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Why and how are we living longer?

What is the topic of this review? The reasons for the continuing increase in human life expectancy are examined in the light of progress in understanding the physiological basis of ageing. Prospects for further extending the health span – the period free of age‐related disability and disease – are critically assessed. What advances does it highlight? No active programming directly causes ageing, which instead results as a side effect of how evolution optimises the physiological allocation of resources between growth, reproduction and maintenance. Under pressure of natural selection, there was insufficient priority in maintaining the body well enough that it could endure without progressive accumulation of multiple kinds of molecular and cellular damage.