BIG BLOW HARD

I  nominate the island of Sumatra (above) as the earth's appendix. Stretching over a thousand miles from the northwest to the southeast, and up to 270 miles wide, it is evenly sliced asunder by the equator, and was built by earthquakes and 68 volcanoes,  making this island the most likely landmass on earth to eventually kill us all. If that is even possible anymore.

Off its south-eastern tip lies the treacherous 15 mile wide Sunda Strait, in which resides Krakatoa (above), whose explosive May 1883 eruption killed at least 36,000 people locally. 

In December of 2004, the Java trench (above) just off Sumatra's south-western coast was the epicenter for the 9.3 magnitude earthquake and resulting tsunami which killed 230,000 humans across the Indian Ocean.

There was also the 1815 eruption of 14,000 foot high Mount Tambora (above), which killed perhaps 11,000 locally and threw enough sulfuric acid into the stratosphere to turn 1816 into the “Year Without a Summer”,  destroying an entire season of crops across Europe, China and North America and thus killing another 60,000 through starvation and disease. 

But in the 12, 000 foot high Barisan Mountains on Sumatra lies the ultimate monster.  Lake Toba (above), is a water filled caldera 18 miles wide by 60 miles long. It was this tropical vacation spot which on a December or January day 71,500 years ago came very close to killing every human being on earth 

But back on that very bad day 71,500 years ago the once great Mount Toba had a lump of rhyoite stuck in its vent, preventing the magma in its six mile wide reservoir nine miles below the surface from exhaling. The pressures built up until, as it must eventually, something gave. Perhaps it was a minor earthquake along the Sumatra Fault. Perhaps, as at Mount St. Helens, it was a landslide that released the twin beasts beneath the mountain. 

The initial explosion was big enough, throwing tens of millions of tons of rock skyward, but it was also big enough to unleash an older, deeper magma chamber just to the north. The co-joined reservoirs were 17 cubic miles across. And the resultant combined explosion lasted an entire week, and threw ten trillion, trillion with a “T”, ten trillion tons of 1,500 degree Fahrenheit magma, rock and gas into the stratosphere. 

The eruption of Mount Toba was the largest volcanic explosion in the last 2 million years. The Toba ash fell in Greenland. The math says it caused 6 to 10 years without summers. Global temperatures dropped six degrees Fahrenheit. That makes it big enough to have killed almost every human on earth.  And that has been the accepted theory for decades.

Off course it was easier back then, because there were only about 55,000 primates walking around on two legs, divided, like a biblical tale of Cain and Able, into two family tribes; homo Neanderthal and homo Erectus. Now, it is important to remember we are talking about fewer humans than there are endangered Gorillas and Chimpanzees alive in the wild today. So killing all the humans on earth was not that big a job 71,500 years ago.

Erectus was the older brother, and the theory was that he left his African home first, taking his innovative hunter-gatherer life style on the road. It was Erectus' far flung prodigy who camped in the shadow of Mount Toba, 71,500 years ago. And according to research by geneticist Lynn B. Jorde at the University of Utah, the genetic markers passed down to us by our ancestors indicate a "bottleneck"

when the number of Erectus was reduced to a mere 10,000 individuals, maybe, even, as low as 40 “breeding pairs”. 

In other words, 70,000 years ago the total world-wide population of Erectus humans and Neanderthal humans could have attended a Sacramento Kings basketball game, with the stadium still left half empty, and the  “breeders”, scattered about in the corporate sky boxes.

But, half a million years before the Toba eruption, the more robust humanoids, named after Germany's Neander River valley where their skeletons were first uncovered, had moved into Europe and, it was once thought Asia as well.  

But 40,000 after Toba, Homo Neanderthals were extinct. The last survivors discovered so far were a  family group, camped in what is now Spain, and dated to no later than 45,000 years ago.  Why did they die out?  They weren't at Toba.  No Neanderthal bones have ever been uncovered west of Africa or the Carpathian mountains.

So what killed them off?  Well, we know that their body type required between 100 and 350 more calories per day than the ancestors of Homo Erectus, otherwise known as “us”. Or maybe it was a new family of viruses, or bacteria. The one thing we know for certain is that it wasn't the eruption of Toba, despite half a century of speculation that it might have been.

Sixty thousand years after Toba, human (Homo Erectus) populations had not only rebounded, but had grown to more than one million individuals world wide. This was primarily thanks to the invention of agriculture, but it was also a byproduct of the elimination of our competition -. Neanderthals.

In other words, as any supermodel can tell you, we are a better at surviving starvation, or at least better at it than Neanderthal was.  Hard to believe given the current population of fat assed Big Mac eating, French fry inhaling Americans. And maybe that explains our obsession with “all you can eat” buffets. 

The first problem with our mystical tale of a volcanic doomsday was uncovered in 2013, when  paleontologist working at Lake Malawi (above, bottom), at the southern end of the African Rift Valley, discovered a layer of 71,500 year old volcanic ash tied chemically to the Toba eruption. This was to be expected, and, given that the African Rift Valley was ground zero for human evolution, it should tie into any story about how humans were almost wiped out by the great Toba eruption. 

But the herds of wildebeests and antelope in the rift valley which human erectus were feeding off of were more far numerous then, than they are now. And their genetic heritage shows no Toba bottleneck. How could we starve if our food did not?

By 1804 the population of Homo Sapians sapiens (humans) had reached 1 billion individuals. And collectively we now weigh 100 times the biomass of any other land animal that has ever walked the earth. It would seem we have created enough people to no longer have to worry about becoming extinct because of some unlikely equatorial volcano. 

Maybe, 65 million years ago, instead of growing into the largest creature on earth, the Apatosaurus, should have chosen to invent the Whopper. Then they could have snorted at the meteorite that killed them.  Maybe.

Well, it turns out that just about the same time Toba blew its top 71,500 years ago, smallpox made its first appearance. We can surmise this from reading the bacteria's genetic clock. If we are reading it correctly.  Today, small Pox kills 40% of adults infected and 80% of children. Originally, it must have been much more deadly. In fact, it is far more likely that a tiny bacteria or an even smaller virus would produce a genetic bottle neck, rather than a big bad volcano, as anybody with a runny nosed six year old can testify. 

The Black Death (Yersinia pestis) killed about 200 million people in the 14th century alone – 1/3 of the population of Europe at the time. So what would have happened if a Mount Toba had erupted in Europe near the time of the arrival of the Black Death, or the first introduction of small pox?

Add Toba to just about any other disaster and together the pair could be a human ending event. This may explain, at least in part, why it has taken four billion years for a life form on earth to develop the cognitive power stand up on their own two legs and say, “I'll have a Big Mac with fries, please.”

The one thing we know about Toba is, it is going to do it again. Over the last million years, Toba has produced three major eruptions, one 840,000 years ago, a second 700,000 years ago, and the big one 71,500 years ago. The lake that fills the caldera is currently 1,600 feet deep, but beneath that is another 1,500 feet of sediment, created by the last 70,000 years of tropical rain fall.

The lava reservoir beneath the caldera has refilled enough to raise a resurgent dome in the middle of the lake, more than 3,000 feet above the water. It has been named Samosir Island. At 30 miles long, 15 miles wide, and 247 square miles in area, it is the largest island within an island in the world. And it contains two lakes with their own islands. This appendix is reloading to rupture again. Should we be worried?

I would be, if I didn't have anything else to worry about, like Covid or taxes.  And worrying, just worrying, that will kill you, for sure.

- 30 -