THERE IS A DEMOGRAPHIC DIVIDEND TO BE ENJOYED.

spending as long in retirement as in work. We will have to radically change our thinking about the typical three-stage life of childhood and education, work and then retirement.

A multi-stage life, during which we will move in and out of different careers, retraining as necessary, sometimes earning more and sometimes less, will become the norm. Our grandchildren’s lives could look very different, and potentially much more exciting, than our own.

For investors, this creates numerous opportunities. Aging populations mean an increased need for medical services, care and treatment. The current crisis in the U.K.’s National Health Service is a product “dependency” ratio begins to rise after more than 40 years of falls. This is the figure that compares the number of non-working-age people relative to those who are still in the workforce, generally regarded as being between 15 and 64.

The dependency ratio is currently 54 per cent, according to the World Bank, and it has been falling since 1970. That is because the workforce has been growing more quickly than the number of older people it needs to support. But from this year that will no longer be the case. The reason is simple. We have been living through a golden period between the moment when medical advances reduce mortality rates and the subsequent point when social change and economics cause the birthrate to drop. First we stop dropping like flies, then we stop breeding like rabbits.

In time, that shift will cause a demographic deficit. But before that happens there is a demographic dividend to be enjoyed. Global population growth is expected to support a significant rise in consumption around the world. The World Bank predicts a 50-percent rise in the demand for food by 2030, for example. That will lead to shortages of water, arable land and energy as industrialization and urbanization take place. Companies that can help provide a solution to those problems will be multiyear growth stories. Ecolab is one: a provider of water sanitization and energy-efficiency products, 90 per cent of its sales are recurring, it enjoys high margins and has low capital requirements. It has scale in a fragmented market and is developing innovative products. It is a buy-and-hold investment powered by demographic change.

The third key demographic theme is the ongoing expansion of the global middle class. As with the other demographic certainties, growing affluence in emerging markets is a doubleedged sword. More disposable income, in some cases the first time a family has enjoyed the ability to spend above a subsistence level, is transformational. Greater numbers of people travelling, more e-commerce, an explosion in sales of white goods, are all positive opportunities.

Stocks such as Shanghai Airport and the online retailer Inditex are beneficiaries of these trends. But even the negatives, such as obesity and lifestyle- related diseases, can be good news for investors. The French firm Essilor, the world’s largest manufacturer of ophthalmic lenses, has succeeded on the back of rapid growth in demand for corrective lenses, and the trading up seen in emerging markets to higher-quality glasses. Death and taxes we will have to put up with, but demographics is one certainty we can learn to love.