Today’s review is of my favorite book about aging so far, Steven Austad’s Why We Age: What science is discovering about the body’s journey through life. Dr. Austad’s style is clear and approachable, even a bit folksy. He creates the kind of engaging, personal narrative that Dr. Sinclair often achieved in Lifespan, but with none of the self-promotion. His explanations are easily understood without sacrificing accuracy or an acknowledgement of uncertainty.
Dr. Austad also takes an approach beloved by skeptics, explicitly stating his goal is to separate “substance and reasonable speculation from myth and wishful thinking.” He begins with ideas that are popular but not as accurate or powerful a representation of reality as often thought and then shows their limitations and the evidence against them. But he does an unusally effective job of this in that he creates authentically compelling stories for these ideas even when he ultimately debunks them. Often, he finds the useful bits of outdated theories and illustrates how they form part of a chain of reasoning and experimentation that leads forward, rather than reinforcing the narrative of science as a series of failures or flip-flops.
One of the myths he punctures is the notion of “special” populations of humans with unusually long lives. Often such populations are studies with an eye to understanding what makes them live so much longer than the rest of us. Austad shows that these pockets of exceptional longevity are based mostly on a combination of poor record keeping and excessive credulity. A strong correlation with lifespan turns out to be the literacy rate, since people who can’t read or keep accurate vital records can easily misremember or misrepresent their longevity.
The book also does a good job of challenging common assumptions and practices in the aging field. There is an interesting discussion of why lifespan itself isn’t a great measure of aging. We have extended average lifespan significantly by reducing causes of illness and death in children, but that hasn’t really changed the rate at which we age or affected maximum lifespan much. Lifespan and disease incidence may both be confounded by factors other than biological aging per se.
The age-specific mortality doubling time might be a better measure of the impact of specific interventions on the rate of aging, even if extended lifespan and healthspan are the real-world outcomes we are seeking. And given that reduction of specific causes of mortality individually have fairly small effects on lifespan, focusing on the rate of aging and measuring it accurately is critical.
Dr. Austad also introduced me to my new favorite phrase: “testosterone dementia.” In a cogent discussion of the evolution of aging, he touches on sex differences in mortality and longevity. One feature of this that readily appears is the increased non-disease-related mortality of young males, in humans, certainly, but in many other mammals as well. Often this involves behavioral risk factors, and as someone who cringes at memories of my youthful risk-taking, I appreciate the humorous but apt description of this particular sex-associated behavioral pattern.
Why We Age ends with a review of popular proposed methods for retarding aging and the state of the evidence for these. The book was written in 1997, so this is not entirely up to date, but it is still an excellent example of skeptical optimism—evaluating proposed interventions in a critical, evidence-based way even when one is personally hopeful about them.
The age of the book is one of its few weaknesses. Additionally, there is a rather long chapter on the subject of menopause, which includes some conclusions not consistent with current evidence-based guidelines. While the subject of reproductive senescence is an interesting and important one, this section hasn’t aged as well as the rest of the book.
On the whole, however, this is an excellent introduction to aging biology for the general reader: readable and engaging, accurate without being excessively detailed, skeptical yet positive, and much less focused on the personality and achievements of the author than the others I have reviewed.