Towns and cities have a long history, although opinions vary on which ancient settlements are truly cities. The benefits of dense settlement included reduced transport costs, exchange of ideas, sharing of natural resources, large local markets, wider selection of potential mates, and in some cases amenities such as running water and sewerage. Possible costs would include higher rate of crime, higher mortality rates, higher cost of living, worse pollution, traffic and high commuting times.
Cities grow when the benefits of proximity between people and firms are higher than the cost. There is not enough evidence to assert what conditions gave rise to the first cities.
Some theorists have speculated on what they consider suitable pre-conditions and basic mechanisms that might have been important driving forces. Smaller human settlements such as villages pre-date cities by many thousands of years.
Before permanent settlement in cities, there were also large temporary settlements used for religious purposes or as a stopping place for nomadic people. The conventional view holds that cities first formed after the Neolithic Revolution. The Neolithic revolution brought agriculture, which made denser human populations possible, thereby supporting city development.
The increased food production per unit of land supported higher population density and more city-like activities. In his book, Cities and Economic Development , Paul Bairoch takes up this position in his argument that agricultural activity appears necessary before true cities can form.
