers are more evolutionarily familiar than elsewhere in the world.
Finally, criminologists have long known
that criminals on average have lower intelligence than the general population (Wilson
and Herrnstein 1985; Herrnstein and Murray1994). From the perspective of the Hypothesis,
there are two important points to note (Kanazawa 2009). Much of what we call interpersonal crime today, such as murder, assault,
robbery, and theft, were probably routine
means of intrasexual male competition in theancestral environment. This is how men likely
competed for resources and mating opportunities for much of human evolutionary history;
they beat up and killed each other, and theystole from each other if they could get awaywith it. We may infer this from the fact thatbehavior that would be classified as criminal
if engaged in by humans, like murder, rape,
assault, and theft, is quite common among
other species (Ellis 1998), including other primates such as chimpanzees (de Waal 1998),
bonobos (de Waal 1992), and capuchin monkeys (de Waal, Luttrell, and Canfield 1993).
At the same time, the institutions that control, detect, and punish criminal behavior insociety today—the police, the courts, andthe prisons—are all evolutionarily novel;
there was very little formal third-party
enforcement of norms in the ancestral environment, only second-party enforcement (victims and their kin and allies) or informal
third-party enforcement (ostracism). Thus itmakes sense from the perspective of theSavanna-IQ Interaction Hypothesis that men
with low intelligence may be more likely toresort to evolutionarily familiar means ofcompetition for resources (theft rather thanfull-time employment) and mating opportunities (rape rather than computer dating) andnot to comprehend fully the consequences

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENTof criminal behavior imposed by evolutionarily novel entities of law enforcement.
There thus appears to be some evidence
for the Savanna-IQ Interaction Hypothesis.
Applied to the origin of preferences and values, the Hypothesis suggests that more intelligent individuals may be more likely to acquireand espouse evolutionarily novel preferencesand values than less intelligent individuals,
while general intelligence may make no difference for the acquisition and espousal of evolutionarily familiar values. In particular, theHypothesis leads to predictions about three
evolutionarily novel values of liberalism,
atheism, and, for men, sexual exclusivity,and how general intelligence may affect theiracquisition and espousal.
GENERAL INTELLIGENCE AND
OPENNESS TO EXPERIENCE

Research in personality psychology has
shown that one of the Five-Factor Model personality factors — openness to experience —is significantly positively correlated with intelligence (Ackerman and Heggestad 1997). The
similarity and overlap between intelligenceand openness are apparent from the fact thatsome researchers call this personality factor‘‘intellect’’ rather than ‘‘openness’’ (Goldberg
1992; McRae 1994). While it is widely
accepted by personality psychologists that
intelligence and openness covary across individuals, it is not known why (ChamorroPremuzic and Furnham 2006). The SavannaIQ Interaction Hypothesis can potentiallyexplain why more intelligent individuals are
more open to new experiences and are therefore more prone to seek novelty. It is instructive to note from this perspective that only theactions, ideas, and values facets of openness toexperience are significantly correlated withgeneral intelligence, not the fantasy, esthetics,
and feelings facets (Gilles, Stough, andLoukomitis 2004; Holland et al. 1995).
At the same time, the Hypothesis suggests
a possible need to refine the concept of novelty and to distinguish between evolutionary
novelty (entities and situations that did notexist in the ancestral environment) and37

experiential novelty (entities and situations
that individuals have not personally experienced in their own lifetime). While the FiveFactor Model does not specify the type of novelty that open individuals are more likely toseek, the Savanna-IQ Interaction Hypothesis
suggests that more intelligent individuals are
more likely to seek only evolutionary novelty,
not necessarily experiential novelty.
For example, everybody who is alive in
the United States today has lived their entire
lives in a strictly monogamous society, and,despite recent news events, very few contemporary Americans have any personal experiences with polygyny.1 Therefore monogamy
is experientially familiar for most Americans
whereas polygyny is experientially novel.
The Five-Factor Model may therefore predictthat more intelligent individuals are more
likely to be open to polygyny as an experientially novel idea or action. In contrast, humans
have been mildly polygynous throughout theirevolutionary history (Alexander et al. 1977;
Leutenegger and Kelly 1977), and socially
imposed monogamy is a relatively recent historical phenomenon (Kanazawa and Still
1999). In other words, polygyny is evolutionarily familiar, whereas monogamy is evolutionarily novel. The Savanna-IQ Interaction
Hypothesis would therefore predict that more
intelligent individuals are more likely to beopen to monogamy and less likely to be open
to polygyny. In fact, as the empirical analysis
below shows, more intelligent men are more
likely to value monogamy and sexual exclusivity than less intelligent men.
As another example, for most contemporary Americans, traditional names derived
from the Bible, such as John and Mary, are
1

There is much confusion about terminology for different institutions of marriage, even among social scientists. Monogamy is the marriage of one man to one
woman. Polygyny is the marriage of one man to more than
one woman, while polyandry is the marriage of one
woman to more than one man. Polygamy (although it isoften used synonymously with polygyny in casual conversations) refers to both polygyny and polyandry. Becauseof its ambiguity, the word polygamy should not be used
unless it specifically and simultaneously refers to both
polygyny and polyandry.

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SOCIAL PSYCHOLOGY QUARTERLY

experientially more familiar than untraditional names like Winner and Loser (Levitt
and Dubner 2005). So the Five-Factor Modelmay predict that more intelligent individuals
are more likely to name their children untraditional names like Winner and Loser thanless intelligent individuals. From the perspective of the Hypothesis, however, both John
and Winner are equally evolutionarily novel(because the Bible itself and all the traditional
names derived from it are evolutionarily
novel), so it would not predict that more intelligent individuals are more likely to nametheir children untraditional names. In fact,
there is no evidence at all that more intelligent individuals are more likely to preferuntraditional names for their children (Fryer
and Levitt 2004; Lieberson and Bell 1992).
The Savanna-IQ Interaction Hypothesis
underscores the need to distinguish between
evolutionary novelty and experiential novelty.
It can potentially explain why more intelligent
individuals are more likely to seek evolutionary novelty, but not necessarily experiential
novelty. It further suggests that the establishedcorrelation between openness and intelligence
may be limited to the domain of evolutionary
novelty, not necessarily experiential novelty.
EVOLUTIONARILY NOVEL AND FAMILIAR
PREFERENCES AND VALUES
Liberalism

It is difficult to provide a precise definitionof a whole school of political ideology likeliberalism. Further, what passes as liberalism
varies by place and time. The Liberal Democratic Party in the United Kingdom is middleof-the-road, while the Liberal Democratic
Party in Japan is conservative. The politicalphilosophy which originally emerged as ‘‘liberalism’’ during the Enlightenment is now
called ‘‘classical liberalism’’ or ‘‘libertarianism,’’ and represents the polar opposite ofwhat is now called ‘‘liberalism’’ in the UnitedStates (Murray 1998).
In this paper I will adopt the contemporary
American definition of liberalism. I provisionally define liberalism (as opposed to conservatism) as the genuine concern for thewelfare of genetically unrelated others andthe willingness to contribute larger proportions of private resources for the welfare ofsuch others. In the modern political andeconomic context, this willingness usuallytranslates into paying higher proportions ofindividual incomes in taxes toward the government and its social welfare programs.
Defined as such, liberalism is evolutionarily
novel. Humans (like other species) are designedby evolution to be altruistic toward their genetic
kin (Hamilton 1964), their repeated exchange
partners (Trivers 1971), and members of theirdeme (a group of intermarrying individuals)
or ethnic group (Whitmeyer 1997). They are
not designed to be altruistic toward an indefinite number of complete strangers whom they
are not likely ever to meet or exchange with.
This is largely because our ancestors lived ina small band of 50 to 150 genetically related individuals all their lives, and large cities and nations with thousands and millions of people arethemselves evolutionarily novel.
In order to make reasonable inferences
about what values our ancestors might haveheld during the course of human evolution,
I have relied on two sources. First, I haveconsulted the ten-volume compendium The
Encyclopedia of World Cultures (Levinson
1991-1995), which extensively describes all
human cultures known to anthropology (morethan 1,500) in great detail. Second, I have consulted the following extensive (monographlength) ethnographies of traditional (huntergatherer, pastoral, and horticultural) societies
around the world: Yanomamö (Chagnon
1992); From Mukogodo to Maasai: Ethnicity
and Cultural Change in Kenya (Cronk
2004); Ache Life History: The Ecology and
Demography of a Foraging People (Hill andHurtado 1996); The !Kung San: Men, Women,
and Work in a Foraging Society (Lee 1979);
and Sacha Runa: Ethnicity and Adaptationof Ecuadorian Jungle Quichua (Whitten1976). While contemporary hunter-gatherers
are not exactly the same as our ancestors during the Pleistocene, they are the best analog
that we have available for close examination
and are thus often used for the purpose of
making inferences about our ancestral life.

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT
These ethnographic sources make it clear
that, while sharing of resources, especiallyfood, is quite common and often normatively
prescribed among hunter-gatherer tribes, andwhile trade with neighboring tribes may
have taken place (Ridley 1996), there is noevidence that people in contemporary
hunter-gatherer bands freely share resources
with members of other tribes. Because allmembers of a hunter-gatherer tribe are genetic
kin or at the very least repeated exchange partners (friends and allies for life), sharing resources among them does not qualify as an
expression of liberalism as defined above. It
may therefore be reasonable to infer that,while sharing of food and other resources withgenetic kin may be part of universal humannature, sharing of the same resources withtotal strangers that one has never met or is
not likely ever to meet is not part of evolved
human nature. The Savanna-IQ Interaction
Hypothesis would therefore predict that more
intelligent individuals are more likely toespouse liberal political ideology than lessintelligent individuals.
In an earlier study, Eaves and Eysenck(1974) discover that political attitude (onthe ‘‘radical-conservative’’ scale) has the heritability of .65. More recently, Alford, Funk,and Hibbing (2005) show that roughly 43 percent of the variance in political attitudes on
the conservative-liberal dimension is determined by genes, and parental socialization
has a relatively minor role, accounting for
only 22 percent of the total variance. In
a comprehensive meta-analysis, Jost et al.
(2003) uncover a large number of personality
correlates with conservatism such as deathanxiety and intolerance of ambiguity. Theirstudy, however, does not include general
intelligence as a correlate of political attitude,
except that they show that openness to experience is negatively correlated with conservatism, and we know from studies cited abovethat openness correlates positively with intelligence. Consistent with the prediction
derived from the Hypothesis, Deary, Batty,
and Gale’s (2008a, b) recent studies showthat more intelligent British children are
more likely to become liberal adults.

39

Atheism

While religion is a cultural universal(Brown 1991), recent evolutionary psychological theories (Atran 2002; Boyer 2001;
Guthrie 1993; Haselton and Nettle 2006;
Kirkpatrick 2005) suggest that religiosity(belief in higher powers) may not be an adaptation in itself. It may instead be a byproductof other evolved psychological mechanisms,
variously known as ‘‘animistic bias’’ (Guthrie1993) or ‘‘the agency-detector mechanisms’’(Atran 2002).
When our ancestors faced some ambiguous situation, such as rustling noises nearby
at night or a large fruit falling from a tree
branch and hitting them on the head, they
could attribute it either to impersonal, inanimate, unintentional forces (wind blowing
gently to make the rustling noises among
the bushes and leaves, a mature fruit fallingby its own weight from the branch by theforce of gravity and hitting them on thehead purely by accident) or to personal, animate, intentional forces (a predator sneaking
up on them to attack, an enemy hiding in
the tree branches and throwing fruits at theirhead).
Given that the situation is inherently
ambiguous, our ancestors could have madeone of two errors of inference. They could
have attributed the events to intentional
forces when they are in fact caused by unintentional forces (false-positive or Type I
error) or they could have attributed them tounintentional forces when they were in factcaused by intentional forces (false-negative
or Type II error). The consequences ofType I errors were that our ancestors became
unnecessarily paranoid and looked for predators and enemies where there were none.
The consequences of Type II errors werethat our ancestors were attacked and killedby predators or enemies when they least suspected an attack. The consequences of committing Type II errors are far moredetrimental to survival and reproduction
than the consequences of committing TypeI errors. Evolution should therefore favor
psychological mechanisms which predispose

40

SOCIAL PSYCHOLOGY QUARTERLY

their carriers to commit Type I errors but
avoid Type II errors, and thus overinfer(rather than underinfer) intentions andagency behind potentially harmless phenomena caused by inanimate objects. Evolutionarily speaking, it is good to be paranoid,
because it might save your life (Haselton
and Nettle 2006).
Recent evolutionary psychological theories therefore suggest that evolutionary originof religious beliefs in supernatural forces may
stem from such an innate bias to commit
Type I errors rather than Type II errors. The
human brain may be biased to perceive intentional forces (the hands of God at work)
behind a wide range of natural physical phenomena whose exact causes are unknown. If
these theories are correct, then it means that
religion and religiosity have an evolutionary
origin. It is evolutionarily familiar and natural
to believe in God, and evolutionarily novel
not to be religious.
Once again, in order to make reasonable
inferences about the religious beliefs of ourancestors during the course of human evolution, I have consulted the same primary ethnographic sources on which I relied to makeinferences about their liberalism. Out of
more than 1,500 distinct cultures throughout
the world described in The Encyclopedia ofWorld Cultures, only 19 contain any references to atheism. Not only do all these 19 cultures exist far outside of our ancestral homein sub-Saharan Africa, but all 19 without an
exception are former Communist societies(Abkhazians in Georgia, Ajarians in Georgia,
Albanians, Bulgarians, Chuvash in Russia,
Czechs, Germans in Russia [but not in Germany], Gypsies in Russia, Itelmen in Russia,
Kalmyks in Russia, Karakalpaks in Russia,
Koreans in Russia (but not in Korea), Latvians, Nganasan in Russia, Nivkh in Russia,
Poles, Turkmens, Ukrainian peasants). There
are no non-former-Communist culturesdescribed in The Encyclopedia as containing
any significant segment of atheists. Nor isthere any reference to any individuals who
do not subscribe to the local religion in anyof the monograph-length ethnographies cited
above. It may therefore be reasonable toconclude that atheism may not be part of
the universal human nature, and widespreadpractice of atheism may have been a recent
product of Communism in the twentieth century. The Hypothesis would therefore suggestthat more intelligent individuals are more
likely to be atheist than less intelligent
individuals.
Monogamy

Throughout human evolutionary history,
humans were mildly polygynous. A speciestypical degree of polygyny correlates withthe extent of sexual dimorphism in size; themore sexually dimorphic the species (wheremales are bigger than females), the morepolygynous the species (Alexander et al.
1979; Leutenegger and Kelly 1977). This iseither because males of polygynous species
become larger in order to compete with othermales and monopolize females (Alexander
et al. 1979; Leutenegger and Kelly 1977) or
because females of polygynous species
become smaller in order to mature early andstart mating (Harvey and Bennett 1985;
Kanazawa and Novak 2005; Pickford 1986).
Thus strictly monogamous gibbons are sexually monomorphic (males and females areabout the same size), whereas highly polygynous gorillas are equally highly sexuallydimorphic in size. On this scale, humans are
mildly polygynous, not as polygynous asgorillas, but not strictly monogamous likegibbons.
Consistent with this comparative evidence, an analysis of the Standard CrossCultural Sample (Murdock 1967) showsthat an overwhelming majority of traditional
cultures in the world (83.39 percent) practice
polygyny, with only 16.14 percent practicing
monogamy and 0.47 percent practicing polyandry. Once again, while present-day huntergatherer societies are not the same as ourancestors in every detail, they are our best
analogs available to us to study. The factthat polygyny is widespread in such societies, combined with the comparative data
discussed above, strongly suggests that ourancestors might have practiced polygyny

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT
throughout most of human evolutionary
history.
Under polygyny, one man is married toseveral women, so a woman in a polygynous
marriage still (legitimately) mates only with
one man as a woman in a monogamous marriage does. In contrast, a man in a polygynous
marriage concurrently mates with several
women quite unlike a man in a monogamous
marriage who mates with only one woman.
So throughout human evolutionary history,
men have mated with several women while
women have mated with only one man.2
Sexual exclusivity prescribed under socially
imposed monogamy today is therefore evolutionarily novel for men, but not for women.
The Hypothesis would therefore suggest that
more intelligent men may value sexual exclusivity more than less intelligent men, but
intelligence may not affect women’s likelihood of espousing the value of sexualexclusivity.
Evolutionarily Familiar Values

Unlike liberalism, atheism, and monogamy, values in such evolutionarily familiar
entities as children, marriage (pair-bonding),family, and friends should themselves be evolutionarily familiar. It has always been important to value these entities throughout human
evolutionary history; our ancestors who did
not value these entities are not likely tohave left many descendents. The Hypothesis
would therefore predict that general intelligence may make no difference for the acquisition and espousal of these evolutionarily
familiar values.
2

Of course, polygynous marriage in any society ismathematically limited to a minority of men; most men
in polygynous societies either have only one wife or nowife at all. However, at least some men throughout evolutionary history were polygynous, and we are disproportionately descended from polygynous men with a large
number of wives (because they had more children thanmonogamous or wifeless men). Nor does the human evolutionary history of mild polygyny mean that womenalways remained faithful to their legitimate husband.
There is anatomical evidence to suggest that women havealways been mildly promiscuous (Baker and Bellis 1995;
Gallup et al. 2003).

41

I will test these predictions derived fromthe Savanna-IQ Interaction Hypothesis withregard to the origin of preferences and values
using two separate representative data setsfrom the United States (Add Health and
GSS).

STUDY 1
MethodData. In Study 1, I use the National Longitudinal Study of Adolescent Health (Add
Health). A sample of 80 high schools and 52
middle schools from the United States was
selected with an unequal probability of selection. Incorporating systematic sampling methods and implicit stratification into the Add
Health study design ensures this sample is representative of U.S. schools with respect toregion of country, urbanicity, school size,
school type, and ethnicity. A sample of
20,745 adolescents were personally interviewed in their homes in 1994 through 1995
(Wave I) and again in 1996 (Wave II; n 5
14,738). In 2001 through 2002, 15,197 of theoriginal Wave I respondents, now aged 18 to
28, were interviewed in their homes. My sample consists of Wave III respondents in theirearly adulthood. For further details on thedesign features of Add Health, see http://
www.asanet.org/journals/spq/health.cfm.
Dependent variables. For liberal political
ideology, I use the respondents’ response to
the following question: ‘‘In terms of politics,
do you consider yourself conservative, liberal, or middle-of-the-road?’’ Their responses are coded as follows: 1 5 very
conservative, 2 5 conservative, 3 5 middleof the road, 4 5 liberal, 5 5 very liberal.
For religiosity, I use the respondents’
response to the following question: ‘‘To
what extent are you a religious person?’’
Their responses are coded as follows: 1 5
not religious at all, 2 5 slightly religious,
3 5 moderately religious, 4 5 very
religious. Because both of these dependent variables are measured on an ordinal scale, I use theordinal regression (McCullagh 1980) to estimate these models. For sexual exclusivity, I

42

SOCIAL PSYCHOLOGY QUARTERLY

use the respondent’s response to the following
question: ‘‘Using a scale from 1 to 10, where 1means not important at all and 10 means
extremely important, how important do you
think each of the following elements is fora successful marriage or serious committed
relationship? Being faithful—that is, notcheating on your partner by seeing other people.’’ I use OLS regression to analyze this
response.
Independent variable. Add Health measures respondents’ intelligence with the Peabody Picture Vocabulary Test (PPVT). The
raw scores (0–87) are age-standardized andconverted to the IQ metric, with a mean of
100 and a standard deviation of 15. The
PPVT is properly a measure of verbal intelligence, not general intelligence. However,verbal intelligence is known to be highly correlated with (and thus heavily load on) general intelligence. Miner’s (1957) extensive
review of 36 studies shows that the mediancorrelation between vocabulary and general
intelligence is .83. Wolfle (1980) reportsthat the correlation between a full-scale IQ
test (Army General Classification Test) and
the GSS synonyms measure (which I use laterin Study 2) is .71. As a result, the GSS synonyms measure has been used widely by intelligence researchers to assess trends in general
intelligence (Huang and Hauser 1998), as
well as in research by sociologists who do
not primarily study intelligence (Alwin and
McCammon 1999; Glenn 1999; Wilson andGove 1999).
With respect specifically to PPVT, Zagar
and Mead’s (1983) hierarchical cluster analysisof the Wechsler Intelligence Scale for ChildrenRevised (WISC-R), the Peabody Individual
Achievement Test (PIAT), the Beery Developmental Test of Visual-Motor Integration (VMI)
and the PPVT shows that the PPVT and theVMI, along with some components of the
WISC-R, load on a first-order factor which
they term ‘‘perceptual motor ability,’’ which
in turn loads on a second-order factor
which they term ‘‘general intelligence.’’ As
a result, their conclusion is that the WISC-R,
VMI, and PPVT are all good tests of general
intelligence, whereas the PIAT is a test ofacademic achievement. Stanovich, Cunningham, and Feeman’s (1984) study of first, third,
and fifth graders shows that the correlation
between the PPVT and Raven’s Progressive
Matrices (which is widely regarded as thebest measure of general intelligence) is .22(ns, n 5 56) among the first graders, .52 (p \.05, n 5 18) among the third graders, and .52(p \ .05, n 5 20) among the fifth graders. It
appears that the PPVT becomes a better measure of general intelligence as children getolder.
In order to establish the direction of causality more clearly, I will use the measureof intelligence taken in Wave I (in 1994–
1995 when the respondents were in juniorhigh and high school) to predict their adultvalues in Wave III (in 2001–2002 when the
respondents are in their early adulthood).
Despite the fact that correlation between
measures of intelligence at Waves I and III(taken seven years apart) is not extremely
high (r 5 .5844, p \ .00001, n 5 13,943),
all of my substantive conclusions (and eventhe size of the coefficients) remain the sameif I use Wave III’s measure of intelligence.
Control variables. In addition to adolescentintelligence, I control for the following variables: age (even though there is very little
variance in it given that these are cohort
data); sex (1 if male); race (with three dummies for Asian, black, and Native American,
with white as the reference category, eventhough Add Health respondents can choose
more than one racial category and a small
proportion [4.15%] of them do); education(years of formal schooling); earnings (in dollars); and religion (with four dummies for
Catholic, Jewish, Protestant, and other,with none as the reference category). For
models predicting the value on sexual exclusivity, I also control for the number of times
that the respondent has been married; 81.1
percent of the Wave III respondents havenever been married.
Results

Figure 1a shows a clear monotonic bivariate
relationship between adolescent intelligenceWHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT

43

Figure 1. Mean Adolescent Intelligence by Political Ideology and Religiosity Add Health Data, Wave III(2001–2002). Error bars indicate standard error of the mean.

and adult political ideology. The higher theintelligence of Add Health respondents injunior high and high school, the more liberal
they grow up to be in their early adulthood.
The mean adolescent intelligence of young
adults who identify themselves as ‘‘very liberal’’ is 106.42, while that of those who identify themselves as ‘‘very conservative’’ is94.82. The differences in mean adolescentintelligence by adult political ideology ishighly statistically significant (F(4, 13053) 5
83.6327, p \ .00001).

Figure 1b shows a similarly clear monotonic bivariate relationship between adolescent intelligence and adult religiosity. The
higher the intelligence of Add Healthrespondents in junior high and high school,
the less religious they grow up to be in theirearly adulthood. The absolute difference inmean adolescent intelligence between theextreme categories of religiosity is not as
great as that between the extreme categoriesof political ideology. The mean adolescentintelligence of young adults who identify

44

SOCIAL PSYCHOLOGY QUARTERLY

themselves as ‘‘not at all religious’’ is 103.09,
while that of those who identify themselvesas ‘‘very religious’’ is 97.14. The differenceis still statistically very significant (F(3,14273) 5 78.0381, p \ .00001).
Correlation between adolescent intelligence and the value on sexual exclusivity is
r 5 .0572 (n 5 7,657) among women, andr 5 .0849 (n 5 6,756) among men. The correlation is statistically significantly larger
among men than among women (t 5 2.9774,
n 5 14,413, p \ .01).
Table 1 presents the results from the two
multiple ordinal regression models predicting
adult political ideology and religiosity fromadolescent intelligence and a set of control
variables. Column 1 shows that, net of age,sex, race, education, earnings, and religion,
Add Health respondents who have higher adolescent intelligence are significantly more liberal in early adulthood than those who havelower adolescent intelligence (b 5 .0158,
p \ .0001, standardized coefficient 5 .2380).
A comparison of standardized coefficients(an unstandardized coefficient multiplied by
the standard deviation of the independent
variable to capture the effect of one standard
deviation increase in the independent variable on the dependent variable) shows thatadolescent intelligence has a larger effecton adult political ideology than any othervariable in the model except for religion(Catholicism, Protestantism, and other religion). Despite the fact that past studies showthat women are more liberal than men (Lakeand Breglio 1992; Shapiro and Mahajan
1986; Wirls 1986) and blacks are more
liberal than whites (Kluegel and Smith
1989; Sundquist 1983), the results here showthat adolescent intelligence is twice as strong
an influence on adult political ideology assex (.2380 vs. –.1260) or being black (.2380
vs. .1115).
Table 1, Column 2 shows that, net of thesame control variables, adolescent intelligence has an equally significant effect on
adult religiosity (b 5 –.0212, p \ .0001, standardized coefficient 5 –.1821). Add Healthrespondents who have higher adolescent

Table 1. The Effect of Adolescent Intelligence on
Evolutionarily Novel Values (Liberalism and Atheism)
Add Health Data, Wave III (2001–2002)
Liberal Political
Ideology(1)
Adolescentintelligence
Age

Sex

Race
Asian

Black

Native American

Education

Earnings

Religion
Catholic

JewishProtestant

Other

Threshold
Y51
Y52
Y53
Y54

Religiosity(2).0158****(.0015).2380–.0131(.0119)–.0232–.2524****(.0396)–.1260–.0121****(.0014)–.1821–.0021(.0112)–.0037–.1822****(.0372)–.0910–.0184(.0463)–.0096.1931****(.0437).1115–.1174*(.0556)–.0551.0290**(.0110).0750–.0000**(.0000)–.0640–.1173**(.0444)–.0612.3463****(.0411).2000–.1292*(.0529)–.0606.0542****(.0104).1404–.0000**(.0000)–.0470–.6143****(.0595)–.26551.1356****(.2236).0976–1.0957****(.0688)–.3847–.8246****(.0556)–.40362.3695****(.0618)1.02431.7496****(.2150).1503
2.9244****(.0709)1.02662.8744****(.0598)1.4070–2.7625(.3085)–.3552(.3036)2.3153(.3017)4.8826(.3119)–.2491(.2845)
1.8936(.2857)4.0332(.2867)——(continued)

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT
Table 1. continued
Liberal Political
Ideology(1)x2 goodness of fit
Cox and Snell
pseudo R2
Number of cases

45

Table 2. The Effect of Adolescent Intelligence on
Evolutionarily Novel Values (Sexual Exclusivity forMen) Add Health Data, Wave III (2001–2002)
Religiosity(2)39500.1374.0579

32834.1840****
.2714

9,952

10,673

Note: Main entries are unstandardized regression
coefficients. Numbers in parentheses are standard errors.
Numbers in italics are standardized coefficients (b*sx).
*p \ .05; **p \ .01; ***p \ .001; ****p \ .0001.

intelligence are significantly less religious inearly adulthood than those who have lower
adolescent intelligence. Once again, despite
the fact that past studies show that womenare much more religious than men (Miller
and Hoffmann 1995; Miller and Stark 2002),
adolescent intelligence is twice as strong an
influence on adult religiosity as sex (–.1821vs. –.0910). It is remarkable that adolescentintelligence is a significant and strong determinant of adult religiosity when religion itself
is controlled for (with no religion as the reference category).
Table 2 presents the results for the value on
sexual exclusivity, broken down by sex. The left
column shows that, net of the same control variables as before and the number of marriages,
adolescent intelligence significantly increases
men’s value on sexual exclusivity; the more
intelligent male Add Health respondents are injunior high and high school, the more value
they grow to place on sexual exclusivity. In
sharp contrast, the right column shows that adolescent intelligence has no significant effect on
women’s value on sexual exclusivity; more
intelligent female Add Health respondents are
no more likely to grow up to espouse a value
on sexual exclusivity than their less intelligent
counterparts. The comparison of standardized
coefficients shows that adolescent intelligencehas more than four times as strong an effecton the value for sexual exclusivity for men as
it does for women (.0465 vs. .0110). This is

Sexual Exclusivity

Adolescentintelligence
Age

Race
Asian

Black

Native American

Education

Earnings

Men

Women

.0038**(.0012).0465.0051(.0100)
.0076

.0006
(.0008).0110–.0074(.0068)–.0163.0492(.0380).0227–.1753****(.0355)–.0862.1174**(.0410).0519.0006(.0092).0009–.0000(.0000)–.0061–.0067(.0247)–.0042–.0610**(.0236)–.0409.0140(.0340).0067–.0031(.0061)–.0078.0000(.0000)–.0044

Religion
Catholic.1551***.1468****(.0468)(.0332).0582.0822
Jewish–.1163.0324(.2003)(.1195)–.0081.0037
Protestant.2940****.1337****(.0559)(.0377)
.0860
.0610
Other
.2142****.1367****(.0436)(.0308).0885.0861
Number of marriages.1710***.0245(.0444)(.0262).0557.0134
Constant
8.96409.8878(.2539)(.1636)
R2
.0176
.0066
Number of cases
5,263
5,480
Note: Main entries are unstandardized regression
coefficients. Numbers in parentheses are standard errors.
Numbers in italics are standardized coefficients (betas).
*p \ .05; **p \ .01; ***p \ .001; ****p \ .0001.

46

SOCIAL PSYCHOLOGY QUARTERLY

consistent with the prediction from the Hypothesis. However, the effect of adolescent intelligence on the value on sexual exclusivity is not
as strong as its effects on liberalism or atheism.3
Because it is impossible to have a one standard deviation increase in truly dichotomous
variables like sex or race (as a dummy), one
may suggest that the proper comparison is
between an unstandardized coefficient for the
dichotomous variables (measuring the difference between men and women and thatbetween blacks and whites) and an unstandardized coefficient for adolescent intelligencemultiplied by its standard deviation (to measure the change in the dependent variable associated with one standard deviation increase inadolescent intelligence). These comparisonsshow that the effect of sex on liberal political
ideology is comparable to that of adolescentintelligence (–.2524 vs. .2457), the effect of
being black on liberal political ideology ismuch smaller than that of adolescent intelligence (.1931 vs. .2457), and the effect of sex
on religiosity is comparable to the effect ofadolescent intelligence (–.1822 vs. –.1882).
STUDY 2
MethodData. Because Add Health is cohort dataand includes only respondents in the samegeneration and similar age group (in their earlier twenties), the findings from them may or
may not generalize to all Americans acrossgenerations. In order to ascertain whether
the effect of intelligence can be generalized
to all contemporary Americans in the last 30
years, I now use data from the General Social

3

While both height (Case and Paxson 2008; Jensen
and Sinha 1993) and physical attractiveness (Kanazawa
and Kovar 2004) are correlated with intelligence, entering
them as additional controls does not alter the substantive
findings on the effect of adolescent intelligence. Physicalattractiveness and height have no effect on liberalism;
physical attractiveness significantly (p \ .0001) increases, and height significantly (p \ .001) decreases,
religiosity; physical attractiveness significantly (p \.05) increases men’s (but not women’s) value on sexualexclusivity while height has no effect for either sex.

Surveys (GSS) to examine the effect of intelligence on the espousal of both evolutionarily
novel values (liberalism and atheism) andevolutionarily familiar values (on children,
marriage, family, and friends).
The National Opinion Research Center at
the University of Chicago has administered
the GSS either annually or biennially since1972. Personal interviews are conductedwith a nationally representative sample ofnon-institutionalized adults in the UnitedStates. The sample size is about 1,500 foreach annual survey, and about 3,000 foreach biennial one. The exact questions asked
in the survey vary by the year. Some of thefollowing analyses includes samples frommultiple years (when the relevant questions
are asked multiple times) or a sample fromone year (when the relevant questions are
asked only once).
Dependent variables: Evolutionarily novel
values. For liberal political ideology, I use
the GSS respondents’ response to the following question: ‘‘We hear a lot of talk thesedays about liberals and conservatives. I’mgoing to show you a seven-point scale onwhich the political views that people mighthold are arranged from extremely liberal—point 1 to extremely conservative—point 7.
Where would you place yourself on thisscale?’’ Their response are reverse-coded asfollows: 1 5 extremely conservative, 2 5conservative, 3 5 slightly conservative, 4 5
moderate, 5 5 slightly liberal, 6 5 liberal,
7 5 extremely liberal. The GSS asks this question in every survey year since 1974.
For religiosity, I use two different questions. The first question asks: ‘‘Please lookat this card and tell me which statement
comes closest to expressing what you believe
about God: 1. I don’t believe in God; 2. I
don’t know whether there is a God and I
don’t believe there is any way to find out;
3. I don’t believe in a personal God, but I
do believe in a Higher Power of some kind;
4. I find myself believing in God some of
the time, but not at others; 5. While I havedoubts, I feel that I do believe in God; 6. I
know God really exists and I have no doubts
about it.’’ The GSS asks this question inWHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT
1988, 1991, 1993, 1994, 1998, and 2000. The
second question asks: ‘‘Would you call yourself a strong [respondent’s religion] or a notvery strong [respondent’s religion]?’’ Their
responses are coded as follows: 1 5 no religion, 2 5 somewhat strong, 3 5 not verystrong, 4 5 strong. The GSS asks this question in every survey year since 1974.
Dependent variables: Evolutionarily familiar
values. For evolutionarily familiar values onchildren and marriage, I use the following
question: ‘‘I’m going to read you a list ofsome things that different people value.
Some people say these things are very important to them. Other people say they are not soimportant. Please tell me how important eachthing is to you personally, using the responseon this card. How about having children?
How about being married?’’ Their responses
are coded as follows: 1 5 not at all important,
2 5 not too important, 3 5 somewhat important, 4 5 very important, 5 5 one of the mostimportant. The GSS asks these questions only
in 1993.
For evolutionarily familiar values on family
and friends, I use the following question: ‘‘Onthese cards are various aspects of life. We
would like to know how important each ofthese aspects of life is for you. On each ofthese cards you see on the right hand sidea scale with seven points. The lowest pointwith number 1 indicates that this aspect oflife is unimportant to you. Point 7 at the top indicates that the particular aspect of life is very
important to you. The numbers in between
indicate varying degrees of importance. Pleasetake a look at all the cards first. Then, tell mefor each card its letter and the number you’ve
decided on. One’s own family and children.
Friends and acquaintances.’’ The GSS asks
these questions only in 1982. Because all of
the dependent variables are measured on ordinal scales, I once again use ordinal regression.
Independent variable. The GSS measuresthe verbal intelligence of its respondents byasking them to select a synonym for a wordout of five candidates. Half of the respondents
in each GSS sample answer 10 of these questions, and their total score (the number of correct responses) varies from 0 to 10. I use this47score as a measure of verbal intelligence,
which is known to be highly correlated withgeneral intelligence (Huang and Hauser
1998; Miner 1957; Wolfle 1980).
Control variables. In addition to intelligence, I control for the following variables:age (in years); sex (1 5 male); race (1 5
black); education (years of formal schooling);
earnings (measured in 12 to 23 equidistantordinal categories, here treated as continuous); religion (with four dummies for Catholic, Jewish, Protestant and other, with none as
the reference category); and survey year (onlyfor questions asked in multiple years).
In addition, for models predicting evolutionarily familiar values on marriage, children,
family, and friends, I control for whether
or not the respondent is currently married(1 5 yes), whether or not the respondent has
ever been married (1 5 yes), and the total
number of children.
Results

Table 3 presents the analysis of the GSS
data with respect to the evolutionarily novel
values of liberalism and atheism. Column 1
shows that, net of age, sex, race, education,
earnings, religion, and survey year, GSS
respondents who are more intelligent are
significantly more liberal than those whoare less intelligent (b 5 .0335, p \ .001,
standardized coefficient 5 .0726). Columns
2 and 3 show that, controlling for the same
set of variables, more intelligent individuals
have a significantly weaker belief in God(b 5 –.1048, p \ .0001, standardized coefficient 5 –.2271) and significantly less intense
religiosity (b 5 –.0283, p \ .01, standardized
coefficient 5 –.0613).4 These results are

4
In the model predicting religious intensity (Column3), inclusion of all four religion dummies simultaneously
results in complete separation of data, and the maximum
likelihood estimates thus do not exist. This is because thereference category then is ‘‘no religion,’’ while the lowest
category of the dependent variable is also ‘‘no religion.’’In order to avoid complete separation, I only enter threereligion dummies (Catholic, Jewish, Protestant), thus
leaving the reference category ‘‘no religion and otherreligion.’’

48

SOCIAL PSYCHOLOGY QUARTERLY

Table 3. The Effect of Intelligence on Evolutionarily Novel Values: General Social Survey Data, 1972–2004
Liberal Political Ideology(1)IntelligenceAgeSex (15Male)

Race (15Black)

Education

Earnings

Religion
Catholic

JewishProtestant

Other

Year

Threshold
Y51
Y52
Y53
Y54
Y55
Y56
x2 goodness of fit
Cox and Snell pseudo R2
Number of cases

Belief in God(2)

Religious Intensity(3).0335***(.0091).0726–.0098****(.0013)–.1714–.1994****(.0336)–.0989.5420****(.0480).1867.0142*(.0070).0450–.0148****(.0035)–.0866–.1048****(.0215)–.2271.0072*(.0030).1259–.5084****(.0774)–.2522.6619****(.1360).2280–.0249(.0159)–.0789.0020(.0073).0117–.0283***(.0096)–.0613.0157****(.0013).2745–.2644****(.0352)–.1311.3195****(.0498).1101.0563****(.0073).1783–.0090*(.0036)–.0526–.7686****(.0589)–.3312–.0137(.1224)–.0020–1.0498****(.0548)–.5123–.4659****(.1056)–.0807–.0095****(.0023)–.09232.0418****(.1247).8798.7157**(.2474).1026
2.2861****(.1154)
1.11561.4427****(.2085).2500.0187*(.0090).1817

4.5118****(.0750)1.94424.5643****(.1340).6545
4.6800****(.0718)2.2838———.0028(.0022).0272

34.2737(17.8854)
35.4099(17.8857)
36.4118(17.8862)
36.7681(17.8865)
37.9383(17.8872)——
16874.8644****
.1807
3,200

7.5566(4.4433)
9.2032(4.4435)
11.6322(4.4439)
—
—
—
—
—
—
63737.5261****.3494
13,904–23.7067(4.5650)–21.6938(4.5645)–20.7137(4.5642)–19.0873(4.5636)–18.2036(4.5634)–16.2599(4.5634)
77390.5215.0571
13,034

Note: Main entries are unstandardized regression coefficients. Numbers in parentheses are standard errors. Numbers initalics are standardized coefficients (b*sx).
*p \ .05; **p \ .01; ***p \ .001; ****p \ .0001.

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT
identical to the results from the Add Healthdata in Study 1 reported above.
Table 4 presents the analysis of the GSS
data with respect to the evolutionarily familiar values of children, marriage, family andfriends. Columns 1 through 4 show that intelligence does not have a significant effect on
any of these evolutionarily familiar values(children: b 5 –.0486, ns, standardized coefficient 5 –.1053; marriage: b 5 –.0229, ns,
standardized coefficient 5 –.0469; family:b 5 .0611, ns, standardized coefficient 5.1324; friends: b 5 –.0335, ns, standardized
coefficient 5 –.0726). Now because all fourquestions were asked only in a single year,
the sample size for all models in Table 4 aresmaller than that for models in Table 3. The
smaller sample size is not likely to be the main
reason for the lack of significant effects, however, because other variables included in thesemodels continue to have significant effects.
For example, despite the small sample size,
number of children has a highly significant(p \ .0001) and very large (standardized
coefficient 5 .5829), if very predictable,
positive effect on the value of children. Less
predictably, more educated individuals placea significantly (p \ .05) and moderately(standardized coefficient 5 .2423) greater
value on children, and older individuals placea significantly (p \ .01) and moderately(standardized coefficient 5 –.3532) smaller
value on them.
WHAT DOES IT MEAN TO BE A LIBERAL IN THE
CONTEMPORARY UNITED STATES?

The results presented in Tables 1 and 3
indicate that more intelligent individuals are
more likely to identify themselves as liberal
as opposed to conservative. But what doessuch self-identification mean? Is it consistent
with the operational definition of liberalism
used in this paper? How are self-identified
liberals different from self-identified conservatives? The GSS data can shed some lighton these questions.
Self-identified liberals in the GSS samples
are significantly more likely to agree with thestatements ‘‘It is the responsibility of the49

government to reduce the differences inincome between people with high incomes
and those with low incomes’’ (r 5 .208, p \.00001, n 5 9,306), and with the statement‘‘The government in Washington ought toreduce the income differences between therich and the poor, perhaps by raising the taxes
of wealthy families or by giving income assistance to the poor’’ and less likely to agree withthe statement ‘‘The government should notconcern itself with reducing this income difference between the rich and the poor’’ (r 5.217, p \ .00001, n 5 12,122).
However, even though more intelligent
GSS respondents are more likely to identify
themselves as liberals (Table 3, Column 1),
they are actually less likely to agree with thestatement ‘‘It is the responsibility of the government.’’ (r 5 –.236, p \ .00001, n 55,849) or the statement ‘‘The government inWashington ought to reduce.’’ (r 5 –.167,
p \ .00001, n 5 5,814). Net of the same
demographic controls as in Table 3 (age,sex, race, education, earnings, religion, andsurvey year), intelligence is significantly negatively associated with agreement with thefirst statement (b 5 –.147, p \ .00001) or
the second statement (b 5 –.067, p \.00001) in multiple ordinal regression
equations.
In this paper, however, I provisionallydefine liberalism as the genuine concern for
the welfare of genetically unrelated others
and the willingness to contribute larger proportions of private resources for the welfareof such others. There is some evidence in
the GSS data that self-identified liberals
indeed espouse these values. Reflecting theirgenuine concern for the welfare of geneticallyunrelated others, nonblack liberal GSS
respondents are significantly more likely toagree with the statement ‘‘Blacks have been
discriminated against for so long that the government has a special obligation to help
improve their living standards’’ and lesslikely to agree with the statement ‘‘The government should not be giving special treatment to blacks’’ (r 5 .209, p \ .00001, n 5
19,290). Reflecting their willingness to contribute larger proportions of private resources

50

SOCIAL PSYCHOLOGY QUARTERLY

Table 4. The Effect of Intelligence on Evolutionarily Familiar Values: General Social Survey Data, 1972–2004

IntelligenceAgeSex (15Male)

Race (15Black)

Education

Earnings

Religion
Catholic

JewishProtestant

Other

Currently marriedEver married

Number of children

Threshold
Y51
Y52
Y53
Y54

Children(1)

Marriage(2)

Family(3)

Friends(4)–.0486(.0419)–.1053–.0202**(.0066)–.3532–.4279**(.1491)–.2122–.4836*(.2440)–.1666.0765*(.0316).2423.0026(.0142).0152–.0229(.0417)–.0469.0041(.0066).0717.2724(.1481).1351.0696(.2426).0240.0228(.0313).0722–.0162(.0141)–.0947.0611(.0563).1324–.0175(.0090)–.3060–.5934**(.2259)–.2943.2256(.2492).0777–.0307(.0471)–.0972.0288(.0245).1684–.0335(.0308)–.0726.0187****(.0049).3270–.0222(.1203)–.0110–.4491****(.1328)–.1547–.0468(.0248)–.1482–.0244(.0134)–.1427.7397**(.2583).3187
1.1874*(.5280).1703.7384**(.2341).3603.3176(.4836).0550.5324**(.1901).2646.6497**(.2517).2565.3215****(.0591)
.5829

.4360
(.2578).1879.5651(.5197).0810.7155**(.2349).3492.2922(.4853).0506
2.1984****(.2037)
1.0924–.0574(.2490)–.0227–.0550(.0570)–.09971.1443**(.3488).4931
1.4268(1.0875).2046.7174*(.2928).3501.8132(.8806).1409.1620(.3117).0805
1.3718****(.3435).5416.1302(.0844)
.2361

.3560
(.2201).1534.8562(.4731).1228.4433*(.2036).2163.5311(.5232).0920–.3187*(.1422)–.1584–.2517(.1868)–.0994–.0881*(.0365)–.1597–.8876(.5058).0126(.5012)1.2256(.5037)3.1364(.5143)–.9053(.5066).6433(.5007)
1.9560(.5064)
3.8336(.5203)–3.2897(.7093)–3.0873(.7004)–2.6374(.6861)–2.3133(.6791)–6.2999(.6301)–4.6761(.4444)–3.4213(.4027)–2.1552(.3893)(continued)

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT

51

Table 4. continued
Children
(1)
Y55
Y56
x2 goodness of fit
Cox and Snell pseudo R2
Number of cases————
2733.6806
.1835
683

Marriage
(2)
—
—
—
—
2712.0050
.2719
683

Family(3)

Friends(4)–1.6922(.6712)–.9300(.6674)6586.0304
.0749
1,125

–1.0349(.3849).0546(.3836)6911.0090
.0545
1,126

Note: Main entries are unstandardized regression coefficients. Numbers in parentheses are standard errors. Numbers initalics are standardized coefficients (b*sx).
*p \ .05; **p \ .01; ***p \ .001; ****p \ .0001.

for the welfare of such others, liberals of allraces are significantly more likely to state thatthe amount of federal income tax that they pay
is too low, rather than too high or about right(r 5 .048, p \ .00001, n 5 25,174).
Consistent with the prediction derived
from the Savanna-IQ Interaction Hypothesis,
more intelligent nonblack GSS respondents
are more likely to agree that the government
has a special obligation to help blacks (r 5.060, p \ .00001, n 5 8,610) and more intelligent GSS respondents of all races are more
likely to state that the amount of their federal
income tax is too low (r 5 .039, p \ .0001,
n 5 12,463). Net of the same control variables, intelligence among nonblack respondents is significantly positively associatedwith agreement with the statement that the
government has a special obligation to help
blacks (b 5 .054, p \ .001), and intelligenceis significantly positively associated with thelikelihood that the GSS respondents of allraces state that their federal income tax is
too low (b 5 .052, p \ .001).
It therefore appears that, while they areopposed to government-imposed income
transfers from the rich to the poor, more intelligent individuals are more liberal in the sensethat they exhibit genuine concern for the welfare of genetically unrelated others (nonblacks’ concern for the welfare of blacks),
and that they are willing to contribute larger
proportions of private resources for the welfare of such others (in the forms of higher
federal income tax). It is also instructive tonote that two recent studies, conducted inanother nation (the United Kingdom), using
valid measures of general intelligence, andentirely different indicators of liberalness(nontraditional social attitudes and voting
for the Green Party or the Liberal Democratic
Party), reach the same conclusion that childhood intelligence increases adult liberal attitudes (Deary et al. 2008a, b).
CONCLUSIONThe Savanna-IQ Interaction Hypothesis,
derived from the logical conjunction of theSavanna Principle and a theory of the evolution of general intelligence, suggests that
more intelligent individuals may be more
likely to acquire and espouse evolutionarily
novel values, such as liberalism, atheism,
and, for men, sexual exclusivity, than lessintelligent individuals, while general intelligence may have no effect on the acquisitionand espousal of evolutionarily familiar values.
Data from two large representative samples,the National Longitudinal Study of Adolescent
Health and the General Social Surveys, support the predictions (although some of thestandardized coefficients, while highly statistically significant, are relatively small in size).
Both adolescent and adult intelligence predict
adult espousal of liberalism, atheism, and sexual exclusivity for men (but not for women),while intelligence is not associated with theadult espousal of evolutionarily familiar values
on children, marriage, family, and friends.

52

SOCIAL PSYCHOLOGY QUARTERLY

Given the high heritability of intelligence(Jensen 1998:169-202), and the moderate heritability of political attitudes (Alford et al.
2005; Eaves and Eysenck 1974) and religiosity (Bouchard et al. 1999; Koenig et al. 2005),
one alternative explanation for the effect ofadolescent intelligence on adult political
ideology and religiosity is the genetic transmission of all three traits. Intelligent parents
beget intelligent children; liberal parents
beget liberal children; religious parents beget
religious children.
Such behavior genetic explanations, while
undoubtedly true, cannot explain the origin ofcovariance between general intelligence andcertain values. Why do intelligent parents
tend simultaneously to be liberal and atheist,
to pass on their genetic tendencies toward liberalism and atheism to their intelligent children? Why are there not an equal (orgreater) number of intelligent parents whoare conservative and/or religious, to pass ontheir conservative and religious tendencies
to their intelligent children? Why are there
not many less intelligent parents who are liberal and atheist? Further, behavior genetics
cannot explain why the value on sexualexclusivity (if heritable) is transmitted only
to sons but not to daughters. The SavannaIQ Interaction Hypothesis can offer one possible explanation for the coexistence of general intelligence and certain values.
Another alternative hypothesis is that more
intelligent individuals are more likely notnecessarily to acquire and espouse evolutionarily novel values, as the Hypothesis predicts,
but not to conform to others in the society(Millet and Dewitte 2007). It may be adaptive
for the survival of humans to adopt the rule‘‘The less intelligent you are relative to thosearound you, the more you should mimic theirbeliefs and actions.’’ Because the majority,
under most reasonable conditions, is always
mathematically more likely to be correct
than the average individual (as the Condorcet
Jury Theorem holds), such a decision rule
may save the lives of individuals of lessthan average intelligence.
It is a bit difficult to separate this alternative hypothesis from the prediction of theSavanna-IQ Interaction Hypothesis because
many of the current beliefs in our society,derived as they are from evolved humannature, are evolutionarily familiar. However,
the alternative hypothesis should lead to theprediction that, because contemporary American society is predominantly monogamous,
more intelligent individuals should prefer
polygyny. As the results presented aboveshow, however, this is not the case; more
intelligent men are more likely to prefermonogamy and sexual exclusivity. Further,both in the relatively more conservative capitalist United States and in the relatively more
liberal socialist United Kingdom, more intelligent individuals are more likely to be liberalthan less intelligent individuals (Deary et al.
2008a, b). So it appears that it is not the predominant values of society that affect the values of more or less intelligent individuals, but
their evolutionary novelty.
While it may be reasonable to posit thatliberalism, atheism, and sexual exclusivity
for men may be evolutionarily novel values,
they are far from the only ones. For example,
while the contemporary American definitionof left-wing liberalism may be the polar
opposite of genetic self-interestedness, nepotism, reciprocal altruism, and ethnocentrismof our ancestors, there are other political values that deviate from them, such as communism, monarchism, and libertarianism, toname just a few. Future research would
have to examine whether more intelligent individuals are also more likely to adopt theseevolutionarily novel political ideologies.
What other values are evolutionarily
novel? Another such value is vegetarianism.
Humans are naturally omnivorous, andanyone who eschewed animal protein andate only vegetables in the ancestral environment, in the face of food scarcity and precariousness of its supply, was not likely to havesurvived long and stayed healthy enough tohave become our ancestors. Vegetarianism
would therefore be an evolutionarily novel
value, and the Hypothesis would predict
more intelligent individuals are more likely
to choose to be a vegetarian than less intelligent individuals.

WHY LIBERALS AND ATHEISTS ARE MORE INTELLIGENT
Consistent with this prediction, Gale et al.
(2007) find in their analysis of the 1970 British Cohort Study that, net of sex, social class,and education, childhood intelligence at age
10 significantly increases the probability
that individuals become vegetarian as adults
at age 30. In the Add Health Data, adolescentintelligence (in junior high and high school)
significantly (p \ .05) increases the likelihood of vegetarianism in early adulthood,
net of age, sex, race, education, and earnings.
However, once I control for religion, theeffect of adolescent intelligence becomes only
marginally significant (p \ .07). (Results
available upon request.)
The current work must be extended into
several directions in the future. First, theHypothesis must be tested against other competing theories of the origin of values andpreferences. Second, future empirical work
must consider other evolutionarily novel andfamiliar values besides the ones considered
and tested in this paper. For example, in addition to vegetarianism referred to above, theHypothesis would predict that more intelligent individuals are more likely to espousesuch other evolutionarily novel values as pacifism (for men), feminism, or environmentalism. Third, future empirical work must be
carried out with samples from nations otherthan the United States, such as Gale et al.’s(2007) paper discussed above, which uses
a large British sample to test the effect ofchildhood intelligence on the acquisition ofvegetarianism.
The origin of values and preferences
remains a very important theoretical puzzle
for social and behavioral sciences, and theSavanna-IQ Interaction Hypothesis, at theintersection of evolutionary psychology andintelligence research, provides one deductive
explanation from theoretical first principles
for why individuals have certain values andpreferences. By explaining how general
intelligence may interact with the evolutionary constraints of the human brain, theHypothesis can account for the effect ofintelligence on the acquisition and espousalof evolutionarily novel values. Because the53list of such evolutionarily novel values ispotentially very long, the Hypothesis promises to provide a theoretical explanation for
why intelligent individuals acquire preferences and values in many different domains oflife.
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57

Satoshi Kanazawa is Reader in Management at the London School of Economics and Political Science, and Honorary Research Fellow in the Department of Psychology at University College London
and in the Department of Psychology at Birkbeck College University of London. He has written over
80 articles and chapters in psychology, sociology, political science, economics, anthropology, andbiology. He shares his evolutionary psychological observations in his popular blog, The ScientificFundamentalist, at Psychology Today (http://www.psychologytoday.com/blog/the-scientificfundamentalist). He is the author of Why Beautiful People Have More Daughters (Penguin 2007)
and Escaping Biology: Why Intelligent People Are the Ultimate Losers in Life (tentative title) (Wiley2011).