From a reoccurring global event to species
disappearing at alarming rates, here’s what
they won’t tell you about the 6th extinction:
Number 9 Holocene Extinction
In broad terms, a mass extinction event is
a large-scale rapid decrease in the planet’s
biodiversity.
It essentially takes places when the rate
at which biological species die out is much
faster than the rate at which new species
are formed.
Evidence suggests that there have been five
previous major mass extinctions throughout
our planet’s history and that we’re currently
living in the sixth.
Yet, while past events were inevitable, the
result of natural processes, the ongoing Holocene
extinction is a direct result of human activity.
The 6th extinction coincides with the epoch
that we’re currently living in, called the
Holocene, which began roughly 11,650 years
ago at the end of the last Ice Age.
Some scientists have proposed an additional
boundary between the Holocene and a new epoch,
called the Anthropocene.
The term, although not officially approved,
would mark the period when human activity
started to significantly impact the Earth’s
geology and ecosystems.
Various thresholds for the Anthropocene have
been proposed, ranging from a few thousand
years ago to the dawn of the Industrial Revolution.
Number 8 First Extinction Event
About 2.4 billion years ago, our planet’s
atmosphere and the shallow ocean underwent
a rise in oxygen.
It’s still unclear why, but in time, it
enabled the rise of new living organisms as
more free energy was available.
This event is known both as the Oxygen Revolution
and the Oxygen Holocaust.
Even though the accumulation of oxygen allowed
life as we know it to take shape, it also
killed off the anaerobe species existing at
the time.
This is believed to have been the Earth’s
first mass extinction.
Quiz Question
Before we move on, answer this question.
Which of these extinction events meant the
end of nearly all dinosaur species?
Was it
a.
Permian-Triassic
b.
Late Devonian
c.
Triassic-Jurassic
d.
Cretaceous-Tertiary
Let us know what you think in the comments
section below and stay tuned to find out the
right answer.
Number 7 Megafauna
A few thousand years ago, at the dawn of the
Holocene, humans coexisted with woolly mammoths,
giant sloths and saber-toothed tigers.
There’s an ongoing debate of whether these
species and many others became extinct due
to climate change, over-hunting by humans
or a combination of the two.
There’s no doubt that the Earth’s climate
underwent some drastic changes at the end
of the last Ice Age, which affected the habitat
and food sources of many large animals.
Nevertheless, there’s often a direct correlation
between the arrival of humans to new lands
and the subsequent decrease in megafauna populations.
In Madagascar, for example, animals weighing
over 330 pounds went extinct very shortly
after human arrival.
Humans arrived in Australia when it was home
to numerous species of megafauna, about 50,000
years ago.
Within 4,000 years, all of the continent’s
animals above 220 pounds were extinct.
The rate of extinction was comparatively slower
in Africa, Europe and Asia, where megafauna
evolved alongside humans and presumably learned
to fear them.
Superior intelligence and adaptability, traits
that evolved throughout the Stone Age, made
humans, global super predators.
This basically meant they were capable of
hunting any living thing.
Then there’s the theory that animals travelling
with humans, such as domesticated dogs or
livestock, spread diseases that megafauna
had no immunity to.
Nowadays, species of megafauna are almost
exclusively found on the African continent,
where their populations are rapidly declining
due to poaching or loss of habitat.
Number 6 Loss of Habitat
Agriculture developed around 11,500 years
ago and it’s the foundation upon which our
civilization was built.
About 10,000 years ago, sheep, pigs and cattle
were domesticated.
In the early days, population growth was dependent
on how much land was used for farming.
Human beings gradually transitioned from a
hunter/gatherer lifestyle to permanent settlements.
This meant, they no longer exclusively relied
on their environment for sustenance and that
they could control the food they produced.
In the years following the emergence of agriculture
and domestication, up to present times, wild
animal populations have decreased as a result
of human activity.
Industrial agriculture gradually took the
place of subsistence agriculture and the need
for more land grew.
Deforestation has led to the fragmentation
or destruction of wild animal habitats, particularly
for megafauna which require larger territories.
Fragmentation, especially when the remaining
habitat is small, may facilitate the path
to extinction.
Deforestation is one of the driving factors
behind defaunation, an ongoing process which
includes both the extinction of animal species
and their decline in numbers.
The results, seen all-over the world, comes
in the form of “empty forests”, a term
describing ecosystems that aren’t inhabited
by any large mammals.
Number 5 Domestic Versus Wild
One study has indicated that approximately
60 percent of biodiversity loss may be attributed
to the large scale feed crop cultivation,
required to feed billions of farm animals.
One recent example is the conversion of significant
portions of the Amazon region to agricultural
terrain, for meat production.
By some estimates, over a quarter of the planet’s
ice-free land is used for cattle grazing.
Controlling the animal food source has meant
supporting an ever-growing human population
and opening a pathway to economic growth.
The rapid rate of expansion was detrimental
to the habitats of wild animals.
Recent studies show how livestock accounts
for 60 percent of the total mammal biomass,
humans account for 36 percent, whilst wild
animals account for 4 percent.
The same tendency is noticed in poultry where
the biomass of domestic birds is three times
greater than that of wild birds.
Many experts have argued that this acceleration
in food production is no longer strictly connected
to feeding the human population, since estimates
have shown that approximately a third of all
food that’s produced is thrown away.
Number 4 Invasive Species
Here’s a thought experiment that has been
the base for numerous works of science fiction.
Let’s suppose that a technologically superior
extraterrestrial species lands on Earth, by
accident, and finds all our resources to be
compatible with their needs.
Our survival would be significantly threatened
in the ensuing competition.
It’s one of the principles upon which invasive
species function.
Non-native species can directly prey upon
or out-compete those already existing in an
area.
They can also modify the habitat so that survival
for the natives becomes impossible.
Human activity has intentionally or inadvertently
influenced the spread of invasive species.
For example, the Asian tiger mosquito, a carrier
of dengue fever and West Nile virus, spread
to the continental US through a shipment of
used tires.
The Burmese python, which is decimating native
animal populations in Florida, was introduced
via the pet trade.
The brown tree snake arrived in Guam by crawling
into the landing gear of an aircraft.
It grew to staggering numbers and all but
eliminated the vertebrate population in the
local forest.
Number 3 Ocean Pollution
The Holocene extinction has affected the world’s
oceans in a number of ways, one being pollution.
Rising levels of carbon dioxide have led to
an increase in ocean acidity.
This puts pressure on marine creatures that
have exoskeletons or calcium carbonate shells,
as they react with the acid.
A number of coral reefs around the world,
which were once rich habitats, have become
bleached and void of life.
Almost ten million tons of plastic, mainly
consisting of single-use plastics, are being
dumped into the ocean every year.
If the current trends continue, the mass of
plastic in the ocean might outweigh that of
fish, by 2050.
Cleanup is difficult because the single-use
plastics, such as shopping bags, break down
into smaller particles called microplastics,
which can affect a wide range of marine creatures.
Quiz Answer
So which extinction event marked the end of
the dinosaurs?
If you chose d, Cretaceous-Tertiary, then
you’re right.
Also known as the Cretaceous-Paleogene extinction
event, it occurred roughly 66 million years
ago and was triggered by a massive asteroid
hitting the Gulf of Mexico.
Measuring 6 to 9 miles wide, upon impact,
it released energy equivalent to several million
nuclear weapons going off at the same time.
Number 2 Extinction Rates
Over the past hundred years, vertebrates have
been dying out up to 114 times faster than
they would have without human activity, according
to one study.
This means that species that would’ve naturally
become extinct in 11,400 years, did so in
a century or less.
These, however, are highly conservative estimates.
According to Professor Gerardo Ceballo, the
lead researcher in the study, “Our activities
are causing a massive loss of species that
has no precedent in the history of humanity
and few precedents in the history of life
on Earth.”
Former president of the American Association
of the Advancement of Science, Peter Raven,
claims humans have driven the rate of biological
extinction up several hundred times beyond
the levels previously seen in history.
He fears a loss of the majority of all species
by the end of the 21st century.
Number 1 Overexploitation
Humans are described as unique super predators,
because they can hunt nature’s apex predators
in any environment on the planet.
For example, whaling has reduced cetacean
populations over the years.
Even blue whales, the largest creatures in
existence, were almost hunted to extinction
over the course of a century.
Fishing already had a devastating effect on
marine environments even before the introduction
of highly effective practices like trawling
or the use of explosive harpoons.
Poaching and overhunting are significant driving
factors of defaunation.
Game animals have been hunted both for their
meat and for products derived from their skins,
hides, pelts, furs, bones and internal organs.
As of 2019, 70 percent of the 362 species
of megafauna are in decline.
Big cat populations have gone down dramatically
and, if current trends continue, they’ll
be extinct in a matter of decades.
Rhinos and elephants have been hunted extensively,
often illegally, for their horns and tusks.
The last male northern white rhino died in
March 2018.
Giraffes, non-human primates and rhinos are
just a few of the species expected to disappear
completely in the near future.
Before Europeans colonized Africa, the continent
was home to about 20 million elephants.
Today, the number is below 400,000 and if
poaching rates continue African elephants
could become extinct by 2035.
A few years ago, over 15,000 scientists issued
a warning to humanity to put practices in
places that would halt “defaunation, the
poaching crisis and the exploitation and trade
of threatened species.”
Thanks for watching!
Would you rather…be present during a mass
extinction and not know when it’ll happen
or know the exact date you’ll die?
Let us know in the comments section below!
