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!