People love to panic. The millennium bug, SARS, HN51, the apocalypse, asteroids, GM food, grey goo – you name it and someone somewhere is chomping down on their fingernails just thinking about it.

But if there is one thing that people love to panic about, it’s overpopulation. From a certain point of view it’s easy to see why. If you look at a historic map of the world’s population it looks like a tidal wave, sweeping up from 1.6 billion people in 1900 to 6.7 billion in 2008. According to Wikipedia, the world’s population is forecast to be 9.7 billion in 2050.

A lot of people tend to look and these figures and get hysterical. I’ve seen plenty of internet comments and blogs from distraught netizens who make unsubstantiated comments such as the world’s ‘ideal’ population should be around 1 billion.

I’ve yet to see a single workable solution to reduce the population to this kind of level. Sure, you can enforce a one or two child limit if you are prepared to accept enforced abortions or potentially massive gender biases due to selective abortions. However, this only reduces the population in the long term. In the meantime you are literally waiting for billions of people to die.

This kind of hysteria has a long tradition. In 1798, the economist Thomas Robert Malthus published the first of his treatise on overpopulation. Malthus hypothesised that since humans reproduce geometrically (i.e. at an increasing rate) whilst food production increases only arithmetically (i.e. at a steady rate) then the natural result would be overpopulation and subsequent mass starvation.

Luckily for us Malthus basic assumption was flawed. Advances in technology made geometric increases in food production possible. Moreover, such advances continue to be made in the form of GM foods and new farming methods which allow for more and more land to be brought under cultivation.

We currently produce enough food to feed the world 3 times over. Even if no extra advances in agricultural technology were made this means that we could feed a population of over 19 billion people, assuming as well that no extra land was brought under cultivation. Even the most pessimistic neo-malthusians do not predict this kind of population increase.

If this is the case, why do we have famines and starvation? This is a reasonable question. In his classic 1982 book ‘Poverty and Famines’, Nobel Prize-winning economist Amartya Sen postulated that famines happen because of a lack of purchasing power, not because of a lack of food. He showed that in many famine situations food supply was not affected, but instead starvation occurred because poor farmers who lost their crops could not afford to buy food.

In the same way, poor individuals in poor countries are often unable to purchase food because they cannot make enough money to do so, not because there is not enough food. When the world’s food supply is hit by a shock that sends prices up, many of these poorest people simply don’t have enough money to purchase food, with awful results.

Sen also showed that famines do not occur in democracies, because political pressure forces governments to act. In doing so, he illuminated one of the key dimensions of this debate. In contrast to Malthus predictions, as populations get richer and, crucially, as women become better educated, the population decreases rather than increases.

This is one of the reasons that population growth has actually begun to decelerate. In the western world, some countries actually now have to worry about population decline rather than population growth. Even in developing countries the fertility rate has declined drastically due to economic development and greater education provision for women. In Iran the fertility rate has dropped from 7 in 1984 to 1.9 today. All of this makes it more important that rich countries continue to support economic and political development in the rest of the world.

The most dedicated of neo-malthusians also point to the other problem of overpopulation, the use of resources. While it is difficult to deny that this is an issue, especially in terms of overfishing, pollution and deforestation, it is clear that each of these problems is forcing a response from even the least responsible of nations.

Green energy technology has received a massive boost in investment due to the climate change worries. If this can be perfected over time it offers the promise of cheap and clean electricity. Likewise, new and innovative initiatives are being found to combat the problems of overfishing and deforestation.

There’s no way I can argue that there are no problems facing the world, but the fact is that humans have been able to respond to the challenges of increasing population with technological solutions for at least one hundred years now. There is no reason to think that this will change in an era of accelerating technological progress.

The fact is that in modern democracies the problem is not one of starvation but obesity, overabundance rather than famine. True to form, people have begun to panic about this as well. While the true effect of population growth can only be seen over time, in the meantime we can at least be sure of one thing, that there will be more and more people around to worry about overpopulation!