“Some people predict humans will become immortal - I don’t believe that, but certainly it’s feasible for us to live for a very very long time,” says science author Mun Keat Looi.
Drugs in mouse trials have already proven it’s possible to extend life - albeit with certain drawbacks - and other discoveries could extend it further, he says.
“There is a hint that each animal has within it the abilitiy to live much longer than normal,” Looi writes.“If you can stay alive for, say, 20 years, until the next medical advance arrives, you could imagine keeping going for another 20 years, and then another.”
Looi says that some believe that eventually, scientific advances will arrive so rapidly, that they will “keep up” with the ageing process - making us live forever.
Looi features some of these experiments, alongside more radical thinkers in an essay “Will we ever be immortal?” in The Big Questions in Science.
Scientists are already closer to understanding the ageing process - and perhaps finding a drug that can “treat” what one scientist describes as “the grim reaper gene.”
“We’re coming to see ageing not as a fact of life, but as a disease we might be able to treat,” says Looi - pointing to treatments which “fool” the body into thinking it’s under threat, so that cells “maintain” themselves.
“Cynthia Kenyon at University of California, San Francisco is well known for her work on the genes involved in metabolism and ageing,” says Looi.
Kenyon doubled the lifespan of a worm by breeding mutants, looking for ones that lived longer - her assistant walked into her office after inspecting one mutant strain and said, “Guess what? They’re not dying.”
Kenyon dubbbed the gene “the grim reaper” - as its function is to stop animals from staying young. Some long-lived human populations, such as Ashkenazi Jews, have mutations that impair the gene.
“There are some far out people who believe that we may extend human life very soon,” says Looi.
“Between 1979 and 2010, average life expectancy worldwide rose by 11 years for men and 12 years for women - 2.5 years every decade.”
“Aubrey de Grey of the SENS Foundation (whose background is actually in computer science) is famous for saying that ‘the first person to live to 1000 years old is about 60 now’. But most scientists think that’s rather too bold.”
“Life expectancy is growing by two years per decade at the moment,” says de Grey, whose belief is that scientific advances will eventually come so quickly that human lives will extend for hundreds of years. “But it will be one year per year”.
Other research is already throwing light on a potential focus for research - and experiments in mice have shown that it is possible to genetically modify animals to live longer.
“On the more reasonable side of things, we have many brilliant scientists working on different aspects of ageing around the world,” Looi says.
“Elizabeth Blackburn and Jack W Szostak won the Nobel Prize in 2009 for their discovery of telomeres, 'the plastic caps at the end of the shoelaces’ that are our chromosomes and that shorten as we age,” says Looi.
By shortening “telomeres”, human cells could be made to age prematurely.
The discovery won the Nobel Prize. Subsequent research has shown that mice live longer if they are genetically modified to have longer telomeres.
But the research is still at an early stage - and although clinics now offer tests which “predict” when you will die, our understanding of the process is still at an early stage.
Other scientists are looking for less invasive methods to combat ageing. One theory suggests that a highly restricted diet may increase lifespan.
“There has been evidence for some time that calorie restriction may also reduce the rate of ageing, with some spectacular results in extending life in nematode worms and mice, but mixed results in apes,” Looi says.
“Studies are ongoing in humans - obviously they take longer and are harder to conduct. In the meantime, scientists are studying the genes and processes that link metabolism and ageing, which may lead to some drug interventions. But that’s still quite a way away.”
But drugs may also offer an “answer”, Looi says.
“Drugs are a good bet - we already have some drugs that seem to extend life in mice (sadly they also tend to dampen down the immune system, so not quite right for human use!).”
“The more we understand what ageing is and what causes it, the more we see that many diseases - type 2 diabetes, cancer, osteoporosis, cardiovascular disease - are actually disease of ageing, so treating the root cause may help us combat many diseases at once.
“Here in the UK we have some brilliant ageing scientists such as David Gems and Matt Piper of UCL and Tom Kirkwood at the University of Newcastle, the latter one of the leading thinkers in ageing.
"Building on many earlier theories, he’s suggested ageing might be the result of the body having a limited amount of energy and must choose how to spend it - maintaining a body or reproducing. And reproducing, at least for the moment, is the more viable long-term option for ensuring the longevity of your genes.”
Looi says the idea that we could understand ageing, invent therapies, and live forever “doesn’t mean we would be immortal - there’s always the possibility of disease or accident getting us.”
“And living long doesn’t mean living well,” Looi warns. “The growing ageing population is a major issue for the globe - the WHO reckons there’ll be 2 billion people over 60 in the world by 2050.
As David Gems has said, "People aren’t afraid of dying. Theyre’re afraid of having to have someone else take them to the toilet".