Gerontology: How long will you live?
By Frederic Friedel
Recently I was having lunch with Nigel, whom I have known since his early teens. Our conversation drifted to health and life expectancy, and Nigel said he would probably live to maybe 75. I corrected him: he could, in my view, reasonably expect to hit 87. “What about you?” he wanted to know. “For me I think 92 is a reasonable estimate.”
Nigel found this somewhat difficult to accept: “We are both in fairly good health, and I am twenty years younger! How come you can expect to live longer than me?” I explained it to him — but you might want to take a minute to find the relatively simple reason. The answer is given below the next passage. Why could I reasonably expect to live longer than Nigel, reach a higher age than he?
Humans have existed in their current form for between 100,000 and 200,000 years. What I mean by that is that if you could transport an infant from 50 or 100 thousand years ago into our current time, this child could expect to live for over 70 years, like everyone else, and he or she could also go through school and college without much difficulty.
The world average life expectancy is currently just over 70 years, and differs for different countries.
The average life expectancy varies greatly depending on the region of the world in which you live — it is around 50 years in Swaziland, 80.7 years in Europe and 83 years in Japan (for infants born in 2015). But it also depends on the age in which you live. Here is an overview:
- The average life expectancy of our shared great ape ancestors, around five to seven million years ago, was probably around 15 years.
- The first homo species around two million years ago had an average life expectancy of around twenty years.
- Homo sapiens, around 100,000 years ago: 30–35 years. Encyclopædia Britannica sets the life expectancy in the Palaeolithic age at 33; the Neolithic at 20–33; the Bronze and Iron ages at 26.
- In Classical Greece the average life expectancy was 25, in Classical Rome it was 20–30, the same as in Pre-Columbian America.
- In late medieval English life expectancy was 30, in early modern England 33–40.
- At the turn of the 20th Century the world average was 31, by 1950 it had climbed to 48, and in 2014 it had reached 71.5.
In the above we are talking about life expectancy at birth or in early infancy. When a child was born, in Mozart’s day, it had a life expectancy of 22. Around 40% of all infants did not make it to the age of one. A five-year-old could expect to live to the ripe age of 33. And that was actually the case, in real life. If you read diaries from the time you find passages that go something like this: “Little Annegret died last night. We are all so sad — she was such a beautiful girl. This morning I finished the second movement of my piano concerto, which is coming along very well…”
Death was a common experience: Johann Sebastian Bach fathered twenty children — only ten survived to adulthood, and none of the last three lived a full year. Bach himself lived to 65, Mozart died when he was 35. And Franz Schubert, who left us over six hundred Lieder, seven symphonies, sacral music, operas, chamber and piano music, only made it to the age of 31.
Now back to the question of why I could reasonably expect to live longer than Nigel, who is considerably younger? Well, precisely because I am older than him: I have survived the twenty years that lie between us without serious mishaps: no fatal accident, no hideous diagnosis of some terminal illness. He has to get through that period unscathed, after which his life expectancy will rise to my level — or rather clearly exceed it, thanks to medical advances that are coming in the next two decades. To make it perfectly clear: if a frail centenarian — a 100 year old person — were present at our luncheon meeting, I would have predicted a life expectancy of 105, maybe, much more than for myself or Nigel. For the same reason.
The next question to Nigel, and a number of friends had joined us at our lunch table, was: how long could my grandson Hennes, a three-year-old super charmer, hope to live? I was more precise: I was not asking how long a German three-year-old could expect to live on average, but how long he could live if everything goes perfectly for him (no accident, no fatal disease, optimum medical care). People started to guess, and you can think about it yourself, while I take a closer look at ageing and maximum life expectancy.
I need to stress: the subject now is not the average age human beings statistically attain, which as shown above has varied tremendously throughout history. It is the maximum age they can achieve, under extraordinary circumstance. That has not changed significantly over the last 100,000 years. Individuals of the species neanderthalensis, floresiensis, denisova, and currently sapiens all had the same maximum age limit — we are biologically limited to reaching around 100 years under optimum conditions, with exceptional cases making it to about 120. The oldest properly verified record was Jeanne Calment, a French lady who was born before the Eiffel Tower was built and actually met Vincent van Gogh. Calment died a decade ago, at the age of 122 years (do me a favour: ignore stories about 120+ individuals who enjoy great health, and even run marathons — usually they have taken on the identity of a parent and are clearly in their 70s or 80s). The average age in a population is so much less than the maximum age because of disease, adversity, accidents, warfare, etc. But certain individuals have reached 100 in almost all nations and at all times, even 100,000 years ago.
So we are exactly where our neolithic ancestors were — no extension to the maximum age: people now live into their 70s or 80s, on average; but no humans exceed 122 years, or ever have. So the correct answer to how long a three-year-old could expect to live, under ideal circumstances, was until a few decades ago, around 120 years.
But the answer I sought during the luncheon meeting with Nigel was posed in the second decade of the 21st century. The answers I got were 100, 120, 130 — nobody came close to what I had in mind. Except the CEO of an Internet gaming startup, Kate, who I firmly believe is a clone of Nicole Kidman. Kate nonchalantly gave me the correct answer — or let us say the answer I wanted: one thousand years. This had the other guests cringing, and I had to promise them to write it up, explain why I was not simply pulling a crazy number out of a hat. Which is what I am now doing (writing it up).
But first a question to Kate: how did you come up with 1000? “I probably read the same articles and watched the same lectures as you, Frederic.” She had been following the progress being made by Aubrey de Grey at his SENS Research Foundation, the Google biotech company Calico, and other such research and development companies that are working on the problem of ageing and associated diseases. I will be describing the research and results in a future article, in greater detail — here for now is a short summary and some links to lectures and papers.
Aubrey de Grey, 53, is a remarkable person, a conspicuously hirsute English gerontologist working on the problem of ageing. He inherited a small fortune from his mother, used part of it to buy a modest estate in the mountains near the Google town of Mountain View (the Financial Times says it is “exactly like the place you would expect a mad professor to live”). The bulk of his fortune, however, was invested in the SENS Foundation. In recent times de Grey has gained a certain degree of notoriety by claiming that there are human beings alive today who will live to 1000 years — or in fact indefinitely. In the video lecture I give below he explains why this claim often causes public consternation, and how it is not as outlandish as it sounds.
Ageing, according to de Grey, is basically a technical problem. It is simply the life-long accumulation of damage to the tissues, cells and molecules of the body. This is initially harmless, since the body has extensive repair and replacement mechanisms. But ageing eventually overtakes them and ultimately the ageing individual succumbs to a disease that would be survivable in someone much younger. However: we are now within reasonable distance of developing treatments that bring ageing under the same level of medical control that we have today for most infectious diseases.
There are two traditional approaches to combating a disease. One is to try to cure diseases when people get them, and the other is to try to prevent people from getting them in the first place. For the diseases of old age, however, there is a third approach: identify what the difference is between a young person and an old person, and then try to eliminate the difference before it can cause the diseases.
The de Grey approach says: let’s not try to slow down the process where metabolism causes damage, and where damage leads to the pathology — diseases and disabilities. Instead let’s uncouple those two processes by periodically diving in and repairing the damage when it is still sub-pathogenic. He classifies the damage the body does to itself during ageing into seven distinct categories (that have been known for decades) and summarizes the medical strategy to combat them in four Rs: repair, remove, replace, reinforce, i.e. restore the body to a state where it can naturally deal with the diseases. For details on this go to 12 min 14s in the video lecture below.
Should this research succeed, and it certainly looks promising, we will see some of the diseases of old age finally reduced, and the average lifespan will increase. And of course the time this buys us will allow for more development, which leads to what is called “Longevity Escape Velocity”, the point where we gain more than one year of average lifespan per year. Then differences between young and old will fade away.
But this would not lead to eternal life. Even if death from all diseases, including those of old age, is eliminated, we could still be hit by a bus. Given our current rates of accidents, we can estimate a maximum life expectancy for an infant in 2017 of somewhere around 1000 years.
Think this is all a pipe dream, unsubstantiated fringe enthusiasm? A few months after my discussion with Nigel and the others, Der Spiegel, the most influential news magazine in Europe, devoted a cover story to exactly what I was contending. It is entitled “Immortal Life, soon for everybody! How humans will overcome death.” And of course the article was devoted to the work being done by Aubrey de Grey and by other similar companies and scientists. Were the Spiegel people listening in on our discussion?
Why is this research so important? Let us look at some statistics: ageing kills 100,000 people a day, the world over, twice as many as all other causes of death combined. In the industrialized world it is the cause of 90% of all deaths — and at the same time at least 80% of all medical expenditure goes to diseases of old age. The US governmental National Institute of Health spends roughly 30 billion dollars a year on medical research, but only 3% of that (roughly one billion dollars) goes to the National Institute of Ageing — and only one sixth of that billion is spent on actually trying to do something to combat ageing (the rest is spent on things like improving the dignity of growing old). The total amount spent by the government on understanding ageing is not much greater than that spent by the SENS Foundation on the same enterprise.
I cannot resist one final note: when discussing the subject with my son Martin, he said: “You realize that Mark Zuckerberg will not die!?” How so? Well, he is immensely rich and at the same time young and healthy. Unlike Bill Gates or Warren Buffet. True, Mark, who is 33, has a fair chance at immortality — Google founders Sergey Brin and Larry Page, both 44, are also on the bandwagon, and Peter Thiel, 50, billionaire co-founder of PayPal and Palantir, is explicitly on a mission to cheat death. Our reaction can only be: good luck to you guys, or take me with you, please!
Addendum [August 2021]: I had an interesting discussion with a friend who has recently become a grandfather. We speculated why there were so many more old people than in previous time, why average age expectancy had risen so dramatically. Clearly lifestyle, medical care and treatment, etc. play the greatest role. But had there been any evolutionary pressure in play. Clearly keeping individuals of the species alive for an unnecessarily long time (twenty years would be enough for vigorous procreation) was to provide child-bearing individuals care and guidance; and of course, this becomes a factor in selection. Individuals that reach an older age can better help with the survival of the progeny that carry their genes. So there is more chance that such individuals will pass them on, and their numbers will increase. Interesting thought.