Population Growth : Bane or Boon ?

Is growth in the population of a country a bane or a boon to the economy ?
It was thought that large increases in population would increase demand to such an extent that it would outstrip supply and this would result in economic hardship. ( Malthusian catastrophe http://en.wikipedia.org/wiki/Malthusian_catastrophe)
In the 1960 s and 1970s countries like India and China made great efforts to try and control their populations believing that this was one of their major problems.
However , with economic liberalisation , their economies have begun to grow at an exponential rate and now they find that their large populations are a great attraction to foreign investors in view of the large market for goods that this presents .
In contrast in Western Europe where populations have remained static or shrunk , the economies appear to be in decline . Most european manufacturers in particular and service indutries as well are looking to establish in China and India to take advantage of these huge developing markets .
The bottom line appears to be an increase in population is a boon rather than a bane to the economy.