Going grey

The end is in sight for the world’s population explosion. A report in this
week’s Nature(vol 412, p 543) welcomes new predictions that the number
of people on Earth will decline after peaking in around 2070. However, it warns
that nations will struggle with social and economic challenges because the ratio
of elderly to young people will rise dramatically. In Japan, for instance, half
the population is likely to be 60 or over by the end of the century.