Human development is gorgeous, Jonathan Weiner writes in Long for the World: The Strange Science of Immortality. The union of sperm and egg results in precise, pre-ordained splitting and budding, creating something predictable yet wholly unique. Human aging is a mess. Our cells break down in a chaotic fashion, and mutation piles upon mutation. Our organs and bones seem to decompose while we still depend on them. It's a cascading decline leading to our inevitable death.
We age because nature loses interest in us, Weiner argues in his new book, an investigation into our ugly endings and what science can do about this disorderly process. He embraces the widely accepted theory postulated by the Nobel Prize winning zoologist, the late Peter Medawar, that evolution's push is to get us up and reproducing. So, for example, we need calcium to help solidify our young bones. But once we're sturdy enough to grab a mate and pass on our genes, we've done our work. Nature doesn't care if some of the calcium then hardens our arteries, causing late-in-life heart attacks.
We care, however, and David Stipp in The Youth Pill: Scientists at the Brink of an Anti-Aging Revolution joins Weiner in exploring the frontiers of the science that is tackling the possibilities of beating aging and cheating death. Weiner brings a lyrical, even meditative, approach to his portraits of the people who are at work tweaking the evolutionary process. Stipp has the workmanlike doggedness of a business reporter as he tracks a field that has migrated from the medical margins toward the scientific mainstream over the past 40 years. Both left me certain that the science of longevity is going to empty neither hospitals nor mortuaries within any of our lifetimes.
Against those who might argue that the last thing we need is yet more old people sucking up resources, the researchers counter that aged populations are a global fact and their goal is to keep people healthy for as long as possible, a benefit not only to each old person, but to society. The surge in the elderly as an age group certainly is impressive. At the beginning of the 20th century, a baby born in the developed world had an average life expectancy of less than 50 years. As the century progressed, advances in public health, widespread vaccination, and the introduction of antibiotics sent infant mortality rates plummeting, which gave more people the chance to get old. By the end of the 20th century, a baby born in the developed world could expect to live to around 80. As Weiner writes, this 30-year addition in life expectancy was "as much time as our species had gained before in the whole struggle of existence." (The outer limit of the human lifespan remains at around 120 years; only a handful have gotten close to this milestone.)
The good news is that more of us are striding, not tottering, into old age, which could be the result of our healthier childhoods. Weiner cites the theory that fewer childhood infections mean we experience less chronic inflammation, an engine of disease. Even so, if we live long enough, eventually for most of us a myriad of possible miseries await, from neurodegenerative diseases like Alzheimer's and Parkinson's to long-simmering but sudden killers like heart attacks and strokes to the runaway frenzy of cancer.
The researchers profiled by Stipp are seeking to master the mechanisms of our decline, so that we can frolic vigorously for eight or nine decades before dying in a brief and efficient fashion. Weiner's muse is prophet, maverick, and crank Aubrey de Grey of Cambridge University, whose vision is more ambitious. A theoretician in the gerontology field, he challenges bench scientists to come up with the necessary biological fixes so humans can reach something close to immortality.
Either quest is a tall one. Both Weiner and Stipp describe the difficulties of establishing scientific credibility in a field that has a disreputable, even ignominious past. In the early 20th century, one rejuvenator transplanted ape testicles into men. Another, Eugen Steinach, performed vasectomies as a way to restore flagging virility. Sigmund Freud is said to have been "Steinached," as was William Butler Yeats—a snip for that "tattered coat upon a stick." In that era, the fix for female revitalization was irradiating the ovaries.
But by the 1970s a handful of serious scientists had begun studying other species' lifespans, with methods that ranged from documenting them in the wild to selectively breeding lab animals to identify longevity genes. "Comparative gerontology" looks at the amazingly diverse aging styles in the animal kingdom. Fruit flies live weeks; the quahog can live four centuries. Mice and rats live only a few years, even in the cosseted safety of the laboratory, getting scruffy and sluggish in the process. It's another rodent that entrances researchers of longevity. The naked mole rat spends decades digging burrows while barely showing any sign of age (scientists call this "negligible senescence") until dropping dead of unknown causes. If only we could get old like naked mole rats, the cosmetic rejuvenation industry would go out of business.
Of course, extrapolating from animals to humans is always a big leap, but almost three-quarters of a century ago, once-forgotten research on the life-lengthening effects of manipulating animals' environment turned up something provocative. In the 1930s, a nutrition researcher at Cornell, Clive McCay, did a four-year study which demonstrated that putting rats on a near-starvation diet enhances their health and vastly extends their life. This was, Stipp writes, an astounding, heretical finding: "McCay showed that the rate of aging is incredibly plastic, and that it's supremely simple to brake it in animals whose inner workings aren't all that different from ours."