We are on the brink of Earth’s sixth mass extinction. For the first time in the history of our planet, most of the world’s species will disappear not because of an unavoidable natural cataclysm or geological event, but as a direct result of human activity. And as hard as it may be to accept that we are responsible for the instability of the natural world, it is even harder to believe that this catastrophe was triggered by humans thousands of years ago.
A mass extinction occurs when the historical extinction rate of species reaches alarming levels in a relatively short period of geological time. Astounding as it may sound, the current devastation of Earth’s Biodiversity has actually been the trend since even before the beginning of the Holocene Epoch (which began roughly 11,700 years ago), at the verge of human civilization.
By looking at the chronological order of defaunation in various regions and comparing it to the history and prehistory of humanity and its migration patterns, it is easy to spot the correlation between both variables — innumerable species, especially those weighing over 45 kg (or 100 lbs), have gone extinct everywhere humans have settled.
Australian Megafauna Vanished With The Arrival Of Humans.
Researchers from the Monash University in Victoria, Australia and the University of Colorado Boulder, recently discovered spores of a large fungus that thrived on the dung of ancient large mammals. By studying the abundance of these spores, they came to the conclusion that the presence of megafauna in Australia collapsed around 45,000 years ago, after the arrival of the first human settlers.
Evidence suggests that humans reached continental Australia 65,000 years ago. They coexisted with large mammals for almost 20,000 years until driving many to their extinction. The extinction of the 2-meter tall Genyornis, for instance, is mainly attributed to human activity as the climate of the alleged time of its disappearance 40,000 years ago was stable, ruling climate change out of the equation.
Giant birds were not the only large creatures present in ancient Australia. Oceania was home to incredibly large reptiles and marsupials. For example, the largest marsupial to have ever lived on our planet, Diprotodon, lived in this region, but, this giant predecessor of wombats became extinct 50,000 years ago, coinciding quite flawlessly with the arrival of humans in Australia.
Of course, many species died out due not to just one factor, but to a combination of many, including climate change, over-hunting, and deforestation. Nevertheless, it is indisputable, with respect to Australia’s ancient megafauna, that the years between the demise of many animals and the arrival of humans match up almost too perfectly, as so it does in many other parts of the planet.
Mass Extinction During The End Of The Last Glacial Period.
The melting of the ice cap of the northern hemisphere of Earth laid the foundation for the rise of European tribes and the arrival of humans in the Americas. Hunting became widespread, and early farmers eradicated large predators and herbivores to protect both their livestock and their cultivations. Human settlements together with the end of the Younger Dryas marked the beginning of the destruction of megafauna across several Northern regions of the planet.
Before human settlers migrated across the Bering Strait into the Americas, the Northern and Southern continents were home to some of the most fascinating creatures to have existed. Smilodon fatali, infamously known as the sabre tooth tiger, coexisted alongside the lesser-known American lion and the giant short-faced bear. Woolly mammoths roamed the upper regions of North America whilst the enormous ground sloth and glyptodon ventured around the lower regions.
Contrary to popular belief, Europeans did not introduce horses to the Americas, North American horses and even North American camels were present in the Northern region long before European settlers arrived. The biodiversity of the Americas was beyond belief until its downfall 11,700 years ago.
On the other side of the Atlantic Ocean, Eurasia shared an equally interesting biodiversity assortment during the last ice age period. It is difficult to imagine this region as a wildland for large vertebrates other than those that inhabit it today — bears, wolves, bison, and elks. But, in reality, Europe was teeming with megafauna less than a millennia ago. Aurochs, woolly rhinoceros, straight-tusked elephants, cave lions, cave hyenas, and elasmotherium were all part of this great Eurasian biodiversity, but just as the megafauna in North America, most Eurasian wildlife died out at the end of the Pleistocene Epoch.
The mass extinction of megafauna in Eurasia and the Americas is accredited to the “overkill” of human hunters and to the sudden changes in global temperatures during the Last Glacial Period. Nonetheless, studies indicate that the causes varied across different regions — in some regions, hunting was the driving factor whilst in other regions climate change was the main cause.
The Most Recent Massive Extinction Event Was In Madagascar.
Madagascar was home to some of the most exotic megafaunas of the planet. It was home to giant lemurs, giant tortoises, crocodiles, and 3-meter tall elephant birds, just to mention a few. Be that as it may, this island country located on the East side of Africa also witnessed a mass extinction event just between 700 A.D. and 1000 A.D. and its megafauna disappeared completely with it. What was the cause?
Scientists have studied the stalagmites in various caves within the island to see if climate change had anything to do with the abolition of the giant animals. Could the island had suddenly dried up sometime in the past that caused this extinction event? The results point towards a stable humid environment. In fact, 780 A.D. to 960 A.D. were some of the wettest periods of the last 2000 years. There’s only one other explanation: human activity.
Evidence of butchery found in ancient Aepyornis bones shows that humans settled in Madagascar 10,500 years ago. Humans in the island sustainably hunted and coexisted with its megafauna for almost 9,000 years, until they dramatically changed the ecosystem of the region through deforestation and farming.
The stalagmites and pollen grains buried in ancient Malagasy lake sediments reveal a dramatic change from a forest-dominated ecosystem to a grassland-dominated ecosystem. There was a sudden increase in forest fires and the presence of the fungus, Sporormellia (found in grass-eating animal dung), suggests an increase in livestock populations. In addition to that, cut marks on bones show humans continued hunting to supplement their diets even though they now had livestock to feed on.
The Remaining Megafauna Of Our World.
Today, Africa, Euroasia and East Asia are the only regions of the planet that house some of the last remaining giant animals (such as elephants, giraffes, rhinos, and lions). These three regions seem to have been the only places where large animals learned to see humans as threats and avoid them. Their safety, however, is no longer guaranteed. Africa was once home to about 20 million elephants. Today, their numbers are below 400,000. There is an ever-increasing human population of consumers of goods that are directly impacting the biodiversity of our planet and this is our final call.
In essence, the history of the mass extinction of megafauna teaches us that there are three main driving forces behind the defaunation of the planet that need our attention: climate change, unsustainable hunting, and deforestation. Coincidentally, these are exactly the three biggest concerns behind the sixth mass extinction we are witnessing today.
In Africa, for example, megafauna and other animal populations are rapidly declining due to poaching, game-hunting or loss of habitat. In the oceans, overfishing is eradicating fish populations, such as tuna, as well as porpoise populations and other marine life. Rainforests, such as the Amazon Rainforest and the New Guinea Rainforest, are estimated to disappear within a century at the current rate of deforestation. Global warming is causing poles to melt and heat waves to form intensively in many countries. Many species are being affected by this alarming rise of global temperatures, including the human species.
70% of all the remaining megafauna is in rapid decline as of 2019.
Vertebrates are dying out 114% faster than the average historical rate, a figure which has no precedent in the history of mankind. In other words, we are about to witness the extinction of the last large animals on the planet in a matter of decades. Giraffes, rhinoceros, big cats, non-human primates, elephants will all be extinct by 2050 unless we address the problems affecting the natural world today.
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