BBC World Service podcast The Inquiry quizzed some of the world’s leading researchers about the nature of ageing – and about the cutting-edge science that could ‘cure’ it, from the role of microbiomes to 3D-printed organs.

Long tooth

What exactly is ageing? If you could zoom into the molecular level, you would see small, incremental amounts of damage that spreads to the cells, the tissue and the organs. Eventually, the whole organism starts to suffer from this ongoing Russian-doll style accumulation of damage.

“Then when we can’t keep up with the repairing, the ageing starts” explains Danish physician Kaare Christensen.

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Christensen worked as a doctor for many years until one day he decided he’d had enough of treating sick people. He now runs the Danish Aging Research Centre where he’s trying to stop people getting ill in the first place.

He points out that we’ve seen some progress. In the mid-1800s life expectancy was around 40 years in most of the world, he says, while now some countries of Northern Europe are nearing 80 years and the rest of the planet is catching up.

This was largely because of the reduction in infant and child mortality, not because the human life span itself increased. (Find out more in our recent story: Do we really live longer than our ancestors?).

Even so, there has been another, promising change at the same time.

“People arrive at higher ages in better shape now,” says Christensen. “One easy thing to observe is, for instance, teeth. You can see that the teeth of elderly people are getting better and better for every decade.”