Why do we age? New popular science book introduces the latest findings in longevity research

In her new book, Associate Professor Juulia Jylhävä from the University of Oulu explores the latest breakthroughs in aging research. The book brings much-needed evidence-based insights to the fast-paced health debate.
Miksi vanhenemme -kirjan kansikuva ja kirjailija Juulia Jylhävä.
Juulia Jylhävä wants to deepen our understanding of why we fall ill as we age and why some people maintain their health and functional capability for an exceptionally long time. Cover designer: Tuomo Parikka, author photograph: Marjaana Malkamäki / Tammi.

Why do some people age faster than others? Which of us will live a long life? Can biological age be influenced—and if so, how?

Juulia Jylhävä, Associate Professor specialising in ageing research at the University of Oulu, answers these questions in her new popular science book Miksi vanhenemme: Elinkaaren biologia tieteen valossa (Why We Age: The Biology of the Lifespan in the Light of Science).

In the book, Jylhävä makes this complex and rapidly evolving field accessible to anyone interested in health, aging, and evidence-based information. She explains how genes, lifestyle, and the environment affect how our bodies age, and reveals the tools used to measure actual biological age far more accurately than calendar years.

"I hope the book helps readers understand that aging isn't simply an inevitable decline chugging along like a train. It is a biological process that can be studied, and its mechanisms can be influenced through lifestyle choices," Jylhävä says.

Jylhävä aims to bring evidence-based knowledge to the ongoing debate and social media hype surrounding aging, particularly ways to slow it down. She highlights, for instance, the significant influence social media figures have over people interested in biohacking or their health.

"I believe that today, we need more research-backed facts and less hype."

In her work as an Associate Professor in the Health Dimensions research programme, Jylhävä investigates the mechanisms of biological aging, seeking to understand why some people accumulate a range of illnesses as they grow older while others preserve their health and independence exceptionally late into life.

Writing the book prompted her to view her research topic from a broader perspective and realize just how much there is left to learn about aging.

"Research data has increased exponentially in recent years, but at the same time, it has become clear just how complex a phenomenon aging is, and how deeply various biological mechanisms interact and interconnect," Jylhävä explains.

Jylhävä, J. (2026). Miksi vanhenemme: Elinkaaren biologia tieteen valossa. Tammi.

Created 20.8.2026 | Updated 20.8.2026