94 HUMAN ACTIVITY AND BIODIVERSITY
Poaching, forest clearance, and
other human activities have largely
contributed to the status of the African
western lowland gorilla as a “critically
endangered” species.Rapid population growth has
generated further damage to the
environment. The world’s human
population has risen from less
than 1 billion in 1800 to more than
7 billion, and is expected to reach
nearly 10 billion by 2050. As the
population grows, so do other
threats to biodiversity: increasing
numbers of invasive species are
spread through trade and travel;
urban development and resource
extraction destroy habitats; more
pollution is created; and land is
overharvested. The impacts of
human population growth will be
difficult to limit, as ever more
people rely on food and shelter to
survive, and demand ever more
goods in an increasingly global
consumer society.Upsetting the balance
Population growth also drives
overharvesting, the final human-
made threat to biodiversity in the
HIPPO acronym. Found in forestry,
livestock grazing, and commercial
agriculture, overharvesting can
also arise from targeted hunting,
gathering, and fishing, as well as
unintentional harvesting, such
as fish discarded from catches.Water pollution is caused mainly
by sewage or by chemicals
absorbed into water as it flows
off agricultural land. This pollution
reduces oxygen levels in water,
making survival more difficult for
some species, particularly when
combined with water temperatures
that have risen due to climate
change. Freshwater streams used
by certain species of spawning
fish, for example, can be made
uninhabitable by pollution.
Some organisms can absorb a
substance, such as an agricultural
chemical, more quickly than they
can excrete it, in a process known
as bioaccumulation. Initial, low
concentrations of chemicals may
not be a problem. However, as those
chemicals accumulate through the
food chain—from phytoplankton to
fish to mammal, for example—they
can reach levels that cause birth
defects and disrupt hormone levels
and immune systems.We should preserve
every scrap of biodiversity
as priceless while we
learn to use it and
come to understand
what it means
to humanity.
Edward O. WilsonEdward O. Wilson
Born in Alabama in 1929,
Edward Osborne Wilson was
left blind in one eye after a
fishing accident aged seven,
and switched interests from
birdwatching to insects. He
discovered the first colony of
fire ants in the US when he
was only 13, and later
attended the University of
Alabama and Harvard.
Wilson’s work has focused
primarily on ants but also
extends to the study of
isolated ecosystems, known
as “island biogeography.” A
leading environmentalist,
he has spearheaded efforts
to preserve biodiversity and
educate people about it. He
has been awarded over 150
prizes, including the National
Medal for Science, the Cosmos
Prize, and two Pulitzer Prizes
for nonfiction, and was named
one of the century’s leading
environmentalists by Time
and Audubon magazine.Key works1984 Biophilia
1998 Consilience: The Unity
of Knowledge
2014 The Meaning of Human
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