GoKawiilAnalyses of scientific evidence led doctors to recommend that babies sleep on their backs.Credit: Yamaguchi Haruyoshi/Corbis/Getty
Beyond Belief: How Evidence Shows What Really Works Helen Pearson Princeton Univ. Press (2026)
Cementing the use of evidence in health and public policy has taken decades of challenging work. Fifty years ago, physicians commonly thought that babies should sleep on their fronts — advice popularized by US paediatrician Benjamin Spock and others. It took a synthesis of observations and case studies to show that this was wrong: babies should sleep on their backs to minimize the risk of sudden infant death syndrome (SIDS). More than 50,000 deaths across the United States, Europe and Australasia could have been prevented had this evidence been combined and put to use sooner.
Make science more reliable: study people as they go about their lives
Beyond such data, the randomized controlled trial (RCT) is usually the gold standard for medical or public-policy evidence. Including a control group against which to compare interventions shows what would have happened without it. Combining many trials into a meta-analysis gives practitioners and policymakers more confidence in whether a drug or treatment works.
In Beyond Belief, journalist and science communicator Helen Pearson (who is an editor at Nature) presents an accessible account of how such practices spread. Covering topics from policing to child development, she focuses on outcomes that everyone cares about, be those safer neighbourhoods or better childbirth procedures.
This book is not a technical treatise, and nor should it be. As researchers know, the details of RCTs soon get technical once their basic principles have been explained. But Pearson pulls off a narrative feat. Anyone can read and enjoy the book, yet there are nuggets for experienced readers. The background research is impeccable. The only slip I noticed is the statement that “by 1964, around 25 out of every 1,000 children in the United States were dying from sudden infant death syndrome or SIDS” — in fact, this number is the rate of deaths from all causes, with SIDS being a small fraction.
Facing the facts
The book shares many examples of successes, in which solid evidence has corrected long-accepted bad practice. A 2002 Women’s Health Initiative trial1 showed that hormone replacement therapy (HRT), widely prescribed to prevent heart disease on the basis of previous observational studies2, actually increased the risk of cardiovascular disease and breast cancer.
Similarly, a systematic review of nine randomized trials3 done from the 1970s to the 1990s showed that an anti-crime programme adopted by many US states backfired in practice. Known as Scared Straight, the initiative involved sending children at risk of criminality into prisons to speak with incarcerated people. But, in the end, participants were more likely to offend than those in the control group.
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