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Abstract

Evolutionary psychology has provoked controversy, especially when applied to human sex differences. We hypothesize that this is partly due to misunderstandings of evolutionary psychology that are perpetuated by undergraduate sex and gender textbooks. As an initial test of this hypothesis, we develop a catalog of eight types of errors and document their occurrence in 15 widely used sex and gender textbooks. Consistent with our hypothesis, of the 12 textbooks that discussed evolutionary psychology, all contained at least one error, and the median number of errors was five. The most common types of errors were “Straw Man,” “Biological Determinism,” and “Species Selection.” We conclude by suggesting improvements to undergraduate sex and gender textbooks.

Keywords

textbooks evolutionary psychology sex differences sex and gender studies

Introduction

Evolutionary psychology (EP) is a theoretical perspective that applies evolutionary principles to the study of human behavior. Although EP has yielded many theoretical advances and empirical discoveries, it has provoked resistance from some scholars in the social sciences (Confer et al., 2010; Laland and Brown, 2011). This resistance is especially evident when EP is applied to sex and gender differences, but this application is an inevitable extension of powerful theories that were developed by evolutionary biologists (Vandermassen, 2005). Darwin (1871), for example, initially proposed the theory of sexual selection to explain a persistent pattern of sex differences that he and others observed across the animal kingdom. Sexual selection has since been elaborated and shown to be vital for understanding sex differences in many species, including humans (Andersson, 1994; Geary, 2010).

Despite success in explaining cognitive, behavioral, and morphological sex differences in many species, evolutionary theory remains controversial when applied to humans and continues to provoke hostility (Geher and Gambacorta, 2010; Segreståle, 2000; Vandermassen, 2005). Because this controversy has been broadcast to the public in often sensationalist accounts, it might appear more vitriolic than it really is (Kurzban, 2010). The preponderance of complaints and attacks on EP come from scholars outside of the field and are frequently based on misunderstandings of evolution itself or how it is applied to humans (Vandermassen, 2005). Concerned scholars have attempted to correct these misunderstandings and simplistic media portrayals and to build bridges with scholars from other disciplines (e.g., Buss and Schmitt, 2011; Confer et al., 2010). However, many of these corrections and clarifications are published in academic journals that are read by few undergraduates. By contrast, textbooks are a crucial component of an undergraduate's education and are an important conduit of the ideas and data that comprise a paradigm of research (Griggs, Jackson, Christopher, and Marek, 1999). Previous research indicates that textbook accounts of EP are frequently inaccurate (see Previous Textbook Studies section for references), and there apparently has been little effort devoted to improving textbook accuracy.

In this article, we assess the presentation of EP in 15 textbooks on sex and gender. We focus on sex and gender textbooks for three reasons. First, as explained above, evolutionary theory is well suited to contribute to the understanding of sex differences and similarities (Geary, 2010). Second, many sex and gender studies scholars appear skeptical about the merits of EP (Buss and Schmitt, 2011; Vandermassen, 2005). Third, to our knowledge, researchers have not examined the accuracy of sex and gender textbook presentations of EP. Before presenting our coding methodology and results, we briefly investigate potential reasons for mistrust and hostility toward EP among sex and gender studies scholars and review previous presentations of evolutionary psychology in textbooks.

Reasons for Mistrust and Lack of Acceptance

The idea that human nature—including differences between the sexes—is biologically influenced was once relatively standard, indeed, taken for granted by most social scientists (Degler, 1991). In the early 1900's, however, a number of scholars, influenced by the incipient disciplines of cultural anthropology and behaviorism, began to question this assumption. The gradual revelation of the crimes committed by the Nazis alarmed the public and academics alike and further promoted concerns about the social and political implications of biological approaches to human nature (Laland and Brown, 2011). These concerns and skepticism have persisted, to some degree, as protection against what some scholars view as an attempt to justify inequitable social policies and institutions (Lopreato and Crippen, 1999; Lord and Sanderson, 1999). That is, biologically based views of human nature are, within certain academic communities, seen as a form of apologetics for an unjust social system and for myriad other social evils (e.g., sexism, racism, classism). This seems especially true for broadly liberal disciplines that aspire actively to ameliorate social suffering (Geher and Gambacorta, 2010).

However, recent research has shown that, despite popular assumptions, liberalism does not predict a rejection of applying evolutionary theory to humans (Perry and Mace, 2010). Furthermore, from the imperfect data we possess, EPs appear no more likely to adhere to conservative political beliefs than other social scientists (Tybur, Miller, and Gangestad, 2007). Therefore, political ideology, although a probable source of some hostility toward EP, is not a powerful predictor of a scholar's willingness to apply EP to human behavior.

Evidence indicates that, in fact, a misunderstanding of the basic principles of EP is a more powerful predictor of hostility toward it than is political ideology (Perry and Mace, 2010). A student, for example, who is taught that EP ignores the importance of culture might understandably develop a skeptical, perhaps even hostile, attitude toward EP. A similar problem led to hostility toward behaviorism, especially as propounded by B.F. Skinner. Students were taught that Skinner eschewed instincts altogether and that he completely ignored internal processes (Jensen and Burgess, 1997). Instincts and internal processes quite clearly exist, so this led to dismissals of Skinner and accusations that his framework was entirely wrong (in fact, embarrassingly so). These errors were included in textbooks and propagated to the next generation of students, who continued to reject “Skinnerism” (DeBell and Harless, 1992). We suggest that a similar process involving sex and gender textbooks may explain some of the hostility toward EP. Thus, a combination of liberal ideology and broad misunderstanding of the content of EP may combine to lead sex and gender scholars to view EP as a conservative and wrongheaded approach to explaining human sex differences.

As a first step in testing our hypothesis that a cycle of ignorance contributes to the hostility directed toward EP, we coded its presentation in sex and gender textbooks. We predict that presentations of EP will be frequently inaccurate.

It is important to note that sex and gender scholars and sociologists probably hold a more negative view of EP and have more misconceptions than scholars in many areas of psychology (e.g., cognitive scientists, developmentalists, neuroscientists, linguists, etc.) (Geher and Gambacorta, 2010; Lopreato and Crippen, 1999; Perry and Mace, 2010). Many psychologists who do not identify as EPs have fully integrated the Darwinian revolution into their research and possess an acute knowledge of evolution and natural and sexual selection.

Previous Textbook Studies

To our knowledge, five previous studies have examined presentations of EP in undergraduate textbooks. All found that EP presentations were flawed, inaccurate, or, more rarely, hostile. Cornwell, Palmer, Guinther, and Davis (2005) reported that almost 80% of 39 introductory psychology textbooks (years 2000-2004) presented EP inaccurately, and roughly 30% were negative toward EP. Martin and Machaleck (2006) found that 69% of introductory sociology textbooks covered EP in any way, and the ones that did frequently contained errors. Some of the most common errors were claims that EPs adhere to genetic determinism or biological reductionism. Park (2007) studied 10 social psychology textbooks and found that all contained at least one mistaken representation of kin selection, a foundational theory for evolutionary approaches to cooperation. Chrisler and Erchull (2011) examined 16 social psychology textbooks and found that none presented EP uncritically, concluding that, “The most common critique of evolutionary theory seems to be to tell students that cognition and culture can override biological tendencies or that culture restrains or limits biological tendencies” (p. 756). Last, Leahy (2012) found that sociology textbooks tend to reject explicit theories of human nature, including EP, as “biological” and therefore incompatible with the plasticity of human behavior.

Our study extends these previous ones in several ways. First, our study focuses exclusively on sex and gender textbooks. Second, we present a well-defined and explicit catalog of errors pertaining to the presentation of evolutionary theory; previous studies generally did not define the errors they were coding (but see Park, 2007). Third, we provide full documentation for every error we coded so that our procedure and claims are fully transparent.

Materials and Methods

Selecting textbooks

We began identifying social science textbooks that focus on sex and/or gender by contacting Monument Information Resource (MIR), a company that compiles information on undergraduate textbook usage in the United States. MIR provided us with separate databases for a sample of psychology (n = 1,200) and sociology (n = 1,484) courses taught in the U.S. during 2007 with titles similar to “Sex and Gender,” “Women's Studies,” and “Human Sexuality.”1 For each course, information was provided on the institution where the course was taught, the course title, the instructor, the expected enrollment, and any required or recommended books. For both psychology and sociology databases, we sorted the books by title and used online resources, such as reviews and publisher's descriptions, to initially identify introductory textbooks to sex and gender that were broad in scope, including discussions of both social and biological factors that influence gender-differentiated behavior. We excluded textbooks published prior to 2005, edited volumes, encyclopedias, readers or article compilations, specialized academic books (e.g., on sexual violence, human sexuality, gender and aging, gender and religiosity, gender and math, gender and labor markets, gender and group processes), and non-academic books (e.g., those marketed toward parents or lay audiences). These categories of books were excluded to 1) keep our sample manageable and 2) because undergraduate textbooks form the core of most undergraduate classes (Griggs et al., 1999) and, therefore, are most informative in gauging the mainstream view of the discipline. In cases where it was unclear if a book was appropriate, we obtained it and collectively made a judgment.

We obtained the 15 textbooks (six sociology; nine psychology) that were used in more than one course in the MIR database and met our criteria for inclusion. At least one of these six sociology textbooks was used in 712 of 1,484 sociology courses (48%); the most widely used book was used in 326 courses (22%), and the least widely was used in 15 courses (1%). At least one of these nine psychology textbooks was used in 552 of 1,200 psychology courses (46%); the most widely used book was used in 124 courses (10%), and the least widely was used in 21 courses (2%). See references for the number of courses that used each textbook.

Identifying relevant pages

To find the pages in the textbooks that covered EP, we searched the index for three key phrases (evolutionary theory, evolutionary psychology, and sociobiology). We summed the pages and checked each page thoroughly for the errors listed in our catalog.

Developing the error catalog

We identified types of errors by reading previous textbook analyses, evolutionary psychology textbooks, and introductory sex and gender textbooks. We identified eight major types of errors, each of which is discussed in the catalog below. We note our error catalog, like any other, is somewhat arbitrary. However, the errors listed in our catalog were selected because EPs themselves have addressed them, sometimes repeatedly. We also note that the Straw Man category is something of a catch all category which includes Biological Determinism, Naturalistic Fallacy, Political Agenda, and the Intentionalistic Fallacy. That said, there were several egregious misrepresentations that simply did not fit in these categories and we felt these deserved to be made explicit and rebutted. Therefore, our Straw Man (not otherwise specified) category includes straw man arguments that are not captured by the other error types. The Appendix also corrects a few errors that were not formally coded for analysis. We encourage other scholars to code textbooks using different or expanded error catalogs.

Identifying errors

The first author initially coded errors by occurrence and type. He then directed the second author to each passage containing an apparent error, and the second author independently classified it according to error type. They agreed in 87% of cases (Cohen's κ = .85), and disagreements were resolved by discussion.

The error catalog

Below is a list of the eight types of errors we coded with an explanation, rebuttal, and textbook example of each. E#) denotes the type of error and R#) provides a rebuttal of the error. Note that four of these errors—Biological Determinism, Naturalistic Fallacy, Political Agenda, and Intentionalistic Fallacy—are ones that EPs are accused of making, whereas the others are made in the explication of evolutionary theory and its application to humans.

E1) Lack of Evidence/Lack of Falsifiability. The assertion that many or all claims by EPs (1) lack substantive confirmatory evidence and/or (2) are unfalsifiable.

R1) (1) Evidence supports many claims made by EPs. Buss, Haselton, Shackelford, Bleske, and Wakefield (1998), Table 1) summarized 30 empirical discoveries about human nature generated by explicit evolutionary theorizing, including mother-fetus conflict and landscape preference. More recently, Buss and Schmitt (2011, Table 1) summarized 17 robust empirical findings regarding sex differences in desire for sexual variety. Many more empirical findings are reviewed in introductory evolutionary psychology textbooks (e.g., Badcock, 2000; Barrett, Dunbar, and Lycett, 2002; Buss, 2008; Cartwrigtht, 2000; Gaulin and McBurney, 2004; Workman and Reader, 2004). (2) Most hypotheses proposed by EPs are falsifiable. Buss's introductory textbook (1999) presented 11 methods and data sources for testing evolutionary hypotheses (p. 54) and concluded that at least two of the methods must support a hypothesis for it to have a “firm empirical foundation” (p. 65). Ketelaar and Ellis (2000) devoted a full article to falsifiability and demonstrated that the charge that EP claims are generally unfalsifiable is unwarranted. Last, Schmitt and Pilcher (2004) laid out a rigorous program for testing evolutionary based hypotheses, and this emphasized the importance of generating and testing empirical predictions.

Table 1.

Summary of textbook errors

Textbook (Year)	Discipline	# of Pages	Errors Made	Totals
Textbook (Year)	Discipline	# of Pages	Errors Made	Types of Errors	Overall Errors
Rider (2005)	Psych	9	E2, E4, E6	3	3
Johnson (2005)	Soc	1	E3	1	1
Lips (2006)	Psych	5	E2, E5, E6	3	3
Smith (2007)	Psych	2	E6	1	1
Lips (2008)	Psych	11	E1, E2, E5 (2), E6 (3), E7, E8 (2)	6	10
Caplan & Caplan (2009)	Psych	9	E1, E3 (3), E5 (3), E6 (2)	4	9
Connell (2009)	Soc	4	E1, E2 (2), E4 (2), E6, E8	5	7
Brannon (2011)	Psych	7	E2 (2), E4	2	3
Lindsey (2011)	Soc	6	E1 (2), E2 (2), E4, E5 (2), E6, E7	6	9
Anderson (2011)	Soc	0		0	0
Helgeson (2012)	Psych	7	E2, E5, E7	3	3
Crawford (2012)	Psych	0		0	0
Renzetti, Curran, & Maier (2012)	Soc	0		0	0
Hyde & Else-Quest (2013)	Psych	7	E2 (2), E4 (2), E5, E6 (2), E8	5	8
Kimmel (2013)	Soc	15	E1 (2), E2 (2), E3, E6 (5), E7, E8	6	12

Note. For complete textbook citation information see references. # of Pages refers to the pages the textbook devoted to covering EP. Error number corresponds to the coding rubric and the number in the parentheses refers to the number of times the particular error occurred in the textbook. So E5 (2) means that error number five (species selection) occurred two times in the textbook.

Textbook Example: “Sociobiology has some success in applying evolutionary theory to animal behavior, but because it is virtually impossible to test the natural selection principles on which it is based, empirical support for evolutionary links to human behavior is weak.” (Lindsey, 2011, p. 25).

E2) Biological Determinism/Dichotomy between Nature & Nurture. (1) The assertion that EPs contend that biology determines or can explain all human behavior. (2) The assertion that some phenomena are entirely cultural whereas others are entirely biological.

R2) (1) EPs do not contend that human nature is “hardwired” by genes or determined exclusively by “biology.” In fact, introductory evolutionary psychology textbooks warn about deterministic views of human nature (e.g., Buss, 2008; Gaulin and McBurney, 2004). For example, Rossano (2003) states, “Evolutionary psychologists firmly reject both genetic determinism and environmental determinism and, instead, contend that both genes and environment must be considered in understanding the human mind” (p. 28). (2) EPs believe that understanding human nature requires an interactionist framework; i.e., incorporating both biology and culture. As Tooby and Cosmides (1992) point out:

Evolution shapes the relationship between the genes and the environment such that they both participate in a coordinated way in the construction and calibration of adaptations. Thus, evolutionarily patterned structure is coming in from the environment, just as much as it is coming out from the genes. (p. 86)

In short, nature and nurture are inseparable in the EP account.

Textbook Example: “What's more, if these [biological] explanations are true, no amount of political initiative, no amount of social spending, no great policy upheavals will change the relationships between women and men” (Kimmel, 2013, p. 22).

E3) Naturalistic Fallacy. The assertion that EPs contend that what exists is either ipso facto good or morally desirable simply because it exists.

R3) The accusation that EPs are guilty of the naturalistic fallacy is belied by numerous writings from early sociobiologists (e.g., Alexander, 1979; Symons, 1979) and more recently from evolutionary psychologists. In The Selfish Gene, Richard Dawkins (1976) writes, “I am not advocating a morality based on evolution. I am saying how things have evolved. I am not saying how we humans morally ought to behave” (pp. 2-3). Many introductory textbooks on evolutionary psychology contain explicit warnings about committing the naturalistic fallacy (e.g., Bridgeman, 2003; Buss, 1999; Cartwright, 2000; Palmer and Palmer, 2002; Rossano, 2003).

Textbook Example: “Biological arguments reassure us that what is is what should be, that the social is natural. Finally, such reassurances tell us that these existing inequalities are not our fault, that no one is to blame, really” (Kimmel, 2013, p. 22).

E4) Political/Ideological Agenda/Consequentialist Fallacy. (1) The assertion that EPs have a conservative, rightwing political agenda and that this agenda significantly influences their research. (2) The assertion that evolutionary accounts are morally dubious and possibly dangerous if widely disseminated.

R4) (1) To the extent that we have empirical data on the political views of EPs, this assertion appears to be false. Most of the early sociobiologists were liberals or social democrats (including E.O. Wilson and Richard Dawkins), while Robert Trivers, who developed the theory of parental investment, was a political radical who coauthored a paper with Huey Newton (Segreståle, 2000; Trivers, 2002). A recent study of EPs found that their political views match those of social scientists in general—0 of 31 EPs identified with the Republican Party (Tybur et al., 2007). Even if it were true that EPs have more conservative views than other social scientists, it would not automatically follow that they are more likely than others to use their scholarship to advance a conservative agenda. We know of no data addressing this possibility, and the textbooks making this assertion do not provide any evidence for it. (2) Unfortunately, almost any view of human nature can be used to justify self-serving behavior that harms other people, ranging from the extremes of Nazism on the right to communism on the left (Pinker, 2002). The communists, for example, perpetrated numerous ghastly crimes, which were justified by a singular commitment to human flexibility, environmental determinism, and equality (Pipes, 2001). However, the factual content of a theory or proposition is not determined by the perceived good or ill it may do to society.

Textbook Example: “Another concern is the claim that gender differences have evolved over time, which implies that gender differences are inevitable and unchangeable. Biology then becomes an excuse for accepting differences and not advocating for social change” (Rider, 2005, p. 117).

E5) Species Selection. The assertion that evolution via natural and sexual selection operates to ensure species survival or that the survival of the species is the “goal” of evolution.

R5) Charles Darwin (1859/1958; 1871) argued that natural and sexual selection targeted the individual, not the species. In the 1960s, evolutionary biologists revolutionized the field by formalizing the insight that it was not the individual but the gene that was the fundamental unit of selection (Dawkins, 1976; Hamilton, 1964a,b). Although there is debate about the importance of differing units or levels of selection (e.g., group, individual, gene; Wilson and Wilson, 2007), biologists are nearly unanimous that species level selection does not occur:

In the early post-Darwinian period when thinking about selection was rather confused, it was often said that such and such a character had evolved because it was “good for the species.” This is quite misleading. The selected character had originated because it benefited certain individuals of a species and had gradually spread to all others. The species as an entity does not answer to selection. (Mayr, 1997, p. 2092)

Textbook Example: “Evolutionary theory argues that in any species, including humans, certain characteristics persist across generations—passed along genetically—because they help the species survive” (Lips, 2006, p. 132).

E6) Straw Man Argument (Not Otherwise Specified). A misrepresentation of the opponent's position which creates the illusion that the argument in question has been refuted when, in fact, the actual position of the opponent has not been addressed.

R6) Straw Man arguments must be examined case by case but often involve oversimplifying the arguments of EPs to make them appear careless or reductionist. For example, many critics of EP assert that the theory posits that all men are promiscuous when, to our knowledge, this is not a serious position of EPs.

Textbook Example: Because each Straw Man argument is somewhat unique, aside from those that fall into specified errors we have already cataloged, each requires its own explanation (see Appendix for detailed comments on each coded Straw Man error).

E7) Intentionalistic Fallacy. The assertion that EPs contend that humans intentionally attempt to enhance their inclusive fitness and are explicitly aware of such intentions. For example, the claim that using contraception and engaging in sex for the sake of pleasure rather than reproduction refutes evolutionary arguments regarding natural and sexual selection.

R7) EPs do not believe that humans are consciously aware of the “evolutionary logic” of their behavior. E.O. Wilson, the founder of sociobiology, made the point that the brain “has been programmed to perform as if it knows [emphasis added]” the underlying evolutionary logic of its affective biases (Wilson, 1975, p. 4). Similarly, John Tooby and Leda Cosmides (1992), two of the founders of evolutionary psychology, state “… the biological concept of functionality differs from the folk notion of functionality as goal-seeking behavior. Although some of our evolved psychological mechanisms probably operate through goal-seeking, surely none of them has fitness maximization as a mentally represented goal” (p. 54). Even in cases where humans explicitly represent goals (e.g., I need to protect my child; I would like to have sex), EPs do not posit that they are aware of the evolutionary logic guiding the specific goal in question (see for example, Buss, 1999; Geary, 2005).

Textbook Example: The sociobiological view of sex differences assumes that sexual intercourse will lead – or is intended to lead – to reproduction. Today, I doubt that the majority of men are thinking about establishing paternity and the majority of women are thinking about their partners' ability to support a child when deciding whether or not to engage in sex. (Helgeson, 2012, p. 114)

E8) Mechanical Demonstration. The assertion that if a scholar lacks knowledge of the specific proximate mechanism(s) contributing to a behavior, then that scholar is unable to legitimately make any claims about the evolutionary function of the behavior. For example, the claim that sex differences in cognition cannot have an evolutionary basis because the precise genes, neurotransmitters, and evolutionary pressures giving rise to them are not perfectly understood.

R8) It is, of course, desirable to have perfect knowledge of all of the physiological, genetic, and historical components of a hypothesized adaptation, but this is not necessary to make informed hypotheses about human adaptations. George Williams (1966) developed rigorous criteria for evaluating adaptations (reliability, efficiency, and economy) and these criteria can be used for evaluating evident design features of humans (e.g., the eye, opposable thumbs, fever) without knowing the precise physiological basis of the adaptation in question (see also Buss, 1999; Tooby and Cosmides, 1992). We also note that scholars using non-evolutionary perspectives routinely and fruitfully advance hypotheses about the causes of behavior without providing a comprehensive account of all mechanisms involved in the causal pathway.

Textbook Example: Evolutionary psychologists fail to specify the biological mechanisms from evolution to behavior. Their basic arguments are that evolution occurred over millions of years and, voila, we have a certain pattern of gender differences in the 21^st century. But evolution can act only through genes, and genes influence behavior because they direct the synthesis of certain proteins and not others, leading to differing levels of biochemicals such as neurotransmitters or hormones. This is the era of the Human Genome Project, in which specific genes that create specific medical conditions and behaviors are being identified. Evolutionary psychology has failed to incorporate this work, and fails to specify which genes and biochemicals are responsible for the patterns of gender differences that they claim have evolved. (Hyde and Else-Quest, 2013, p. 35)

Results

Three textbooks (Anderson, 2011; Crawford, 2012; Renzetti, Curran, and Maier, 2012) were not coded because they did not discuss the theoretical framework of EP. Of the 12 remaining textbooks, all contained at least one error (see Table 1 and Fig. 1; see Appendix for complete documentation of every coded error). The mean number of errors per book was 5.75 (SD = 3.81) and the median was 5; this statistic allows that a book may commit an error type more than once. Across books, the mean number of error types was 3.75 (SD = 1.86) and the median was 3.5. Not surprisingly, there was a strong correlation between the number of pages devoted to discussing EP and total errors, r = .73.

Figure 1.

Frequency of cataloged errors

The Straw Man error was the most frequent, occurring 17 times in nine textbooks. Because this category of error is the most open-ended, the result is not surprising. The Biological Determinism/Dichotomy between Nature and Nurture error was the second most frequent (14 times in nine textbooks). The Naturalistic Fallacy and Intentionalistic Fallacy errors were the least frequent, occurring four times in three textbooks and four times in four textbooks, respectively. Psychology undergraduate textbooks devoted more pages to EP (M = 5.67, SD = 3) than did sociology textbooks (M = 3.67, SD = 4.59); Sociology textbooks contained more types and more overall errors than did psychology textbooks (see Table 2). We note that the sample size was extremely small so these results should be treated with due caution.

Table 2.

Errors by type of textbook

Type of Textbook	Sample size	Types of errors	Overall errors
Sociology	4	4.5 (2.38)	7.25 (4.65)
Psychology	8	3.38 (1.60)	5 (3.42)

Note. Mean (Standard Deviation)

Discussion

Our study improves upon previous studies by furnishing a well-defined catalog of errors in the presentation of EP and demonstrating that these errors occur frequently in undergraduate sex and gender textbooks. EPs have frequently addressed these errors (Buss, 1999; Confer et al., 2011; Pinker, 2002), but our results demonstrate that, despite these efforts, errors persist.

Although these results are discouraging, they are also encouraging because the factual errors can be corrected and future textbook writers, equipped with a more accurate understanding of evolutionary theory, can produce balanced (but critical) textbooks. EP should be exposed to rigorous criticism and debate; however, that cannot happen if researchers are not well-informed. There are well-informed criticisms of EP's analysis of sex differences, and these can lead to a more comprehensive and flexible theory. For example, Wood and Eagly (2012) have published widely cited criticisms of a biologically-based analysis of the origins of human sex differences. Scholars debate their conclusions, but they can serve as catalysts for future research and clarification of hypotheses (see also Eagly and Wood, 1999; Wood and Eagly, 2002).

A possible concern with the current study is the accuracy of our error catalog. Perhaps, for example, EPs do espouse a form of biological determinism (E2), a common attribution of the textbooks (see Results), despite explicitly arguing that evolutionary theory does not entail such determinism. To some degree, this will depend upon perspective. A researcher who believes that biology plays no role in causing sex and gender differences will view any suggestion otherwise as redolent of biological determinism. What is important, however, are not the specifics of this debate, but rather whether EP is accurately represented in textbooks. The passages in sex and gender textbooks that we coded as errors are contradicted by quotes from EP textbooks, which consistently urge researchers to avoid making the four fallacies attributed to evolutionary psychologists (see EP textbooks in references). Furthermore, these passages are contradicted by numerous peer-reviewed articles (see EP textbooks for references).

The evidence for all errors is provided in the Appendix, and researchers can evaluate these themselves. Some might argue that specific EPs do make the errors imputed to them by the textbooks we coded. However, our contention is that mainstream EP as a field does not commit these errors and should not be judged nor characterized by the writings or assertions of one or two unorthodox scholars. Moreover, in making these claims (“EPs generally espouse Biological Determinism”), the textbooks invariably failed to provide a single case of an EP making the error.

We anticipate a few more concerns, some of which represent limitations of the present research and some of which underscore the need for further research. First, we did not apply our catalog of errors to textbooks that were not focused on sex and gender. This should be done because general introductory textbooks reach a wider audience than sex and gender textbooks.

Second, sex and gender researchers from a more social constructionist perspective may argue that EP textbooks and articles similarly mischaracterize their theories and arguments. If true, we welcome careful documentation of this problem, because this can lead to increased understanding. Nevertheless, this does not mitigate or excuse the shoddy treatment of EP documented here.

Last, we simply demonstrated that textbooks frequently make errors; we did not establish that such errors are perpetuated or have an impact on students. It is, however, reasonable to posit that students are exposed to these errors (from reading textbooks, listening to lectures, or both) and that such exposure influences student attitudes about EP, as we hypothesized. More research is necessary to demonstrate causal links between textbook errors and student knowledge and attitudes. A clear prediction from the current research is that students will be more hostile toward EP after taking sex and gender classes and that the hostility of the used textbook will moderate this effect.

On a practical level, we suggest several recommendations to improve the quality of textbooks. First, sex and gender textbook writers could communicate with EPs and send them preliminary versions of their chapters. Second, EPs could write their own textbooks. This would certainly increase the accuracy of the presentation of EP. However, it may create its own problems and may provoke suspicion in an unsympathetic audience. Perhaps the best solution would be to encourage more collaboration between EPs and researchers who operate from different theoretical perspectives. This would allow both perspectives full and honest expression and would allay the concerns of skeptical researchers who might anticipate ideological distortions from authors who belonged to one theoretical camp or another.

Footnotes

Acknowledgements

The authors are grateful to MIR and Rob Staats for providing textbook data and David Geary and two anonymous reviewers for feedback on earlier versions of the manuscript.

1

MIR used “Human Sexuality” as a key research term when providing data about classes on sex and gender and textbook usage. However, we were interested in introductory textbooks on sex and gender and thus excluded specialized textbooks on human sexuality. Some courses with course titles similar to Human Sexuality served as introductory courses to sex and gender in general whereas others were more specialized.

Appendix: Documentation of all Coded Errors

Note: E# = Error number from coding rubric; R# = See coding rubric rebuttal for explanation of error.

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Misrepresentations of Evolutionary Psychology in Sex and Gender Textbooks

Abstract

Keywords

Introduction

Reasons for Mistrust and Lack of Acceptance

Previous Textbook Studies

Materials and Methods

Selecting textbooks

Identifying relevant pages

Developing the error catalog

Identifying errors

The error catalog

Results

Discussion

Footnotes

Acknowledgements

1

Appendix: Documentation of all Coded Errors

References