24 Mark Perlman
example, it is not well known that the shape of Niagara Falls (on the U.S.–Canada border)
is not what the water eroded naturally—its appearance has been partly engineered
by humans. For one thing, 50 to 75 percent of the river’s water is diverted upstream by
tunnels for hydroelectric power generation, so the falls have much less water than
they would naturally. Furthermore, the very shape of the falls has been carved by human
intervention, dynamited to blast off loose rock and bolted together (while the water source
was blocked to leave the falls dry) to secure the rock and reduce the natural erosion (see
fi gure 2.5). So while the presence of a large waterfall in that location is natural, the exact
appearance of Niagara Falls has been signifi cantly affected by intentional human
intervention.^1
For very large-scale human alteration of nature, consider global warming. It has become
clear now that human activity is increasing the average temperature of the entire planet,
such that nothing can be said to be truly “natural” if by that we mean untouched by human
tampering.
One might attempt to retain the distinction between natural and artifi cial functions
by admitting that there is no hard distinction between natural and artifi cial objects but
insisting that the functions of these objects can be divided into two distinct kinds—natural
and artifi cial. The functions may remain separable even if many objects have a hybrid
status. Such a view would be tempting if the kind of human action on natural objects was
a recent phenomenon, an innovation of the technological age of the past century or two.
But human intervention in nature is not really new—we have been breeding domesticated
animals for thousands of years. Moreover, we are ourselves produced by nature, so one
wonders how our behavior can be so fully deemed unnatural. It may well be that recent
technology has greatly increased the magnitude of human alteration of nature, but the
existence of human changes to the natural world with biological and geological artifacts
predate recorded history. So what exactly separates the supposed functions into two dis-
Figure 2.5
The “American Falls” of Niagara Falls, seen currently (left) and in 1969 (right) when water was blocked off for
“restoration.”