South Korea, however, has an extremely closed immigration system and only recently has there has been a growing consensus that at least some adjustment to the strict laws are needed. As of June 2013, the number of people without Korean citizenship staying in the country for three months or longer amounted to just a little less than 3 per cent of the total population. According to one 2008 study , nearly half of South Korea's population had never even spoken to a foreigner.

Low birth rates don't have to be synonymous with a population decrease. Countries such as the United States, for example, have been able to counteract their low fertility rates with immigration. Germany, which has one of the lowest fertility rates in the world, is increasingly attracting foreigners from all over Europe.

A fertility rate measures how many children a woman bears on average. While the world's average number is estimated between 2.33 and 2.50, a ratio of 2.1 is necessary for a population to maintain its population levels. However, some East Asian countries as well as many other developed nations (for example France, the United States or Sweden) suffer from low birth rates.

Of course, that wouldn't be such a problem if fertility rates were higher. So why are they so low? Thomas Anderson, a demographics researcher at the University of Pennsylvania, thinks that East Asia's low birth rates are related to "social and economic barriers." In a study published last year, Anderson argues that "couples in East Asia are more likely than their Western counterparts to have just one child in order to invest heavily in that child's human capital." Essentially, parents would prefer one successful child over a number of low-achieving children.

Other factors also play into the decision on whether to raise children or not. According to Minja Kim Choe, a senior research fellow at the East-West Centre, "the view that 'it is necessary to have children' has declined substantially." Choe explains that an "increasing proportion of women will be evaluating costs and benefits of having children" and compare it to alternative options such as spending more time on work or hobbies.

South Korea's problem hasn't come out of nowhere – a gradual societal transformation has taken place. A chart, above, included in a paper by the Korea Economic Institute shows how things have changed over time.

The South Korean government has tried to respond to this shift by pursuing policies such as a more attractive maternity leave and subsidies for childbearing. In 2008, the South Korean government spent $US3.8 billion ($4.07 billion) on programs to increase the birthrate. The Korea Economic Institute's Elizabeth Hervey Stephen examined the effect the money had four years later and came to the conclusion that "to date, the policies have not been effective, which in large part is due to the country's work culture and gendered society."

Of course, South Korea has more than 700 years to reverse this trend, so take the 2750 time line with a pinch of salt – even if this research's findings are accurate, many factors are likely to change a lot during that time frame. In the meantime, South Koreans can take solace in their pets: In 2013 the Wall Street Journal reported that total private expenditure on pet supplies had annually increased by more than 14 per cent since 2000, despite their demographic woes.