An extraordinary milestone in the history of humankind will be passed next year. It will not have much discernible impact on many people's daily lives when it does occur and yet, within the spectrum of human experience, it will be a notable moment. For at some stage in 2008, a majority of the world's 3.3 billion people will, for the first time, be living in urban, as opposed to rural, areas. Thus man's progression from an agrarian hunter-gatherer to an urbanised industrialist will have passed a tipping point.
Attention to this pending moment in our history is drawn by the publication yesterday of the United Nations Population Fund's latest report, The state of the world's population 2007 - unleashing the potential for urban growth. On reflection, the fact that a majority of humankind will shortly be urban dwelling has a ring of inevitability about it. Man is, after all, quintessentially a social animal and gregariousness leads naturally to living in groups. Clusters of homes grow naturally into villages just as naturally those villages will over time (and economic prosperity allowing) transmute themselves into cities of many millions.
But despite this natural evolution, there is a deep seated anxiety about urbanisation even though people who live in cities are invariably better off when compared to their country cousins. Some negative western perceptions of urban life owe their origins to the rejection of city life implicit in the 19th century English naturalist movement. Its distaste for modernity was articulated emotionally - and brilliantly - in Jerusalem, the 1804 poem by William Blake with its contrasting images of the "dark Satanic Mills" of industrialisation versus the pastoral idyll of "England's green and pleasant land". Hogarthian images of urban slum squalor from an earlier period often seem to have a contemporary echo in the lives eked out on the fringes of decent existence in many third world cities.
And yet everywhere, the rural poor and dispossessed, the perennially hopeful, fortune seekers and would-be empire builders all continue to gravitate towards cities because it is in the cities that a better life awaits. The phenomenon is evident perhaps most dramatically today in China. The UN report notes that the potential benefits of urbanisation "far outweigh the disadvantages". But the disadvantages of unmanaged urbanisation - inadequate shelter, squalor, poor public health and social burdens disproportionately borne by women - can be avoided, as the report notes. The solution? "Providing minimally serviced land goes to the heart of the matter," says the report. And that applies to more than just the third world.