The reversal of aging and by extension the increase in life expectancy in the wake of scientific discoveries are often at the center of discussions, but also the effects that such a development could have on social issues such as inequality.

Already, people are living twice as long as they did 150 years ago because of increased knowledge about disease and its spread, reports the CNN hosting an interview with Nobel Prize winning molecular biologist, Venki Ramakrishnan.

THE Ramakrishnan shares his views on the reality of aging, death and immortality.

CNN: What is aging? How does it lead to death?

Venki Ramakrishnan: Aging is the accumulation of chemical damage to the molecules inside our cells, which damages the cells themselves, and therefore the tissue, and then ultimately us as an organism. Paradoxically, we begin to age when we are in the womb, although at that point, we grow faster than we accumulate damage. Aging happens throughout our lives, from the beginning.

The body has evolved many mechanisms to repair age-related damage to our DNA and any poor-quality proteins we produce. Without ways to fix these kinds of problems, we would never live as long as we do. However, over time, the damage begins to exceed our ability to repair.

Think of the body as a city containing many systems that must work together. Once an organ system critical to our survival fails, we die. For example, if our muscles become so weak that our heart stops beating, it cannot pump the blood that contains the oxygen and nutrients our organs need, and we die. When we say someone dies, we mean his death as a person. In fact, when we die, our organs are alive. This is why organs from accident victims can be donated to transplant recipients.

CNN: Does the human lifespan have a fixed limit?

Ramakrishnan: The lifespan of all organisms ranges from a few hours or days for insects to hundreds of years for some whales, sharks, and giant tortoises. A layman might assume that it is predetermined for all life forms to die once they reach a certain age. But biologists do not believe that aging and death are programmed in the sense that a fertilized egg is programmed to develop into a human being.

Instead, evolution has optimized the equation that affects lifespan. Larger animals tend to live longer. A small animal that is more likely to be eaten by a predator, starve, or die in a flood makes no sense for evolution to waste resources repairing the damage necessary to keep it alive longer. Instead, evolution chooses to grow fast and mature faster so it can reproduce and pass on its genes.

A larger animal, staying alive longer will give it a better chance of finding a mate with whom it can produce more offspring during your longer life. Lifespan is all about evolution by maximizing the chances of passing on one’s genes. In humans, this well-tuned balance of resources gives us a maximum lifespan of about 120 years. But that doesn’t mean we can’t change biology and interfere with these aging processes and perhaps extend our lives. Like many senior scientists, I believe it is possible. I do not, however, share their optimism about how feasible such interventions would be.

CNN: Who has lived the longest so far?

Ramakrishnan: The oldest person for whom we have reliable records was a French woman named Jeanne Calment, who died in 1997 at the age of 122. She smoked all her life except for the last five years and ate over two kilos of chocolate every week. But I wouldn’t recommend these particular habits for longevity, except maybe chocolate.

CNN: Can the aging clock ever be turned back?

Ramakrishnan: The aging clock runs backwards, every generation. Although a child is born from the cells of adult parents, the child still starts at age zero. A child born to a 40-year-old woman is not 20 years older than a child born to a 20-year-old woman. Both start from scratch. So, at some level, the aging clock can be reversed.

There is also cloning. While Dolly, perhaps the most famous cloned sheep, was sick and died at about half her normal age, other cloned sheep went on to live normal lives. This has convinced some that resetting the aging clock must be possible. While tricking adult cells into becoming embryonic and starting to grow again has been successful, practical difficulties make cloning very inefficient. Many cells have accumulated too much damage, which requires a huge number of experiments to develop a single animal.

Experiments in mice, meanwhile, have used cellular reprogramming so that cells can partially revert to growth in order to regenerate tissue. By converting the cells to a slightly earlier state, scientists have created mice with better blood markers and improved fur, skin and muscle tone. Despite all the research in this area, I’m not sure how easy it will be to translate into something useful for humans.

CNN: Your father just turned 98. What effect will his good health have on your life? How much is aging and longevity influenced by genetics?

Ramakrishnan: There is a correlation between the ages of parents and their children, but it is not absolute. A study of 2,700 twins in Denmark showed that heredity, meaning how much longevity is due to our genes, accounted for only about 25% of lifespan. However, the researchers discovered that a mutation in a single gene can double the lifespan of a certain type of worm. Clearly there is a genetic component, but the effects and implications are complex.

CNN: What does cancer science reveal about anti-aging research?

Ramakrishnan: The relationship between cancer and aging is complex. The same genes can have different effects over time, helping us grow when we’re young but increasing our risk of dementia and cancer when we’re older. Cancer risk increases with age because we accumulate defects in our DNA and genome, which sometimes cause gene malfunctions that lead to cancer. But many of our cellular repair systems that seem designed to protect us from cancer in our youth also cause aging later.

For example, cells can sense cracks in our DNA, which can allow chromosomes to join abnormally, which could lead to cancer. To avoid this union, a cell will either kill itself or enter a state called senescence, in which it can no longer divide. From the perspective of an organism like us, which has trillions of cells, this makes sense. Even if millions of cells are destroyed in this way, these actions protect the entire organism. But the accumulation of senescent cells is one of the reasons we age.

CNN: Has your research into the causes of death affected your lifestyle?

Ramakrishnan: Interestingly, all of the evidence-based recommendations for what can help us live long, healthy lives reflect centuries of common sense advice. We got it from our grandmothers: Don’t be gluttonous, exercise, get enough sleep, and avoid stress, which creates hormonal effects that change our metabolism and can accelerate aging.

Aging research helps us understand the profound biological implications of this advice. Eating a variety of healthy foods in moderation can prevent the dangers of obesity. Exercise helps us regenerate new mitochondria, the powerhouses of our cells that provide energy. Sleep allows our body to repair itself at a molecular level. Learning the biology behind this age-old, solid advice can encourage us to adopt a way that will lead to health and longevity.

Personally, I often say that I am well past my expiration date, but as a human being, I still feel that I am alive and have things to contribute.

CNN: What are the social costs of trying to reverse aging and death, particularly in terms of inequalities?

Ramakrishnan: Already the top 10% in both the US and the UK live more than a decade longer than the bottom 10%. Poorer people live shorter and less healthy lives.

Many very wealthy people are pouring huge sums of money into research, hoping to develop sophisticated technologies to prevent aging. If these efforts succeed, the very rich will benefit first, followed by people with very good insurance, and so on. Rich countries will likely get access before poorer countries. Thus, both within countries and globally, such developments increase inequalities.

CNN: Has exploring this topic changed your thoughts and feelings about aging and death?

Ramakrishnan: Most of us don’t want to grow old or leave this life. We don’t want to leave while the party is going on. But even as the cells in our bodies are constantly being created and dying, we continue to exist. Likewise, life on Earth will continue as people come and go. At some level, we have to accept that this is just part of the scheme of things.

I think this quest for immortality is a mirage. One hundred and fifty years ago, you could expect to live to about 40. Today, life expectancy is about 80, which, as author Steven Johnson said, is almost like adding a whole extra life. But we are still obsessed with death. I think if we lived to be 150, we’d be worried because we don’t live to be 200 or 300. It never ends.