Copyright
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First Edition: January 2020
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Library of Congress Control Number: 2019952691
ISBNs: 978-1-5387-4401-7 (hardcover), 978-1-5387-4400-0 (ebook)
E3-20191205-JV-NF-ORI
Contents
Cover
Title Page
Copyright
Dedication
Epigraph
A Note on Presentation
Introduction
Part I
“Gender Is a Social Construct”
1. A Framework for Thinking About Sex Differences
2. Sex Differences in Personality
3. Sex Differences in Neurocognitive Functioning
4. Sex Differences in Educational and Vocational Choices
5. Sex Differences in the Brain
Part II
“Race Is a Social Construct”
6. A Framework for Thinking About Race Differences
7. Genetic Distinctiveness Among Ancestral Populations
8. Evolution Since Humans Left Africa
9. The Landscape of Ancestral Population Differences
Part III
“Class Is a Function of Privilege”
10. A Framework for Thinking About Heritability and Class
11. The Ubiquity of Heritability and the Small Role of the Shared Environment
12. Abilities, Personality, and Success
13. Constraints and Potentials
Part IV
Looking Ahead
14. The Shape of the Revolution
15. Reflections and Speculations
Acknowledgments
Discover More
About the Author
Appendix 1: Statistics for People Who Are Sure They Can’t Learn Statistics
Appendix 2: Sexual Dimorphism in Humans
Appendix 3: Sex Differences in Brain Volumes and Variance
Notes
References
To Harlan Crow
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I remember once being entreated not to read a certain newspaper lest it might change my opinion upon free-trade. “Lest I might be entrapped by its fallacies and misstatements,” was the form of expression. “You are not,” my friend said, “a special student of political economy. You might, therefore, easily be deceived by fallacious arguments upon the subject. You might, then, if you read this paper, be led to believe in protection. But you admit that free-trade is the true doctrine; and you do not wish to believe what is not true.”
—Charles Sanders Peirce
“The Fixation of Belief,” 1877
A Note on Presentation
Human Diversity is grounded in highly technical literatures involving genetics, neuroscience, and statistics. It must satisfy two audiences with completely different priorities: my intended reader and the experts.
I’ve always thought of my intended reader as someone who enjoys reading the science section of the New York Times—curious about scientific matters, but someone who wants the gist of the science, not the minutiae. I need to keep the narrative moving. But I am conveying material that often has daunting technical complexities. Readers also need to be able to compare my claims with the details of the underlying evidence. I use my three favorite devices: Boxed text introduces related issues that are interesting but not essential. Appendixes provide full-scale discussions of important ancillary issues. Endnotes expand on points in the main text. But Human Diversity uses these devices, especially the endnotes, even more extensively than I have in the past. Some of the endnotes are full-scale essays, complete with tables. Brackets around a callout number for an endnote indicate that it contains at least a substantial paragraph of additional exposition.
For this complicated book, I have had to add a fourth device. In the past, I have usually been able to avoid technical jargon in the main text. Human Diversity doesn’t give me that option. Too much material cannot be discussed without using technical terms that will be new to many readers. I therefore insert periodic interludes in the text to explain them.
I have also tried to make the book more accessible by my treatment of charts and tables. Sometimes the information in a figure or table is complicated enough to warrant giving it a title and traditional formatting. But often a simple graph of a trendline or a few summary statistics don’t need the folderol. They can be integrated into the text so that you can absorb the simple point that’s being made and move on.
Introduction
If you have picked up Human Diversity looking for bombshells, you’ll be disappointed. I’m discussing some of the most incendiary topics in academia, but the subtext of the chapters to come is that everyone should calm down. The differences among human groups are interesting, not scary or earthshaking. If that sounds boring, this isn’t the book for you.
If, on the other hand, you have reached this page convinced that gender, race, and class are all social constructs and that any claims to the contrary are pseudoscience, you won’t get past the first few pages before you can’t stand it anymore. This book isn’t for you either.
Now that we’re alone, let me tell you what Human Diversity is about and why I wrote it.
The sciences form a hierarchy. “Physics rests on mathematics, chemistry on physics, biology on chemistry, and, in principle, the social sciences on biology,” wrote evolutionary biologist Robert Trivers.1 If so, this century should be an exhilarating time to be a social scientist. Until now, we social scientists—for I am a member of that tribe—have been second-class citizens of the scientific world, limited to data and methods that cast doubt on our claim to be truly part of the scientific project. Now, new possibilities are opening up.
Biology is not going to put us out of business. The new knowledge that geneticists and neuroscientists are providing, conjoined with the kinds of analyses we do best, will enable us to take giant strides in understanding how societies, polities, and economies really function. We are like physicists at the outset of the nineteenth century, who were poised at a moment in history that would produce Ampères and Faradays.
We ought to be excited, but we aren’t. Trivers again: “Yet discipline after discipline—from economics to cultural anthropology—continues to resist growing connections to the underlying science of biology, with devastating effects.”2
Why the resistance? Because the social sciences have been in the grip of an orthodoxy that is scared stiff of biology.
The Orthodoxy
The core d
octrine of the orthodoxy in the social sciences is a particular understanding of human equality. I don’t mean equality in the sense of America’s traditional ideal—all are equal in the eyes of God, have equal inherent dignity, and should be treated equally under the law—but equality in the sense of sameness. Call it the sameness premise: In a properly run society, people of all human groupings will have similar life outcomes. Individuals might have differences in abilities, the orthodoxy (usually) acknowledges, but groups do not have inborn differences in the distributions of those abilities, except for undeniable ones such as height, upper body strength, and skin color. Inside the cranium, all groups are the same.
The sameness premise theoretically applies to any method of grouping people, but three of them have dominated the discussion for a long time: gender, race, and socioeconomic class. Rephrased in terms of those groups, the sameness premise holds that whatever their gender, race, or the class they are born into, people in every group should become electrical engineers, nurture toddlers, win chess tournaments, and write sci-fi novels in roughly equal proportions. They should have similar distributions of family income, mental health, and life expectancy. Large group differences in these life outcomes are prima facie evidence of social, cultural, and governmental defects that can be corrected by appropriate public policy.
The intellectual origins of the orthodoxy go back more than three centuries to the early days of the Enlightenment and the concept of humans as blank slates. The explicit rejection of a role for biology in the social sciences occurred from the end of the nineteenth through the beginning of the twentieth centuries, with the leading roles played by Émile Durkheim in sociology, Franz Boas in anthropology, and John Watson in psychology.3
The political expression of the orthodoxy had its origins in the mid-1960s with the legal triumphs of the civil rights movement and the rise of feminism. In the beginning, the orthodoxy consisted of specific allegations and solutions: Racism keeps black unemployment high. Sexism stunts women’s careers. Affirmative action and antidiscrimination laws are needed. But the orthodoxy soon began to incorporate an intellectual movement that gained momentum in the mid-1960s with the publication of The Social Construction of Reality by Peter L. Berger and Thomas Luckmann.
The authors were dealing with an ancient problem: Each of us thinks we know what reality is, but different people have different perceptions of it. “The sociologist is forced by the very logic of his discipline to ask, if nothing else, whether the difference between the two ‘realities’ may not be understood in relation to various differences between the two societies,” wrote Berger and Luckmann.4 This beginning, written in plain English, perfectly sensible, morphed during the 1970s and 1980s into the orthodox position that just about everything is a social construct, often argued in postmodern prose that is incomprehensible to all but the elect.5 The sources of human inequalities are artificial, made up, a reflection of the particular reality that a dominant segment of society has decided is the one we must all live by.
As I write, three of the main tenets of the orthodoxy may be summarized as follows:
Gender is a social construct. Physiological sex differences associated with childbearing have been used to create artificial gender roles that are unjustified by inborn characteristics of personality, abilities, or social behavior.
Race is a social construct. The concept of race has arisen from cosmetic differences in appearance that are not accompanied by inborn differences in personality, abilities, or social behavior.
Class is a function of privilege. People have historically been sorted into classes by political, economic, and cultural institutions that privilege heterosexual white males and oppress everyone else, with genes and human nature playing a trivial role if any. People can be re-sorted in a socially just way by changing those institutions.
I have stated these tenets baldly. If you were to go onto a university campus and chat privately with faculty members whose research touches on issues of gender, race, or class, you would find that many of them, perhaps a majority, have a more nuanced view than this. They accept that biology plays a role. Why then don’t they mention the evidence for a biological role in their lectures? Their writings?
A common answer is that they fear that whatever they write will be misinterpreted and misused. But it’s easy to write technical articles so that the mainstream media never notice them. The real threat is not that the public will misuse a scholar’s findings, but that certain fellow academicians will notice those findings and react harshly.
Therein lies the real barrier to incorporating biology into social science. It is possible to survive on a university campus without subscribing to the orthodoxy. But you have to be inconspicuous, because the simplistic version of the orthodoxy commands the campus’s high ground. It is dangerous for a college faculty member to say openly in articles, lectures, faculty meetings, or even in casual conversations that biology has a significant role in creating differences between men and women, among races, or among social classes. Doing so often carries a price. That price can be protests by students, denial of tenure-track employment for postdocs, denial of tenure for assistant professors, or reprimands from the university’s administrators.
The most common penalties are more subtle. University faculties are small communities, with all the familiar kinds of social stigma for misfits. To be openly critical of the orthodoxy guarantees that a vocal, influential element of your community is going to come after you, socially and professionally. It guarantees that many others will be reluctant to be identified with you. It guarantees that you will get a reputation that varies from being an eccentric at best to a terrible human being at worst. It’s easier to go along and get along.
The risks that face individual faculty members translate to much broader damage to academia. We have gone from a shared telos for the university, exemplified by Harvard’s motto, “Veritas,” to campuses where professors must be on guard against committing thought crimes, students clamor for protection against troubling ideas, codes limiting the free expression of ideas are routine, and ancient ideals of scholarly excellence and human virtue are derided and denounced.6 On an individual level, social scientists have valid rationales to avoid exploring the intersection of biology and society. Collectively, their decisions have produced a form of de facto and widespread intellectual corruption.
Archaeological Digs
The good news is that some scholars have been exploring the intersection of biology and society despite the risks—so many that the orthodoxy is in the process of being overthrown. The heavy lifting is being done not within the social sciences, but by biologists and, more specifically, by geneticists and neuroscientists. They have been accumulating data that will eventually pose the same problem for defenders of the sameness premise that Aristotelian physicists faced when Galileo dropped objects from heights. Everyone could see that they didn’t behave as Aristotle’s theory predicted. No one could offer a counterargument. When our understanding of the genome and the brain is sufficiently advanced—and it is approaching that point faster than most people realize—the orthodox will be in the same position. Continuing to defend the sameness premise will make them look silly. It is my belief that we are nearing inflection points and that the triumph of the revolution will happen quickly. The key battles are likely to be won within the 2020s. This book is a progress report.
In the course of writing Human Diversity, it became apparent to me that progress is at strikingly different points for gender, race, and class. The analogy of an archaeological dig of a buried city comes to mind.
The dig for gender is well along. Excavations have been extensive, the city’s layout has been identified, and thousands of artifacts have been found. There’s lots yet to be done, but the outlines of the city and its culture are coming into focus.
The dig for race is in its early stages. Topological analysis has identified a promising site, initial clearing of the site has been completed, and the first probes have e
stablished that there’s something down there worth investigating. Scientists are just beginning excavation.
The dig for class had been largely completed by the end of the twentieth century, and scholars in this century had until recently been kept busy analyzing the artifacts. They are now returning to the site with newly developed tools.
Analogies aren’t precise, but this one explains the organization of the book. I begin with gender differences and devote five substantial chapters to them. A lot has been securely learned about gender differences. Race gets shorter chapters describing how the site was located, how it has been cleared, and the evidence that there’s something down there worth investigating. The chapters on class summarize findings that for the most part have been known for decades.
Why Me?
I am neither a geneticist nor a neuroscientist. What business do I have writing this book?
The answer is that specialists are seldom good at writing overviews of their specialties for a general audience because they know too much—the forest and trees problem. It’s often easier for an outsider to communicate the specialists’ main findings to other outsiders. There are personal reasons as well. I think I’m skilled at making the findings of technical literatures accessible to a broader audience, I enjoy doing it, and I have been a fascinated observer of developments in genetics and neuroscience for years. I’m also at a point in my career when I’m immune to many of the penalties that a younger scholar would risk.
That career includes the firestorm that followed the publication of The Bell Curve more than a quarter of a century ago, an experience that has been on my mind as I have written Human Diversity. How can I avoid a repeat? Perhaps it’s impossible. The background level of animosity and paranoia in today’s academia is much worse than it was in 1994. But here is the reality: We are in the midst of a uniquely exciting period of discoveries in genetics and neuroscience—that’s good news, not bad. My first goal is to describe what is being learned as clearly as possible, without sensationalism. I hope you will finish the book understanding that there are no monsters in the closet, no dread doors that we must fear opening.
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