Living Sanibel: The benefits of extinction
Nature is chaos. Chaos is nature. Darwin was wrong. The concept of survival of the fittest, with each and every organism slowly adapting to minute changes in their environment over the millennia, is only half the story. Darwin’s theory of evolution is known as gradualism.
Starting in the 1950s, and culminating in a paper by Walter and Luis Alvarez in 1980, a new concept of evolution took root called catastrophism. This theory contends that although all living things can and will adapt to their environments over time, the stability of those environments is by no means a certainty. Environments change, sometimes in an instant.
The basis of the Alvarez paper lay in a thin slice of inexplicable clay in rock formations found in central Italy. Analysis of the clay indicated it contained rare minerals formed under extreme heat and pressure. The Alvarezes (father/son) concluded this layer of clay, found in the same strata everywhere on earth, could only have been caused by a massive meteor or comet strike occurring 66 million years ago.
At first the scientific community dismissed his concept as absurd. But on March 10, 2010, some thirty years after the publication of the original paper, a panel of 41 scientists agreed that the 110 mile-wide Chicxulub crater, located off the Yucatan Peninsula in Mexico, was the site of the cataclysm. The dinosaurs didn’t have time to adapt.
Evidence now indicates almost all the various species of dinosaurs perished in a few thousand years. The firestorms, mega-tsunamis and shockwaves resulting from the impact altered the environment dramatically and instantly. The 186-million-year reign of reptiles was over.
We are the direct beneficiaries of this planetary disaster. Out of the ashes of the Chicxulub crater crawled small, rat-like omnivores that survived on a diet of detritus and carrion. Over the next 66 million years those primitive mammals evolved to fill the many niches left by the extinct dinosaurs. This process eventually gave rise to monkeys, apes and, ultimately, Homo sapiens. Without the errant meteor slamming into Mexico, you wouldn’t be reading this article. Chaos happened. We were the lucky winners.
That event is now referred to as the fifth extinction or the “Great Dying.” The four preceding it were the End Ordovician (450 million years ago), the Late Devonian (374 million years ago), the End Permian (251 million years ago) and the End Triassic (200 million years ago). The causes of these four earlier mass extinctions are still being debated. The worst of them, the End Permian, eradicated 96 percent of all marine life and 70 percent of all terrestrial vertebrate species. The world’s oceans mysteriously became acidic and possibly anoxic (lacking oxygen), which some believe resulted from a drastic rise in carbon dioxide. What caused the spike in CO2 is still unknown but volcanism is the most likely suspect.
In fact, a volcanic event of extreme proportions almost wiped out the human race 70,000 years ago. It happened on the island of Indonesia and was the largest volcanic disaster on Earth in the last 25 million years. It is called the Toba eruption and has spewed as many as 670 cubic miles of ejecta into the atmosphere. That’s 22,000 times more than the .03 cubic miles of dust and debris that came out of the 1980 Mount St. Helens eruption. The scope of an eruption of this magnitude is unimaginable.
Scientists believe the Toba eruption triggered a volcanic winter that sent global temperatures plunging by five to nine degrees Fahrenheit. Worldwide, all plant life was impacted for at least a decade and the human population at the time was reduced to between 10 and 15,000 mating pairs. In parts of nearby Malaysia the ashfall was 30 feet thick.
Today we live in the shadow of another super-volcano, Yellowstone National Park. It last erupted 640,000 years ago and ejected 240 cubic miles of rock, dust and volcanic ash into the sky. Were the Yellowstone caldera to erupt at that same magnitude today, the devastation would be incalculable. The history of our planet is rife with these kinds of sudden and dramatic events, lending ever more credence to the Alvarez theory of catastrophism.
Today many scientists believe we are in the midst of the sixth extinction. This one is not caused by a meteor impact, a carbon dioxide release or a super-volcano, but by a species of ape that came out of Africa 180,000 years ago. The sixth extinction will be the topic of my next article in this series…The Human Footprint.
Charles Sobczak lives and writes in Sanibel Island. He is the author of several books including “Living Sanibel” and “The Living Gulf Coast.” He will be doing a powerpoint presentation entitled “The Human Footprint” at the Bailey-Matthews National Shell Museum on Jan. 7, 2015 at 2 p.m. Plan to join Mr. Sobczak if you are interested in learning more about our impact on the planet.