Geography Reference
In-Depth Information
for the i rst time in our history, more of us lived in cities than outside of them.
Each year seventy-two million more people l ock to cities. By 2050 more than
two-thirds of all humans are expected to live in cities.
The city itself is only a part of the urban niche we have constructed. Like
a galaxy, moderately large cities spin of suburbs, small edge cities, and a dis-
tant fringe of settlement called “exurbia”—“a semirural area beyond suburbia
yet within its shadow.” This gradient of urbanization from a densely popu-
lated urban core to a lightly peopled exurban fringe is dependent econom-
ically and socially on the commerce and culture of the city. The human census
acknowledges this connection as it classii es Earth's residents. In the United
States, for example, if we live in a city (areas with more than one thousand
people per square mile) or in the associated less dense areas (at least i ve hun-
dred people per square mile) connected to these cities, we are called “urban.”
In the 2010 census, as a resident of exurban Seattle, I became one of the urban
people because the population density in my neighborhood crept over the
lower critical threshold. Although my neighbors and I live on an average of
two acres each—one hundred times more land than the residents average in
the world's most densely settled city, Dhaka, Bangladesh—we are all urban-
ites. Our urban niche now includes commercial, industrial, and residential
lands as well as their interstices of protected reserves, green recreational areas,
and waterways.
It staggers me to contemplate the implications of our new lifestyle. We
now live predominantly in a niche that was unknown only six thousand years
ago! Generations of city people no longer have the interest to live in the coun-
try and may truly struggle to survive doing so. The social customs, diet, cli-
mate, modes of communication, and transportation in the city would be as
foreign to our ancient ancestors as theirs would be to us. We have evolved into
a new ecological role with cultural barriers to our rural legacy. Evolutionary
biologists might consider us well along the process called “anagenesis”—the
