People have a greater influence on animals than they
realize. The extinction of animals is inevitable, and
it is believed that about 99.9% of all species to have
existed have gone extinct. However, the rate at which
species become extinct is currently the highest it is
known ever to have been; for the first time since the
extinction of the dinosaurs, organisms are losing genetic
diversity and becoming endangered and extinct at a higher
rate than that at which they can evolve to survive changes
in their environment. This ongoing event is often referred
to as the sixth mass extinction, and is caused most
notably by human activity.
Habitat change and destruction is the leading cause
of extinction; though habitat destruction occurs in
nature, it has been afflicting populations at an accelerated
rate in recent years due to human activity. Humans build
homes and towns in animals' habitats, cut trees for
timber, and clear land as farmland, usually destroying
the habitat of whichever species live in these ares.
Destroying the habitat in an ecosystem subjects the
affected populations to devastating effects such as
the loss of food and shelter, making the continued survival
of affected species tenuous and, eventually, impossible.
Humans also contribute to this leading cause of extinction
extinction by causing dramatic climate change. Since
the industrial era, human activity has caused the accelerated
release of greenhouse gases and aerosols into the environment,
trapping heat in the atmosphere and contributing to
global warming. In addition to posing a potential serious
danger to human health, environmental change contributes
to or causes the extinction of vulnerable animals, or
those overspecialized to their environments.
Humans may also cause extinction through means other
than habitat change and destruction. Poaching, notoriously
responsible for endangering many species, may also become
a very serious threat to the survival of several species.
If many animals of one species are killed by human hunters,
there may eventually be too few organisms left to breed
enough to repopulate, and the species may become extinct.
Many fear that this is the looming fate of animals such
as elephants and rhinoceros, which have been controversially
subject to much poaching.
Poaching may also reduce the viability of several of
the animals it affects. By killing several animals in
a population, poaching reduces the genetic variability
within a population, subjecting future offspring of
its animals to health complications due to inbreeding.
This effect of poaching may prevent several animals
in a population from surviving to sexual maturity, and
therefore mating, reducing the number of animals in
a population over the course of several generations.
Though this effect of poaching alone may not effect
extinction, it can severely hurt a population, contributing
significantly to its endangerment and eventual extinction.
Because of human activity, extinction is becoming an
increasingly prevalent danger to Earth's biodiversity.
Biodiversity is important because it is necessary long-term
to sustain ecosystems. As the health and survival of
ecosystems often depend on various predator-prey relationships,
the extinction of a species may have devastating effects
on the ecosystem to which it belonged; when the diversity
of life on Earth is harmed, so is the ability for the
rest of Earth's life to sustain itself. Furthermore,
many people appreciate biodiversity not only for its
cultural, aesthetic, and educational value, but for
its providing a variety of food sources, research opportunities,
and medicinal resources; biodiversity is therefore,
to humans, worth protecting.
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