Every so often a general panic seems to arise over population growth. The general pattern seems to be a bunch of rich people complaining that the poor are breeding so much that it won't be possible to feed them. The rich people generally seem to assume that the resulting famine will not apply to them, specifically, but general disaster will happen 'somewhere out there'. The name most associated with these visions of disaster is Malthus, Reverend Thomas Robert Malthus, who, in 1798, published his Essay on the Principles of Population¹. The essay was a response to "Mr. Godwin² and Mr. Condorcet³". These two gentlemen were proposing utopias that Malthus thought went too far. He particularly disagreed with the idea that mankind could somehow progress and improve, so he set out an opposing position.

Malthus took two simple ideas as his basis. First, people are naturally inclined to procreate and this inclination will increase population in a "geometrical ratio". Second, development of food supplies can only ever increase linearly. Thus population will outrun food and disaster will result. Now, it is mostly the poor that reproduce in this profligate way, and charity and other such helpful things would only encourage them, so the conclusion is that population must be controlled. Malthus also added moral position to his calculations: if you can't earn a living you don't deserve one. Since excess population implies unemployment the death by starvation of the burdensome horde would be morally as well as arithmetically justified.

The argument sets out an extreme position based on assumptions that could have been questioned at the time. It turns out, though, that the world has just enough people who chose not to look too closely. Pearce lists enough of these to make the horrifying point: from the approach to the Irish famine of the 1840s, through to Indira Ghandi's mass sterilisations, via eugenics movements of all descriptions. Malthus has created a base that allows politicians to be lazy and white men to be supremacist. Along the way he notes that the green revolution was not all it was cracked up to be. This was a supposed to be a fix for food shortages, largely in response to warnings of overpopulation. The result was indeed an improvement in yields, but the long term collateral damage has been disastrous. Pearce's conclusion from all of this is that many of the disasters, famine, genocide, that are attributed to population are in fact political, ranging from reluctance to offend a powerful group through to deliberate attacks on a threatening sub-group of a population.

From this starting point, Pearce notes that population can, in principle, be an issue. In a closed system it is quite easy to see that there is going to be some number of people that is more than the available food supply can support, and it is worth the political effort to head off the situation before it arises. Malthus, of course, was living at a time when travel was difficult and he could see his closed systems at almost the village scale. In the intervening years we have become more interconnected and the closed system is now the globe. Given that expansion, Pearce proceeds to deconstruct the assumptions that Malthus and those who have come after him have made: what is the current and immediate future population growth rate; how can we interpret migration; living within the limits; the age distribution and its social impact.

Population, as we might expect, is more complex than we might think, and, also surprising. Part of this is that Pearce examines his large canvas in minute detail. There are eastern european countries where population is reducing because there is no work and people are migrating. Many of these migrants were women, who moved to work rather than bring up children and so deprived both their original country and their new home of children. Rich countries have already seen this effect: women want to work and are choosing to delay a family. Unexpectedly, perhaps, the same is happening in the developing world. This is, in part, down to survival rates. A child is much more likely to survive to adulthood and women no longer have to spend all their time playing bad odds by flooding their lives with extra children. At the same time farming has changed, partly of necessity, since the workers have moved to the city, and the need for manual labour, particularly child labour, is no longer there. The result is lower fertility in both rural and urban populations. Contraception helps, of course, and this is more and more available despite the strictures of religion. Much of this comes down to the weakening of patriarchy. There is less pressure on women to conform to male expectations of wifely servitude, but even where such pressures exist, women are still making their own decisions about family size. The decrease in fertility rates is, it is important to emphasise, not driven by scarcity. Rather it is driven by better lives for women, and better health for children.

Breeding patterns of today have an impact on breeding capabilities tomorrow. China's one child policy did have an impact on population, but there was also an unexpected side effect. The Confucian concept of family requires a man to head the family - to make decisions and maintain honour. In China that meant that families were making sure that they brought up a male child by simply discarding any female child. Not all, but enough. The result is a population with relatively few women, which, coupled with women's choices of smaller numbers of children, means an overall reduction in fertility in relation to the total population. In parts of India similar things have happened due to the sheer expense of having a daughter - a daughter who marries must have a dowry from the parents, and dowry rates are not negotiable. The result is a lower percentage of girls; and accelerated population decline.

All these changes have two, linked, effects. One is that the global population will decrease, and the other is that population demographics are changing. Many of the changes in fertility started earlier in the richer nations and now they are rather short on manpower, unskilled, skilled and professional, and, correspondingly, people from developing nations are keen to fill these shortages. The rich nations are meeting this challenge by restricting entry. A repines that Pearce considers perverse, though, in practice, any attempt to normalise the position does require public acceptance of the economic and demographic necessities; something politicians are unwilling to address. Pearce's view is that migration can do nothing but good.

Having dealt with the assumptions of fertility rates, and shown us that we are living in a connected world, Pearce then looks at the realities of food scarcity and environmental impact. There are two or three things happening here. One is that the rich countries overwhelmingly produce more emissions than poorer countries, due to higher consumption, not population. He's working with pre-2010 numbers here but he states, for example, that "for the richest billion people people on the planet, their average consumption and production of waste is 32 times that of the remaining almost 6 billion".⁴ If a family in rural Ethiopia can have a large number of children and still do less damage than the average middle class western family, then accusing Ethiopians of miss-managing their population seems perverse, not to say unfair. And, while technology improvements and recycling have been making things better, it turns out that our consumption has run ahead of the gains. Even so, Pearce thinks it is possible for people to make meaningful changes that reduce or reverse environmental impacts. As one specific example, Costa Rica has reversed its destruction of forests, simply by changing government policies.

Food is where Malthus started, raising the question of whether the Poor could be supported by available land and agricultural capabilities. Pearce takes this forward to today's global position. Food plants and techniques for growing them have changed hugely since Malthus but these improvements appear to be self defeating: fertiliser run-off, top-soil erosion and seed patents are all causing problems. And lack of political interest has allowed these problems to sit there and fester until they have become almost too challenging for governments to face. So the problems are real, but, Pearce argues, not insurmountable. The good news is that biofuels and feed for factory farmed cattle take up more productive land than food directly consumed by people. Since we already feed everyone we can then postulate that a change in diet and reduction in biofuel would feed an expanded population. So will everyone eat vegetarian? Much of the poorer world does, so we are back to consumption by the rich.

Simple capacity is not enough; it never is. The global market distorts access to food; trade barriers, subsidies and local politics result in problems ranging from overuse of soils to forced export of crops that could better be used at home. Pearce, at this point, argues that the Rwanda genocide was politically driven and not a result of land shortages. The arguments are aimed at avoiding the simplistic "too many people" view. This fatalistic approach simply avoids addressing real issues and generally punishes poor people more than any other group.

Keeping the focus on Africa, it turns out that there is plenty of land available. What is lacking is the right approach, and, counter-intuitively, more people to put the approach into action. NGOs don't always help here. They tend to come up with standardised industrial monocultural solutions that have often lead to degradation of land rather than improvement. Local people have often come up with local solutions involving trees, water bunds and planting regimes that work with the local conditions. These require work, manpower, rather than money, so populations may need to grow to make it all succeed. Time is of the essence here. Some land is headed for a point of no return and land shortages will happen. Overall though, the outlook is good.

Even the cities are producing Malthusian tableaux that are not what they seem. Pearce points to slum cities as apparent examples of disasters in the process of unfolding. The paradox, though, is that city populations reproduce at more or less replacement rates; their growth is down to rural migration. Why migrate to a slum? Because the possibilities are better than they are in the country. To put it another way, the supposed shortages that might, in the Malthusian view, lead to unrest do not appear to exist. There are shortages, decent plumbing would be good, but these shortages are not absolute; they can be redressed by accepting that the slum exists and by working with the locals. Cleaning up the slums does not mean knocking them down. It means supporting the active local economy and enabling common goods, like clean water, drainage, power. The residents know what they want and often find ingenious ways to get it.

Pearce recognises that population will increase over the immediate term (his book was published in 2010) but it will decline in the medium to long term. This population decline means there is an increasing proportion of older people, currently so in the richer countries, but coming soon to other countries as the demographic patterns work their way through. Pearce sees this as having great potential for everyone; us oldies forming the glue that keeps society together. Altogether, he concludes that we are in for a real decline in population and we need to recognise this and plan accordingly.

Fred Pearce. 2010 Peoplequake; mass migration, ageing nations and the comming population crash. Eden Project Books. ISBN 9781905811342.