Study Fig. 1.1, information about population growth in China. China introduced a one-child policy in 1979 to stop over-population. Now China is worried about under-population. In the 1970s, the Chinese government was worried about how fast its population was growing. More people need more food, more homes and more jobs, and population growth can also damage the natural environment. It was believed that this would create problems, so the government decided to introduce the one-child policy. China kept the policy. However, in 2013, all married couples were permitted to have up to two children and recently this was increased to three. One of the reasons for these changes was that China is now worried about under-population. A society that has fewer children becomes a society that has fewer working adults. That means fewer people making things to sell, fewer people growing food, fewer people paying taxes, fewer people to support older family members and fewer people to join a country's armed forces.