Around 70,000 years ago, the Toba Supervolcano erupted where we would now find Indonesia. Once the eruption had occurred, the ground collapsed, leaving behind an indentation know as a caldera (see figure 6.1). As a result of this eruption, there was a winter that lasted for around 7 years, and afterwards, there was a 1000 year cooling period. This significant historical event is known as one that vasty affected the globe (Krulwich, R. (2012, October 12))
Not only did this eruption occur around 70,000 years ago, but it has been determined that at around this time, there was a vast genetic bottleneck effect on the human population. It has been proposed, through genetic analysis, that around 10,000 of the Homo sapien species inhabited the Earth at this time. This vast reduction in population resulted in a smaller potential gene pool and hence, less differentiation in the Homo sapien population today.
Presently, it is preferably believed that the genetic bottle neck was due to the eruption of the Toba Supervolcano, however, recently discovered evidence can provide a different viewpoint.
Point of View ONE: Supervolcano to blame for humanities near extinction
It is believed that as a result of the cataclysmic eruption of Toba nearly drove humanity to the point of extinction. A super volcano is capable of spewing out thousands of times more magma then the every day volcano and has the ability to blot out the sun with ash, reflecting its rays and cooling the Earth. This effect is known as a volcanic winter as the atmospheric temperature is reduced drastically. It is known that around 70,000 years ago, the Earth experienced a rapid climate change, where the Earth was encompassed by an enduring winter (Krulwich, R. (2012, October 12)). It is believed that this reduction in temperatures a rapid change in environments resulted in the almost extinction of the Homo genus. This massive environmental change is predicted to have resulted in a population bottleneck of various species of human and other animals at the time. This bottleneck in turn, resulted in an acceleration of the natural differentiation of isolated human populations. This isolation and devastation is believed to have eventually lead to the extinction of all Homo species except for the branch that eventually gave rise to the modern humans.
Point of View TWO: Supervolcano not to blame for the near extinction of humanity
Recent research, conducted by geologist Christine Lane of the University of Oxford, suggests that the super volcanic eruption may not have caused the almost extinction of the humanity ((Lane. 2013, April 29) For instance, prehistoric artefacts collected from India and dating back to after the eruption suggests that people coped well with the affects of the eruption compared to what was previously thought. Furthermore, it has now been proven that the cataclysmic winter that was invoked as a result of the eruption did not cause a volcanic winter over East Africa, where Homo sapiens thrived. Through her investigations, Christine Lane and her peers examined ash from the Toba eruption that was extracted from Lake Malawi, one of the largest lakes in East Africa. Lane and her colleagues have positively identified the ash as from Toba, however, through their discovery, they two found that the ash travelled twice the distance as to what they previously believed and that there was also more ash found in Malawi then what was expected. As it is commonly believed, the eruption caused many living matter to die off, and to support this theory, it would be expected that in the same layers as the ash found in the Lake Malawi, Lane would discover algae and organic matter that would indicate a significant temperature drop in East Africa. But this was not found. Lane said that 'the environment very quickly recovered form any atmospheric disturbance that may have occurred,' as the organic matter did not suggest a mass affect on living matter as a result of the eruption (Lane (2013, April 29) Due to these revelations, other catastrophes are up for consideration, as disease too could have played a role in the mass population bottleneck.
Although this new found evidence can lead to the assumption that the global climatic impact was not as dramatic to cause a vast reduction in population, to further prove this hypothesis, evidence from other ash locations would have to be tested to determine whether the account is accurate.
How did we actually survive either interpretation of the event?
As presently there are conflicting stories regarding whether the eruption of the super volcano Toba caused a mass execution of the Homo genus, there are also many ways in which can be analysed as to how the genus survived. As previously stated, biological, cultural and technological evolution all play a key role in the evolution of the modern Homo sapien. And to analyse how we survived, we have to discuss the way in which our evolutionary path aided in our survival.
As it has been determined through fossil evidence, the brain case of the Homo genus has increased throughout time, allowing for advanced cognitive function and decision making skills. This adaptation alone would have allowed the Homo genus to adapt to a changing environment and circumstances as they would be able to communicate and decipher the correct action to take in such a time. Furthermore, the advancement of the brain allowed for the ability for individuals to communicate through teaching and art. These techniques would allow for cultural evolution, but also knowledge being passed through entire populations as to how to proceed.
Not only did biological factors aid in the Homo genus' survival, the evolution of technology could have aided in our survival. The ability to hunt had also adapted through time and accompanied by the advancement in communication, those in threat would still be able to hunt for food sources as a group. The adaption of using tools to hunt made hunting an easier process and ensured food sources for a population as a population would effectively be able to find food in dire situations. The communication, as earlier stated, was also key as it allowed for cooperation in finding larger food sources.
The technological advancement of using fire to cook and keep warm would have aided in the survival of the Homo genus as although there was predicted to be a drastic cold climate change, fire would have allowed for individuals to remain warmer than if fire was not present.
Lastly, if we were to analyse using the knowledge of natural selection and discuss the mass climate change as a selection pressure that acted on the Homo genus, it can be said that through genetic variation, certain individuals were selected for and went on to breed after the drastic change in whether where others were selected against. This example of a bottleneck can allow for the assumption that the certain individuals that survived to continue breeding had favourable phenotypic characteristics such as larger builds and more advanced brain function to allow for their survival.
There are many ways in which fossil evidence and evolutionary adaptions aided in the survival of the Homo genus after a catastrophic change in climate, however, as it is still undetermined what caused the death of many individuals 70,000 years ago, it is still difficult to pinpoint what allowed for our survival.
Figure 6.1 above: Q. Choi, B. (2013, April 29). Supervolcano Not to Blame for Humanity's Near-Extinction. Retrieved September 21, 2015, from http://www.livescience.com/29130-toba-supervolcano-effects.html