We could radically extend the human lifespan. Heres why we shouldnt – BBC Science Focus Magazine

In 2020, US and Chinese scientists found a way to enable nematode worms to live five times longer than normal by manipulating their genes. Worms are often used in ageing research since weve inherited some of the same genetic circuitry during evolution. Its suggested that targeting some of these conserved genes using drugs could be a way to extend the human lifespan.

But since worms only live for a few weeks, extrapolating the US and Chinese scientists success to humans could be foolhardy. In short, we cant expect to live to 500.

But lets not be greedy. We already live far longer than our hunter-gatherer ancestors, who invariably snuffed it before the age of 40. Should we, though, stop considering life as something that comes to its natural conclusion at 73 (todays average global life expectancy) and devote more of our time to curing old age?

One argument against extending human life beyond the norm is that it would lead to overpopulation, requiring more resources, while creating more waste, carbon emissions and pollution on a planet weve already stressed to breaking point.

Thats not usually what happens when people start living longer, though. Instead, birth rates tend to drop as people have fewer children and have them later in life. We know this because its already been happening for several decades as healthcare has improved.

So even though the global population is growing, its not growing as fast as it once was and in many richer countries, across Europe for example, populations are plateauing or shrinking as the birth rate (the average number of children each woman has) drops below two. The worlds longest-lived nation, Japan, has an average life expectancy of 84 and a birth rate close to one, down from over two in the 1960s when life expectancy was below 70.

So provided people had fewer children, perhaps we could all live a little bit longer maybe as long as people in Japan. In fact, some of todays four-year-olds can already expect a much better innings. In the UK, around a third are predicted to see their 100th birthday due to a trend towards living longer.

Whether those extra years are desirable is another matter though, given theres no indication they would be healthy ones studies from countries where life expectancy has increased have shown mixed results.

Meanwhile, the gulf between life expectancy in richer and poorer countries leads us to suspect that life-extending drugs and technologies will take longer to reach the less-developed nations.

Today, people in some African countries die on average two or three decades before the Japanese. So given the disparities that already exist, is it ethical to have more people living longer in richer countries, where we consume more resources?

If we were going to be fair about it, our first aim should be to increase life expectancy in Africa and the rest of the less-developed parts of the world, and ensure that a longer life doesnt come at the expense of healthy, happy life, right up to the end.

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We could radically extend the human lifespan. Heres why we shouldnt - BBC Science Focus Magazine