The era of longevity: what will happen to society if more of us live past 100?

In the past five years, longevity has undoubtedly become one of the most important fields in science. People have become fascinated with the idea of turning back the arrow of time and are pouring billions into it. World-famous names such as Jeff Bezos,Sam Altman and Mohammed Bin Salman are all in on it: and it's quite possible that truly comprehensive rejuvenation — what I termed "longevity escape velocity" some 20 years ago — is now only 10, maybe 20 years away.

But what will a post- ageing world look like? When you hear about longevity from pioneers like me, we normally highlight the fact that hardly anyone will be afflicted by the health issues that currently beset the older generation. But that's not the whole story.

Many people still cling to the irrational notion that ageing is some sort of blessing in disguise; that death gives meaning to life; that longevity is a hubristic pursuit for the super-wealthy. There's no use rebutting these concerns, as my colleagues and I have been doing for years. The truth is, people are scared of getting their hopes up. The belief in the inevitability of our decline and mortality is so inculcated that it takes too big a leap of faith for people to celebrate the science that we are seeing in the lab.

There are stark economic aspects to this transition. When most of society's expectation of how long they will live suddenly mushrooms, from only a few years longer than our parents to many, many more, that will instantly translate into very different choices when it comes to big-ticket items like insurance, pensions and inheritance. These are things that dominate the global economy. Governments, pension funds and so forth would be naive to ignore this, and need to turn their attention to these matters urgently.

Let me start with a unique feature of the longevity movement, not shared by any other humanitarian effort of which I am aware. The elderly do not complain: when asked whether they approve of medical research against ageing, they'll generally respond that they've had a "good innings", and encourage us instead to focus our efforts on combatting the diseases of the young. In that sense, the elderly are the most extreme ageists among us: retirees have overwhelmingly given up on the idea that any significant breakthrough against ageing could occur in time for them. So, they rationalise away the value of such a breakthrough.

Society stratifies itself by age. It's where the whole idea of something being "age appropriate" comes from. It's why middle-aged voters tend to lean to the right and younger voters to the left. The predictability of the life course is a defining influence on how we plan our lives, what we prioritise and what we choose to enjoy: but what if that's suddenly thrown into stark relief? What kind of world will we live in once that correlation is eliminated — once progress makes a leap so big that the slow rise of life expectancy suddenly accelerates vertically — and everyone knows it?

We'll be dealing, in theory, with a world that is a whole lot wiser, because people will be able to accrue more experience over longer lives. We're still in a situation today where the elderly become increasingly limited in their ability to dispense wisdom, due to the ubiquity of processes of cognitive decline such as Alzheimer's. But supposing we could prevent — and even, to some extent, reverse — that decline. Supposing we had the advantage of much older people (120, say), whose mental agility was still at the level of a young adult, but with all the experience of an extra century of life. Imagine, with such wisdom, what we could achieve. Imagine the global issues we could solve.

You may retort, perhaps rightly, that the emergence of the internet has blunted that argument: that wisdom accruing with age is dependent on there being wisdom in the first place. It's unclear how far the internet has affected our cognitive abilities, but many believe it is the reason for a general intellectual decline. I think there needs to be more research done into this — but for now, let's move on to an aspect of social interaction that does not, as far as I can see, yield to such logic: entertainment.

Think of how we qualify music genres by reference to age groups. The same goes for the medium through which we choose to tell stories: books, film, television, video games, even virtual reality. We stratify and typecast our modes of interaction (Facebook is for Gen Xers, Instagram is for millennials), even though the reality is already more fluid. It is not uncommon to see a crowd at, say, Glastonbury where generations will blur as they sway to the music of Coldplay. But we're not yet at a stage where you could plausibly ask your grandparents if they know what Brat summer is and expect them to know what the hell you're talking about. I imagine, in a post-ageing world, your grandparents will have no trouble knowing all about Charli XCX. And, what's more, dancing to her songs with you.

We talk at length about what rejuvenation means for the body, but we must not forget that it's one with the mind. The elderly are less inclined to explore new things as time passes — to explore novelty and get the most out of life. In 10 to 20 years, all that will change. We'd best prepare ourselves for what that means.