You have full access to this article through your institution. Hello Nature Readers, would you like to receive this report in your inbox for free every day? Register here. Researchers are trying to produce human sperm (shown here in a colored electron microscope image) from stem cells in the laboratory.Credit: Juergen Berger/Scientific Photo Library Scientists
Analyzes of the scientific evidence led doctors to recommend that babies sleep on their backs.Credit: Yamaguchi Haruyoshi/Corbis/Getty Beyond Credibility: How Evidence Shows What Really Works Helen Pearson Princeton University. Press (2026) Consolidating the use of evidence in health and public policy has required decades of challenging work. Fifty years ago, doctors used to think that