In HOTWIRED: How the Hidden Power of Heat Makes Us Stronger (Harper Wave; on sale 3/17/2026), Bill Gifford-science journalist and coauthor of the #1 New York Times bestseller Outlive-delivers a groundbreaking look at the science of heat adaptation and sweat therapy such as sauna, revealing how we can unlock our forgotten evolutionary superpowers. Drawing on pioneering research in evolutionary biology, thermal physiology, and mental health, Gifford explores how humans evolved to thrive in the heat-and how modern life has disconnected us from this advantage. Blending innovative science, personal experiences, and actionable insights, Gifford shows how targeted heat exposure can boost resilience, longevity, and even happiness by activating the body's innate survival mechanisms.During his two-year exploration of the power of heat, Gifford sweated all over the world and dug in deep with experts, athletes, workers, scientists, sauna addicts, and more. His fascinating journey included:· Immersing himself in local sauna cultures around the world, from Finland to Bucharest to Minnesota to New York City, where he bonded with complete strangers in a social sauna and felt the power of communal wellness· Serving as a test subject in a cutting-edge heat lab dedicated to pushing the limits of heat adaptation for athletes and to protecting workers from heatstroke· Putting the science of heat training into practice on a 100-mile bike ride under a scorching Texas sun