Lake Toba

          Lake Toba has been described as the largest lake in Southeast Asia.  It is approximately 1130 km², approximately 100 kilometers long by 30 kilometers wide.  It is a huge caldera filled with water and you can see from these photos that it looks just like what it is: the top of a huge mountain that blew off and filled up with water. 

       

Somewhere between 67,500 and 75,500 years ago Toba erupted into a super volcano.  It was quite simply the biggest volcano in 25 million years.  It is estimated that it ejected about  2800 cubic kilometers or 670 cubic miles of ash, lava and other material.  Scientists estimate that approximately 2000 cubic kilometers of lava flowed from the eruption and 800 cubic kilometers or 192 cubic miles of ash blew out of the eruption.  To give you an idea of its magnitude, scientists believe that it deposited a layer of ash 15 centimeters thick over the entire Indian Subcontinent.  In parts of Malaysia the ash was 9 meters (almost thirty seven feet) thick.  Today, the ash layer around Lake Toba is up to 6 meters deep.   Scientists have also estimated that Toba blew out anywhere from ten thousand million to six thousand million metric tons of sulphuric acid into the atmosphere.  By contrast, Mt. St. Helens ejected only about 1 cubic kilometer of material.  The 1883 eruption of  Mt. Krakatoa  (between the Islands of Java and Sumatra) ejected approximately 21 km³ (5.0 cu mi) of lava, rock, ash, and pumice.  The next largest supervolcano eruption known to man occurred  in Idaho about 2.1 million years ago and blew out about 2500 cubic kilometers of material.  But Toba was more than three times the size of the last eruption to have occurred at Yellowstone National Park (well before it was designated a National Park) about 630,000 years ago.  Just in case you think we are living in a dangerous area here in Indonesia,  just remember the US was a hot spot too at one time, and according to a rather breathless report on the Discovery Channel, Yellowstone could blow again anytime in the next 500,000 years. 



Satelite photo of Lake Toba

             In the center of Lake Toba lies Samosir Island, which arose from the caldera when the magma cap, which had crusted over after the eruption, was pushed up about 1500 meters due to the building pressure from the partial refilling of the magma chamber.  Samosir Island at approximately 630 km²  is about ten times the size of Manhattan¸  or slightly smaller than the entire area of New York City (which is approximately 786 km²).

            Scientists now estimate that the Toba eruption was so intense that it plunged the earth into a six to ten year volcanic winter wherein global temperatures dropped by 3-3.5 degrees with a subsequent cooling episode that lasted up to one thousand years.  Some scientists believe that this single event may have created a bottleneck in human evolution which reduced the human population to somewhere between three and ten thousand people.  They base this hypothesis on genetic evidence that suggests all humans alive today are descended from a small population between one thousand and ten thousand pairs of people about seventy thousand years ago.  Some scientists conjecture that the immediate effects of the Toba explosion, felt over the first couple of years, plus the subsequent ten year volcanic winter, caused massive deaths of human populations across the world.  The majority of survivors of homo sapiens were situated in Africa.  And most scientists agree that this population of homo sapiens  journeyed out of Africa to Europe, Asia and the eventually the Americas  sometime between 75 and 50 thousand years ago.  But there is still a lot of debate over this theory, and there is evidence that local people survived this cataclysmic event.

            At the time of the explosion there were several variants of hominid living on this earth:  homo erectus, homo sapiens neanderthalis,  homo sapiens sapiens, and possibly also the recently discovered homo denisova and homo florensiensis.  Also at the time of the eruption, there were undoubtedly people living throughout Sumatra, Java and Malaysia.  Recall that the first discovered evidence of Homo erectus was that of Homo erectus erectus, aka Java Man, discovered in 1891 near  the city of Solo on the island of Java.  About thirty years after the discovery of Java Man, Solo Man was found.  Whereas most other subspecies of Homo erectus died out before or about the time of the Toba eruption, Homo erectus soloensis aka Solo Man may have persisted until as recently as 50,000 years ago.    Java Man dates back to about 1.8 million years ago.  But Solo Man lived on the island of Java between 1.6 million years ago until about 50,000 years ago, and that would mean that Solo Man survived the Toba eruption. 

            An additional possible local survivor of the Toba explosion may have been Homo Florensiensis aka Flores Man or nicknamed the hobbit because of their small stature.  However, it is still being debated as to whether Flores Man is indeed a whole new species or merely a small pool of  mutated homo erectus.  Nevertheless, although the skeletal remains discovered date from 38,000 to 13,000 years ago, tools and implements attributed to them date to between 95,000 to 13,000 years ago.  Thus, the hobbit may also have  been around at the time of, and therefore survived, the Toba explosion.  However, as far as I know, there is no fossil record of the hobbit living that long ago, only circumstantial evidence of their existence through the dating of tools.

            Varients of homo sapiens date back to almost 250,000 years ago, thus we know that homo sapiens were also living at the time of the Toba explosion.  And recently scientists have found genetic evidence of interbreeding between homo sapiens and homo erectus dating to about 75,000 years ago or at the time of the Toba event.

            The Denisova hominin like the florensiensis hominin is a very interesting recent discovery, and it’s characterization as a separate hominin species is the result of genetic testing on a small finger bone and tooth discovered in 2008 in the Altai Mountains of Siberia.  Human artifacts discovered at the same level at that site were carbon dated at 40,000 years ago, thus indicating that denisova also survived the Toba event.  From the mitochondrial sequence, the Denisova population along with Neanderthal shared a common branch from the lineage leading to modern African humans. 

You have to love the new science of genetic anthropology, which is quickly replacing theoretical quantum physics as the most incomprehensible of sciences, but scientists now  believe that based on mitochondrial sequence found in this denisovan tooth, and certain neanderthal remains, the Denisova population along with

Neanderthal shared a common branch from the lineage leading towards modern African humans, but that the denisovans and the neanderthals began to diverge approximately 640,000 years ago.  The denisova therefore would have lived from 640,000 years ago until at least 40,000 years ago.  Thus, both homo erectus and homo denisova survived the Toba explosion (at least to some extent) and interbred with homo sapiens.  Scientists believe there is genetic evidence that Melanesians’ prehistoric ancestors interbred with the Denisova hominin, sharing 4%–6% of their genome with this ancient human species.  This would indicate that the denisova ranged widely over the area of southeast asia.

According to the Out of Africa model modern H. sapiens evolved in Africa 200,000 years ago. Homo sapiens then began migrating from Africa sometime after the Toba event and eventually replaced existing hominid species in Europe and Asia.   After analyzing genealogy trees constructed using 133 types of Mitochondrial DNA (mtDNA), researchers concluded that all lines of people examined were descended from a woman from Africa, dubbed Mitochondrial Eve. The Out of Africa theory is also supported by the fact that mitochondrial genetic diversity is highest among African populations.  This would make sense if a smaller percentage of people (i.e. a small genetic diversity) left Africa than those who stayed put.

There are differing theories on whether there was a single exodus or several over time.  A multiple dispersal model involves the Southern Dispersal theory, which has gained support in recent years from genetic, linguistic and archaeological evidence. In this theory, there was a coastal dispersal of modern humans from the Horn of Africa around 70,000 years ago. This group helped to populate Southeast Asia and Oceania, explaining the discovery of early human sites in these areas much earlier than those in the middle east, Europe or Asia.  A second wave of humans then dispersed across the Sinai peninsula into Asia, resulting in the bulk of human population for Eurasia. This second group possessed a more sophisticated tool technology and was less dependent on coastal food sources than the original group.  However, the multiple dispersal model is contradicted by studies indicating that the populations of Eurasia and the populations of Southeast Asia and Oceania are all descended from the same mitochondrial DNA lineages, which support a single migration out of Africa that gave rise to all non-African populations.  However, everything is still open to interpretation and new discovery, for scientists believe that Melanesians  who ranged from the Papua Islands to the Solomon Islands  have little genetic relationship to  Polynesians.  However, as previously noted, modern Papuans, who are descendents of Melanesians also share a small percentage of the denisovan genome.  Melanesians then probably travelled across Asia to the Pacific Islands.  If it was all one people and one migration, one would expect to see some of the denovian gene in the Polynesian people also.

            Thus Toba can be thought of as the destroyer and the creator.  It was essentially a super huge cauldron which cooked up a magical brew embodying both good and evil whose smoke and fumes cast a smell over the entire earth transforming the fate and nature of all mankind. (You might note that Miles and I have been reading a lot of fantasy literature lately- you know, wizards, giants, ancient gods.) This idea plays so well into our archetypal myths of birth, death and re-birth through fire and water, which are re-told so many times in so many different variations by so many different people over so many different ages.  Concomitant with the theme of birth, death and re-birth through fire and water (Venus rising from the water, Noah surviving the flood, Jay Gatsby emerging from the waters of Long Island Sound) are the stories, told all over the world, of man encountering giants, dwarfs, and other manlike creatures with power and/or knowledge either greater or lesser than man’s. 

Carl Jung wrote of a collective unconscious of man which dealt with certain universal archetypes.  Joseph Campbell further developed the theory based on archeological and anthropolical evidence in his Masks of God series.  What I find fascinating with all of this is the idea that this single event, the cataclysmic Toba event, may have caused this clash of peoples, and that early modern man came into contact with other pre-historic man of a different character and nature:  i.e. a clash of man and giants, man and hobbits, man and dwarfs.  Did Toba destroy the old ways and blast man into the modern era, thereby creating the seed of our collective imagination and set forth the events which would be the basis for all stories thereafter told?  Is the Odyssey (which Miles and I just finished reading), the Ramayana (which we view in bits and pieces through wayan puppet shows), the Epic of Gilgamesh, the story of Beowulf, and of course Harry Potter just a retelling of our ancient primordial memories of our clashes with other hominids?  Did Toba brew the coffee that kick started the morning of modern mankind?

            With that in mind, I felt that I could not pass up the opportunity of diving down into the waters of Lake Toba.  When I emerged would I be the same person, or would I be reborn as something new?  Would the universe I encountered after breaking through the surface of these primeval waters be different from the one I had dove from?  I was ready and anxious to meet the challenge.  And so early the following morning after our afternoon arrival on Lake Samosir, I got up from the our hotel room, went down to the rocky pier extending into the Lake and dove into the dark cool waters.  I swam for about a half a mile towards the middle of the lake and the mouth of an inlet.  I dove down into the depths for as long as my ears would permit.  It was cool, refreshing, and but for a small entanglement with a storm tossed fishing net, completely uneventful.   When I emerged nothing had changed.  I could still see the hotel, the small fishing boats, the dock where the ferries were tied up.  When I checked, I was still the same old (figuratively speaking of course) me.  But, hey, who knows?  The Toba event did not happen over night.  Its direct effects lasted for a decade and its indirect effects (the migration of modern man from Africa) lasted tens of thousands of years.  Maybe it will grow on me (I did notice some new ear hair- a sure sign of my primordial ancestry- but thank god for the gift of fire which lead to the bronze age, the iron age, the steel age, and last but not least- tweezers).  In any event, although I detected no instantaneous results, I figured that I had to give Miles the opportunity for such re-birth and transformation, so later the two of us again went swimming in this magnificent Lake.  We had a blast.