This article originally appeared on the BBC World Service.

For the first time in history, there are more elderly people in the world than young children, according to the United Nations.

Their figures show that the number of over-65s surpassed that of under-fives at the end of 2018.

There are now around 705 million people over-65 on the planet, while those aged 0-4 number about 680 million.

Widening gap

Current trends point to a growing disparity between the oldest and the youngest by 2050 – there will be more than two over-65s for each person aged 0-4.

This widening gap symbolises a trend that demographers have been tracking for decades: in most countries we are all living longer and not making enough babies.

But how will this affect you? Could it already be doing so?

Not enough ‘arrivals’

Christopher Murray, director of the Institute for Health Metrics and Evaluation at the University of Washington, says: "There will be very few children and lots of people over the age of 65 and that makes it very difficult to sustain global society."