The Sixth Extinction: The Middle of the End

June 08, 2015
Dinosaurs

Someone’s feeling awfully smug… Oh wait…

Our geological era, often called the Anthropocene in honor of its most influential characteristic, has been a remarkable period in Earth’s history. For her book, The Sixth Extinction, Elizabeth Kolbert travelled extensively to produce a stunning account of just how remarkable it has been. In addition to all the history we all know, this era has overseen the extinctions of a nearly uncountable number of large land animals; the mammoth, the ground sloth, giant tapirs and giant apes, phascolonuses and moa. It has seen changes in oceanic and atmospheric chemistry that are, as best as we can tell, wholly unprecedented in the 4.5 billion year history of our planet. Never before have changes of such magnitude come so quickly. The Sixth Extinction explores not only what we know about these events, but how we know it. Mrs. Kolbert’s research took her from one end of the world to the other, and the overwhelming preponderance of evidence seem clear and compelling: unless something changes, the future is going to be a very ugly place for our descendants.

While the science is exciting, her book is also depressing. She doesn’t seem to be writing to provide one with any particular hope. She writes with excitement and energy, and the scientists she speaks to are deeply passionate and committed to their studies. But they share gems like these:

“Within the next fifty years or so, ‘all coral reefs will cease to grow and start to dissolve.’”

“We are losing all these amphibians before we even know they exist.”

“It is the rate of CO2 release that makes the current great experiment so geologically unusually, and quite possibly unprecedented in earth history.”

And then she steps back for a moment. After delivering a blow-by-blow account of our crumbling global ecosystems, she turns her attention to the Neanderthals. The Neanderthals are interesting, she explains, because they are our very close cousins. In fact, the odds are very good that if you’re reading this, you carry several Neanderthal gene sequences in your DNA; some long forgotten relative our yours was one. You might have been able to have children with one yourself, but you can’t – they’re all dead. As best as we can figure, early humans either overwhelmed the population genetically (bred them away), or killed them all. But what makes them interesting is that, despite all we shared with them, Neanderthals never actually did much. Aside from the evidence of ritual burial, they ranged and lived much like other large mammals. The impact they had on their environment was negligible.

And they weren’t alone. We have found mounds of evidence for human-like species that existed alongside our own, but none of them took the extraordinary steps that ours did. Neanderthals ranged into Europe during a time when the Mediterranean basin was empty. As it filled, they spread around the continent until at last they could no longer return. Humans crossed oceans and delved into caves. Humans took risks and explored their surroundings in a way that their cousins must not have thought to match.

Why would our ancestors cast themselves out onto the oceans and into the unknown? It takes a kind of mad faith for any land animal to take such an extreme step—most treat the open ocean with a degree of trepidation. But not humanity. Instead we decided to float across vast seas on beds of reeds and logs. Sometimes it worked, though we can imagine that many of those earliest pioneers never found anything. Mrs. Kolbert describes the origins of this behavior as the “madness gene.” As she says, “A tiny set of genetic variations divides us from the Neanderthals, but that has made all the difference.”  Those twists in our DNA that gave rise to these behaviors has marked us out from the rest of the animal kingdom ever since.

Because, while her storytelling is masterful, and her evidence both terrible and irrefutable, there’s something troubling with the picture she paints: it puts man at the center of a huge variety of planetary changes. We spread further than any other species. We hunted entire races to extinction, and delivered new pathogens and new animals into completely alien ecosystems, often with devastating effects. No race, nation, culture, or creed is spared this basic condemnation. Our ancestors, unaware of their uniqueness and their power, began the process of remaking the planet from the moment they set out from Africa. The resulting ecological genocide is something of an original sin that we inherit from our ancient line.

And this is troublesome. In researching this article, I decided to take a quick look at the Wikipedia page on the “Holocene” or “Anthropocene” extinction. I needed a short list of species known to have gone extinct during the period. Instead, I found a spirited defense of the first humans to reach North America; the so-called Clovis culture. The article insisted that whatever evidence there was, none was sufficient to irrefutably tie the early Clovis to the demise of these wondrous megafauna. The writer was passionate, insistent, and not even remotely interested in the question of the animals themselves. He was protecting something; an element of faith perhaps? Note: this is hardly the only article on the subject; most of the rest are written far less defensively.

The Clovis Culture is believed to be the first human society of any size to establish itself in North America – the ancestors, perhaps, of modern Native Americans. We don’t know for sure, but what is known is this: Immediately after our earliest evidence for the arrival of the Clovis peoples (geologically speaking), most large land animals in North America disappeared. This fact probably had massive climactic and ecological impacts on North American biomes. It changed the nature of the much local vegetation, and may even have had global effects. We actually see evidence for this around the world; Australia, Europe, North Asia; the confluence of these facts has always irked some people. Whether native groups who feel their legacies and heritage have been somehow poisoned, or those who cannot accept that their actions can affect the world in any way; it seems that recognizing our identity as a species still must wait until we satisfy our identities as individuals. Maybe then we can start taking the sixth extinction seriously. Our “madness gene” may have driven us to the extreme ends of Earth, but it has also given us the power to shape destiny.

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