Let's put it another way. The core of the debate is about the so-called demographic dividend, which occurs when falling fertility lowers child dependency, and when the working age population (aged 15-64) expands, but before old age dependency starts to rise significantly. This dividend is associated with rising investment and accelerating economic growth, and describes the situation that western economies have enjoyed for the last 30 years or so. But they have now exhausted this benefit, because weak fertility is keeping the supply of new workers in check, while the long-living boomers are going to be increasingly visible, bringing to their children hefty bills for income support and care costs. Consumption patterns will change, brands and spontaneous purchases will give way to more regular and common-or-garden consumption, and aggregate savings will decline over time. While the boomers may delay the asset switch equities could fall well short.

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Emerging market demographics, as I have suggested, are, for the most part, strongly supportive of the demographic dividend. Even in China, the pool of rural migrants should serve as an offset to the fall in the working age population for a little while longer. It is in emerging markets, with massive demand for infrastructure and capital, where returns will be the greatest, even barring the odd bubble and bust now and then. It would certainly help relatively poor countries, with weak social security systems, to learn from the experience of the rich world what works and what doesn't in dealing with destiny.

Eoin Treacy's view Demographics, if anything, is a thorny issue and it is dangerous to draw radical conclusions from what one might see in apparently simple to understand data. However, the demographic dividend is a well-publicised factor in economic growth. The world's large population centres are moving into a sweet spot in terms of their demographic structure. This is not enough on its own to supply outsized investment returns but when improving standards of corporate, economic and civil governance occur in tandem with this macro condition then the potential for truly impressive investment returns exist. No one knows whether deflation or inflation will triumph over the medium to long term in some of the more indebted countries but what seems clear is that other areas will do considerably better from an investment perspective.