Why Trust Science?

by Naomi Oreskes

  Finally, these geneticists noted, to improve the world through selection would require agreement about what constituted improvement, something that was by no means apparent, particularly if the goals of selection were social ones. In their view, the most important genetic characteristics one might want to try to foster would be those for health, for the “complex called intelligence,” and “for those temperamental qualities which favour fellow-feeling and social behavior, rather than those (to-day most esteemed by many) which make for personal ‘success,’ as success is usually understood at present.”96 So despite expressing in-principle support for eugenic ideals, they opposed eugenic proposals in practice. The prerequisite for improving the quality of the world’s population was improving the social conditions of the world.97

  The socialist geneticists’ opposition to eugenics was rooted in their politics, but one did not have to be a socialist (or social scientist) to recognize flaws in eugenic research. In particular, many geneticists pointed out the fallacy of conflating genes with outcomes. Garland Allen has stressed that the great British statistician Karl Pearson, who was a eugenicist, strongly criticized the work of the ERO as “carelessly and sloppily conceived and executed, and lack[ing] any semblance of normal scientific rigor.”98

  Herbert Spencer Jennings was an American geneticist at Johns Hopkins University known for his 1930 book, The Biological Basis of Human Nature.99 While the title might suggest an argument for genetic determinism, the book presented the scientific case for the interaction of genes and environment. Against the genetic determinists, Jennings wrote:

  A given civilization is the outgrowth of the interaction of the genetic constitutions present in the population, with the environment—including knowledge, inventions, traditions—of that population. By changes in the latter set of factors enormous differences have in the past been made in the cultural system.… No cultural system is the outgrowth of genetic constitution alone.100

  And against the environmental determinists:

  [The environmental determinist argues that] by subjection to adequately diverse environments, diverse training and instruction, any of [a group of people] can be made … into “doctor, lawyer, merchant, chief” … Biology has no proper quarrel with such an assertion. What an enlightened view of biology would add … is this: While any of the normal individuals, taken early and properly guided, could be made into physicians, it would take different treatment to accomplish that end in the different individuals.101

  Eugenicists had committed numerous logical and methodological fallacies, including being overly influenced by implicit assumptions (“underlying … but never stated”), ignoring evidence that did not support their positions, and persisting in “mistaken conclusions after the discovery that they are mistakes.”102 Jennings was particularly critical of what he called “the fallacy of non-experimental judgments,” noting that precisely because nearly everyone had an opinion on heredity and evolution, it was “essential to set aside prior views and build one’s opinions on the basis of experimental evidence.” But this was just what most eugenicists failed to do; they ran with their priors and ignored disconfirming evidence.103 Jennings also noted the widespread use of what today we would call the fallacy of the excluded middle—to assume that because some traits have been shown to be inherited, all traits are inherited, and vice versa regarding the environment—and, in language reminiscent of T. C. Chamberlin, “The fallacy of attributing to one cause what is due to many causes.”104

  For Jennings it was obvious that the answer to the nature/nurture debate was both/and. He made the point in a 1924 article by analogy to material objects:

  What happens in any object—a piece of steel, a piece of ice, a machine, an organism—depends on the one hand upon the material of which it is composed [and] on the other hand upon the conditions in which it is found. Under the same conditions objects of different material behave diversely; under diverse conditions objects of the same material behave diversely.… Neither the material constitution alone, nor the conditions alone, will account for any event whatever; it is always the combination that has to be considered.

  And so it was for organisms. “The individual is produced by the interaction of genes and environmental conditions; so that the same set of genes may yield diverse characteristics under diverse environments.” Eugenics was doomed to fail, because “behavior is bound to be relative to environment, it cannot be dealt with as dependent on genes alone. A given set of genes may result under one environment in criminality; under another in the career of a useful citizen.”105

  Jennings is but one example; if space permitted we could easily multiply his critique. The Nobel Laureate T. H. Morgan, famous for his work on the genetics of fruit flies, stressed in the 1920s that the problems eugenicists proposed to repair would likely be more quickly remedied through social reform than through selective breeding.106 Many non-scientists also raised methodological and moral objections.107 (And there were objections raised in other countries that I have not considered here.)108 The important point here is that eugenics as a political movement in important ways conflicted with scientific understanding, and it is simply not correct to say that there was a scientific consensus on eugenics.109

  Now let us consider an example where there was a consensus, but one that ignored or at least discounted important, significant evidence.

  Example 4: Hormonal Birth Control and Depression

  Many women have had the experience of becoming depressed or melancholic on taking the contraceptive pill, many doctors are aware of their patients’ experience, and many scientific studies have affirmed this link. Indeed, some of the earliest studies of the effects of the Pill in the late 1950s noted side effects including “crying spells” and “irritability,” and the package insert that now comes with it states that one of the known side effects is “mental depression” (see fig. 1).

  FIGURE 1. Detail of package insert for the oral, hormonal contraceptive ORTHO TRI-CYCLEN® Lo Tablets (norgestimate/ethinyl estradiol) showing “mental depression” among the list of potential adverse reactions, which are “believed to be drug-related.”

  Recently, there was a flurry of media attention about a new study demonstrating that the Pill can cause depression.110 Physicians lauded the study, and the media presented the result as a novel finding.111 My own daughter, however, asked me on the day the coverage hit the media: How is this news? She knew that the Pill could cause depression, because I had told her so.

  I have no history of depression—no family history of depression or mental illness of any sort—but when I was in my midtwenties, I experienced a sudden and peculiar bout of extreme melancholy. I lost my energy for daily tasks, lost interest in my work, and, after about six weeks, found myself having trouble getting out of bed. And yet, in other respects my life was going well. I was in my second year of graduate school, had done very well in my first year, was working on an exciting project for which I had adequate funding, and had met a very nice man who would soon become my husband (and to whom I’ve now been married for more than thirty years).

  I went to counseling at a campus health center, and I was lucky. The female counselor asked me straight away: Are you on the Pill? The answer was yes. I explained that I had recently returned from Australia, and because Australia at that time had free health insurance, including prescription drugs, I had bought a year’s worth before I left. But the particular formulation that I had been prescribed in Australia was not available in the United States, so when the year was up I had to switch to another type. That had occurred two months before. The onset of my depression began shortly after I had started this new form of the Pill. The therapist told me that the type of pill I was now on—a combination formulation—was well known to be more likely to cause depression than some other options. I stopped the drug immediately and my recovery began nearly as immediately. Within a few weeks I was back to my normal self, I thanked the therapist, and went on to a successful academic career and life.


  My experience can be dismissed as “just an anecdote,” but I prefer to view it as a clinical study in which n = 1. The more important point is that many women have had such experiences and reported them to their physicians and therapists. The website Healthline.com, which claims to be the “fastest growing consumer health information site,” notes that “depression is the most common reason women stop using birth control pills.”112 Moreover, like me, many women have bounced back to normal when they stopped taking the Pill or switched to other formulations. And these case reports have spurred numerous scientific studies. As one physician recently wrote, “decades of reports of mood changes associated with these hormone medications have spurred multiple research studies.” So my daughter was correct to ask: how was this new study news?

  One answer was offered by Monique Tello, a practicing MD, MPH, who writes for the Harvard Gazette: “The study of over a million Danish women over age 14, using hard data like diagnosis codes and prescription records, strongly suggests that there is an increased risk of depression associated with all types of hormonal contraception.” Previous studies, in contrast, were all “of poor quality, relying on iffy methods like self-reporting, recall, and insufficient numbers of subjects.” The authors of the new study concluded that previously it had been “impossible to draw any firm conclusions from the research on this subject.”113

  It is hard to argue with a study of over one million women. It is also hard to argue with any study done in Denmark, which has a national health care database covering every Danish citizen and thus allows researchers to correct for sampling biases and other confounding effects. It is thanks to Denmark that we can say with confidence that children who are fully vaccinated according to prevailing public health recommendations do not suffer autism at greater rates than those who are not.114 So, three cheers for Denmark. Three cheers, as well, for this big, new convincing study. But note the explanation of why it took so long to come to this point: the lack of “hard data like diagnosis codes and prescription records.” Previous studies, we are told, relied on “iffy methods like self-reporting, recall, and insufficient numbers of subjects.”115

  The term “hard data” should be a red flag, because the history and sociology of science show that there are no hard data. Facts are “hardened” through persuasion and their use. Moreover, remarks of this type raise the question of why some forms of data are considered hard and others are not. Just look at what is being considered hard data here: diagnosis codes and prescription records. Many people would say hard data are quantitative data, but neither of these constitutes a measurement: they are the subjective judgments of practitioners and the drugs they choose to prescribe in response to those judgments.116 Moreover, there is a substantial literature on misdiagnosis in medicine, and on the distorting effects of pharmaceutical industry advertising and marketing on prescribing practices.117 Given what we know about medical practice and its history, the idea that diagnosis codes and prescription records should be taken as hard facts seems almost satirical.

  But it gets worse: the study authors accepted the reports of doctors—their diagnosis codes and prescription records—as facts, whereas the reports of female patients were dismissed unreliable—in Tello’s words: “iffy.” Bias—either against women or against patients—is clearly on display. But here is the key point: the conclusion of the Denmark study is the same as all those iffy, self-reports from female patients. If the new study is correct, then the allegedly iffy self-reports were correct all along.

  These self-reports involved millions of women, too. The Pill has been on the market in the United States and Europe since the early 1960s. According to the CDC, during period 2006–10, over ten million American women took the Pill.118 According to the World Health Organization, over one hundred million are currently taking it worldwide.119 While self-reporting does not offer a good basis for an accurate quantitative assessment of risk of depression caused by hormonal contraception, it surely offers important qualitative evidence. It seems extremely unlikely that all the women who reported mood changes while on the Pill were simply confused or making it up.

  In fact, the connection between hormonal birth control and depression has been known almost as long as the Pill has been on the market. In 1969, feminist journalist Barbara Seaman published The Doctor’s Case against the Pill, a book that helped to launch the women’s health movement. Seaman’s book made women and doctors around the country aware of the serious health risks of the Pill as it was then formulated, and led to congressional hearings resulting in the first package insert to warn against risks involved with a prescription medication. Chapter 15 of her book was entitled “Depression and the Pill,” and it began:

  Psychiatrists were among the first doctors to persuade their own wives to stop using birth control pills. Finely tuned to emotional feedback, they did not take long to notice certain adverse reactions in their wives and daughters, patients and friends. The effects that were the most obvious ranged from suicidal and even murderous tendencies to increased irritability and tearfulness.… A few pill-users have become so hostile, suspicious and delusional that they have seriously thought of murdering—or have actually attempted to murder—their own husbands and children. Others attempt to commit suicide and some have succeeded.120

  Within a few years of the Pill coming on the market, adverse mental health effects had been widely reported. A 1968 study in the United Kingdom looked at 797 women who took oral contraceptives; many reported emotional side effects and two committed suicide.121 By 1969 British researchers had found that one in three Pill users experienced personality changes; three in fifty who were studied became suicidal. A US study by researchers at the University of North Carolina School of Medicine found that 34% of otherwise healthy young women reported depression after starting on the Pill. These studies did not include control groups, but one in Sweden compared two groups of post-partum women, matched with respect to social background, previous history of depression, and other factors. It found significantly higher rates of psychiatric symptoms in women who went on the Pill after giving birth than in the group who used other forms of birth control.

  We cannot judge from Seaman’s account how good any of these studies were; her point was that to the extent that scientists had examined the question, they had found evidence to support women’s accounts, accounts that formed the emotional heart of Seaman’s story. She told of women who became agitated and disorganized; who experienced panic attacks in movie theatres; who set “accidental” fires; who found themselves weeping uncontrollably for no apparent reason; and who felt themselves to be on the verge of breakdown. Some of these women may have been depressed for other reasons, but Seaman supported their accounts with testimony from psychiatrists. Women’s stories formed the emotional center of the book, but doctor’s stories provided the intellectual center. It was not the patient’s case against the Pill, but the doctor’s case.

  With respect to the mental health effects, the key doctors were psychiatrists, to whom women had gone for help after becoming depressed on the Pill, or who noticed changes in their wives and friends and in patients they had been seeing for some time and knew well. Seaman quoted one Manhattan psychiatrist describing the resistance he initially encountered from other doctors:

  My fights with the gynecologists began in 1963 [three years after Enovid, the first oral contraceptive, was approved.]122 I’d been seeing one patient twice a week for two years.… She was tough as nails … Her father had been an alcoholic. She’d fought her way to the top as a fashion model.… She’s one of the most sensible patients I ever had. Exploitative? Yes. Neurotic? A little. Depressed? Never. Eight days after this patient went on the pill, she arrived for her appointment and wept through the whole session. The same thing happened the next time and the next … She talked about “giving up” and “ending it all.” I suggested that she get off the pill. We’d see what happened then. She did. The next time I saw her she was her old self. But then came the first in a s
eries of calls from her gynecologist. In essence what he had to say was, “You stick to your own unraveling or whatever it is you do, and let me take care of my knitting. Birth control is not a psychiatrists’ province.”123

  (Eventually, gynecologists would accept there was a pattern; this particular gynecologist was convinced by the psychiatrist and began to send him patients for Pill-induced depression.)

  Other psychiatrists told similar stories. Patients they had known for years were suddenly different; or patients were sent by their families because of sudden, frightening changes. The Atlanta physician John R. McCain presented a paper at the New England Obstetrical and Gynecological Society warning that the mental health effects of the Pill were “among the complications which seem to have the most serious potential danger.”124 The good news, many doctors noted, was that when women went off the Pill, the abatement of symptoms was as fast as the onset. This, of course, was further evidence that the Pill was a factor in their condition.

  In many of these stories, women noted that their mood swings and depression were similar to what they had experienced when they were pregnant or just after giving birth—and doctors had rarely doubted that hormones had something to do with those experiences! Among the various stories recounted in the book, my personal favorite is this one: “When I was on the pill,” one psychiatrist’s wife reported, “I hardly ever got off the couch except to slap one of the children.”125

  In the years that followed, scientists and physicians undertook studies of the mental health effects of the Pill. But considering how many women have taken the Pill, the total number of studies is startling modest. A quick PubMed search in 2016 on hormonal birth control and depression/mood or psychological disorders/libido changes found twenty-seven papers. This may be an underestimate—other key words or phrases might have turned up more, and mood changes may also have been detected in studies concentrating on other things—but compare this to another issue that I have studied: climate change. In my 2004 study of climate science, I used a sample of just under one thousand articles to estimate the state of scientific opinion.126 That sample came from a population that was estimated to be over ten thousand papers. Since that time, at least that many more have been published.127 Given that over one hundred million women are on the Pill today, doesn’t it seem troubling that there are so few studies on something that was recognized as a potentially serious problem more than fifty years ago?