Andrew Steele is a Briton based in Berlin. At Oxford University he gained a PhD in physics, but then he switched to computational biology, and held positions at Cancer Research UK and the Francis Crick Institute. Along the way, he decided that aging was the single most important scientific challenge of our time. This led him to write the book “Ageless: The New Science of Getting Older Without Getting Old”.
Steele has become one of TV’s favourite science experts, appearing on the “Impossible Engineering” show on the Discovery channel, and the “Strangest Things” show on Sky. He joined the London Futurists Podcast to discuss the fast-moving science of longevity.
Your risk of death doubles every eight years
Steele joined the longevity community because of a single graph. It shows how likely you are to die at any given age given that your risk of death doubles every eight years. In your mid-30s, your chance of dying during a year is one in 1,000. By the time you reach your mid-60s that risk has increased to one in 100, and in your mid-90s it is one in six – the roll of a dice.
This eight-year doubling is constant around the world and across time. This is surprising, because mortality rates were much higher before the industrial revolution, and they are uneven around the world – and between income groups – today. The explanation is twofold. First, fewer people survived into adulthood before the twentieth century, and second, the background mortality rate varies across time and geography. So one in 1,000 is the number for a 35 year-old today, but it would have been worse before 1900.
This exponential curve of increased mortality is known as the Gompertz Curve, but there are animals which don’t obey it. A tortoise, for instance, is “negligibly senescent”, which means it enjoys something called biological immortality: it does not age. It does not die of old age, or the diseases of age, and it remains sprightly throughout its life – or at least, as sprightly as a tortoise can be. A Galapagos tortoise called Harriet died in 2007 at the grand old age of 175. Of course there are also animals which have shorter lifespans: a mouse’s chance of dying doubles every few months.
Hallmarks of aging
There are many approaches to slowing down and reversing the aging process. Steele talks of ten hallmarks of the aging process. Aubrey de Grey, famously, talks about seven causes of aging, and other people talk of nine, or twelve hallmarks, or pillars. Steele says these are essentially different ways of cutting the same cake.
There is a debate in longevity circles between those who think we age because of wear and tear, and those who think that aging is programmed into us by evolution. Steele thinks there is a bit of both. The unfortunately named phenomenon of “antagonistic pleiotropy” means that genes can have good effects early in an animal’s life, and deleterious effects later on. Animals want to live as long as possible, and they also want to have as many offspring as possible that survive long enough to reproduce themselves. Evolution is really only interested in the latter. A mouse is small and vulnerable to predators, so evolution has selected mice which reproduce a lot while young, rather than mice which survive a long time. A whale is big, and has no predators apart from humans, so evolution selects whales which live long enough to raise calves to maturity.
Programmers versus engineers
People in the programmed aging camp often look for ways to change the programming, using genetic therapies, for instance. People in the wear and tear camp often prefer engineering solutions, and argue that trying to re-programme the body may lead to unforeseen side effects. Steele is sympathetic to both camps, and argues that it is not always easy to tell the difference.
For instance, one therapy which does slow the aging process in animals is calorie restriction. This does not just mean animals cutting down a bit on carbs, but consuming as little as 40% of what they would normally eat, while getting all the nutrients necessary for survival. Many people argue this is cutting down on wear and tear, but it can also be seen as a metabolism intervention that changes how the body works. (Sadly, calorie restriction this severe is hard for humans to tolerate, but there are hopes that therapies based on a drug called rapamycin may simulate it.)
Human biology is fearsomely complicated, and Steele thinks that when we crack longevity, and develop a cocktail of therapies which postpone and reverse aging – a different cocktail for each of us, probably – they will not fit neatly into a model which can be understood by un-augmented humans.
He argues that we need to address all the hallmarks of aging at the same time, but other researchers think there may be silver bullets, and we should focus on them. For instance Bill Andrews thinks that repairing telomeres is a silver bullet. (Telomeres are like the plastic end caps on shoelaces, and they prevent damage to our chromosomes as they divide.) Another researcher, David Sinclair, thinks that reversing damage to our epigenome could help with many of the hallmarks, and his approach seems to be the one adopted by Altos Labs, which is richly funded by Amazon founder Jeff Bezos among others.
We could be just $100bn away from curing aging
Aubrey de Grey now thinks that longevity escape velocity – the moment when science gives us an extra year of life every year that passes – is possible in fifteen years or so. Steele replies that we should measure the distance to that milestone in research dollars rather than in years. There is plenty of money going into senolytics, which is ridding the body of moribund cells, but most of the hallmarks of aging are still not being properly addressed. And in each case, the amount of money needed is in the tens of $billions, not the hundreds. So overall, we may only be $100 billion away from longevity escape velocity. This is a mere $100 for each person in the developed world.
Every time Steele gives a talk on longevity science, somebody asks whether the result would be over-population, and unsustainable demands being put on global resources which are already under strain.
The UN forecasts the human population at 9.8 billion in 2050, up from 8 billion today. Even if it was possible to completely cure aging by 2025, and successfully roll out the cure to everyone in the world, then the population in 2050 would go from 9.8bn to 11.3bn. This is a 16% increase, which is not nothing, but by 2050 it is a racing certainty that we will have improved the efficiency of our production processes by far more than 16%.
“Be more tortoise”
Aging is the biggest single cause of mortality today, causing more than 100,000 of the 150,000 deaths which happen globally every day. And deaths from aging are not gentle. Their proximate causes are cancer, heart disease, and dementia, which often take years, and inflict terrible pain and suffering on the patient, and their family and friends. It is both important and urgent that we work out how to “be more tortoise”.