wild plants and animals into “domesticated” species that were more useful
to humans and were therefore encouraged to multiply rapidly. In towns and
cities, humans created entirely anthropogenic environments. There was little
that was not shaped by the presence of humans in even the oldest cities, such
as Ur. Increasing control over environmental
resources allowed humans to multiply
from about 6 million people 10,000 years
ago to more than 250 million people just
1,000 years ago.
The Modern Revolution has vastly increased
human impacts on the biosphere. Each of the
more than 6 billion humans on Earth today
consumes approximately 60 times as much
as energy as humans of the Paleolithic era.
These ¿ gures suggest that the total energy
consumption of our species has increased by about 60,000 times in 10,000
years. Most of this astonishing increase arises from population increase and
the introduction of fossil fuels during the Modern Revolution. John McNeill
estimates that in the 20th century humans became the most important movers
of earth, more important even than natural erosion. Mining had the greatest
impact on soil movements. As humans consume more resources, fewer are
available for other species. So rates of extinction have accelerated sharply
in the Modern era. Indeed, current rates of extinction may be similar
to those of the ¿ ve or six most spectacular extinction events in the last
600 million years. In the 20th century, humans engaged in a vicious and
prolonged war with the bacterial world after the introduction of antibiotics.
The outcome of this conÀ ict remains uncertain as bacteria develop new and
more resistant strains.
Finally, massive consumption of fossil fuels is increasing the levels of carbon
dioxide in the atmosphere, while other activities, including cattle farming,
are raising the levels of other greenhouse gases such as methane. The result
is that we are beginning to alter global climate patterns. Though there is
debate about many aspects of global warming, there is no doubt that the
level of carbon dioxide in the atmosphere has increased signi¿ cantly since
the Industrial Revolution. Will global warming cause changes as drastic as
The ¿ rst distinguishing
feature of our
species was a greatly
enhanced ability
to adapt through
collective learning.