Emma Morano turned 117 on Tuesday. The Italian woman is, as far as we know, the oldest person in the world and the only living person who was born in the 1800s. The secret for her longevity? Eating three raw eggs a day and being single since 1938. The person known to have lived the longest ever was Jeanne Calment, who died in 1997 at 122 years of age.

In October, Nature published an article, "Evidence for a limit to human lifespan," by three researchers associated with the Albert Einstein College of Medicine in the Bronx. Noting that the longest known lifespan has not increased since the 1990s, they argue that there is a fundamental limit to human longevity. The occasional outlier aside, they think that limit is about 115 years.

Maybe, maybe not. In the 21st century, almost everything that kills people, except for accidents and other unintentional causes of death, has been classified as a disease. Aging kills, so it's past time to declare it a disease too and seek cures for it.

In 2015, a group of European gerontologists persuasively argued for doing just that. They rejected the common fatalistic notion that aging "constitutes a natural and universal process, while diseases are seen as deviations from the normal state." A century ago osteoporosis, rheumatoid arthritis, high blood pressure, and senility were considered part of normal aging, but now they are classified as diseases and treated. "There is no disputing the fact that aging is a 'harmful abnormality of bodily structure and function,'" they note. "What is becoming increasingly clear is that aging also has specific causes, each of which can be reduced to a cellular and molecular level, and recognizable signs and symptoms."

So why do people age and die? Basically, because of bad chemistry. People get cancer when chemical signals go haywire enabling tumors to grow. Heart attacks and strokes occur when chemical garbage accumulates in arteries and chemical glitches no longer prevent blood cells from agglomerating into dangerous clumps. The proliferation of chemical errors inside our bodies' cells eventually causes them to shut down and emit inflammatory chemicals that damage still healthy cells. Infectious diseases are essentially invasions of bad chemicals that arouse the chemicals comprising our immune systems to try and (too often) fail to destroy them.

Also in 2015, another group of European researchers pointed out that we've been identifying a lot of biomarkers for detecting the bad chemical changes in tissues and cells before they produce symptoms associated with aging. Such biomarkers enable pharmaceutical companies and physicians to discover and deploy treatments that correct cellular and molecular malfunctions and nudge our bodies' chemistry back toward optimal functioning. As a benchmark, the researchers propose the adoption of an "ideal norm" of health against which to measure anti-aging therapies. "One approach to address this challenge is to assume an 'ideal' disease-free physiological state at a certain age, for example, 25 years of age, and develop a set of interventions to keep the patients as close to that state as possible," they suggest.

Most people's body chemistry is at its best when they are in their mid-twenties. In fact, Americans between ages 15 and 24 are nearly 500 times less likely to die of heart disease, 100 times less likely to die of cancer, and 230 times less likely die of influenza and pneumonia than people over the age of 65 years. For lots of us who are no longer in our twenties, television talk show host Dick Cavett summed it up well: "I don't feel old. I feel like a young man that has something wrong with him."

Meanwhile, lots of progress has been made toward ameliorating many of the diseases whose prevalence increases with aging. For example, the five-year survival rate for cancer patients in 1975 was 50 percent; today it is about 68 percent. The annual rates of heart disease and strokes in the U.S. have fallen from 500 and 130 per 100,000 respectively in 1970 to about 175 and 35 per 100,000 today. Since 1999, the influenza and pneumonia death rates have dropped from 24 to 16 per 100,000. Additionally, the flu and pneumonia death rate has been almost cut in half for Americans over age 65 since the 1980s.

Needless to say, if people's bodies remained young, the toll from those maladies would be far less. The good news is that researchers are identifying more and more of the chemical glitches that contribute to aging and are working on treatments to slow, stop, and even reverse it. One of the more promising areas of research focuses on repairing and replacing mitochondria, the thousands of tiny energy-producing organelles inside each of our cells.

Mitochondria mutate over time, becoming less efficient and flooding our cells with damaging chemicals. In November, researchers at Caltech and UCLA genetically boosted the activity two genes that detect and destroy mutated mitochondria in the muscles of fruit flies. The technique reduced mutated mitochondrial DNA (mtDNA) from 75 percent to 5 percent.

"We know that increased rates of mtDNA mutation cause premature aging," explained the Caltech biologist Bruce Hay in a press release. "This, coupled with the fact that mutant mtDNA accumulates in key tissues such as neurons and muscle that lose function as we age, suggests that if we could reduce the amount of mutant mtDNA, we could slow or reverse important aspects of aging."

As we age, the number of stem cells in our bodies decline. (Stem cells are the reservoirs that produce new healthy cells to replace those that die or become senescent.) Recent research boosting the amount the coenzyme nicotinamide adenine dinucleotide (NAD+) rejuvenates stem cells. Supplementation using a NAD+ precursor, nicotinamide riboside, promoted muscle healing and the generation of new brain cells in aged mice. Consequently, a February2016 review of NAD+ research in Science observed that studies of the coenzyme "have ignited considerable interest in manipulating NAD+ concentrations in therapeutic efforts aimed at disease prevention and life-span extension." In October, a clinical trial found that people suffered no ill effects from taking nicotinamide riboside and that it did boost their NAD+ levels.

As we age, our immune systems wear out and become less able to protect us from invasive microbes and to destroy cancerous cells. Research in 2014 using the experimental drug rapamycin found that it significantly boosted the immune response in people over age 65. "It sets the stage for using this drug to target aging, to improve everything about aging," said Nir Barzilai, head of the Institute for Aging Research at New York City's Albert Einstein College of Medicine, at the time.

"Classifying aging as a disease," write the biogerontologists Alex Zhavoronkov and Bhupinder Bhullar, "will result in new approaches and business models for addressing aging as a treatable condition, which will lead to both economic and healthcare benefits for all stakeholders." It is well past time to get on with it—none of us are getting any younger.