Even that may be optimistic. Neuroscientists have found evidence of a “genetic clock” that controls gene expression in the brain and central nervous system from infancy through elderhood. Even if we could arrest all of the aging processes in the rest of the body, degradation of memory and other neural functions will continue. There is considerable evidence that exercising the brain by learning new skills can slow or arrest age-related degradation, but ultimately people lose brain functions as they age even absent of dementia, Alzheimer’s disease, or cumulative brain trauma. Reversing that will literally require understanding and refactoring the gene expression processes in the brain which we are nowhere near about to do with any useful degree of fidelity.
Improving quality of life through the elderhood, on the other hand, is a largely tractable problem. There is considerable evidence that many of the chronic conditions we experieince as “normal aging” are at least in part a result of modern diet and sedentary lifestyle, including changes that affect the intestinal biome. Societies with the most per capita long lived people—the so-called “Blue Zones”—have commonalities such as a largely minimally processed plant-based diet (but in which whole animal products—not just muscle tissue but saturated fats, rendered connective tissue and bones—are also reguarly consumed, except the Seventh Day Adventists), regular and vigorous physical activity, and strong social and familial bonds are inherent aspects of life. These people don’t just live longer, either; they have fewer incidences of serious mental illness such as depression and anxiety, statistically lower incidence of chronic diseases such as many forms of cancer, and are generally physically active and mentally alert into their eightes or nineties as a rule.
While medical science has turned to largely pharmaceutical treatment to deal with the supposed afflictions of age with varying degrees of practical effectiveness and often side effects which require more treatments, significant lifestyle changes may allow most people who do not have any underlying illness or defect to live a health and active life many decades past what we think of as “middle age”. This is not to detract from the benefits of vaccination, antibiotic treatments, synthetic insulin for Type I diabetes,
and cancer therapies, among other benefits of modern medicine, but trying to treat poor lifestyle choices with drugs like statins and beta blockers is really just covering the underlying problem (poor nutrition, lack of exercise, ineffective coping mechanisms for stress).
With a combination of lifestyle modifications and gene or hormone therapies we could probably extend the typical lifespan to somewhere around 90 to 100 years, but at some point somatic and mental systems are just going to start degrading beyond any ability to treat them due to “preprogrammed” apoptosis. Extending maximum human lifespan to signficantly beyond 120 years will require a retooling of the genome and fine-grained control of the epigenome to arrest or reverse normal processes of aging. It isn’t clear that we could engineer human beings to live hundreds or thousands of years without aging with radical alteration of thousands of genes involved in nearly every aspect of the human body.
Stranger