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Exploding Supervolcanoes Changed our DNA

We did not have millions of years to differentiate genetically

Jul 8, 2009 08:44 GMT  ·  By
The Toba supervolcano erruption brough forth almost a decade of volcanic winter, which erased a large part of our ancestors' population
   The Toba supervolcano erruption brough forth almost a decade of volcanic winter, which erased a large part of our ancestors' population

Despite the fact that science has proven we descended from the same common ancestor as primates did millions of years ago, it's a known fact that most humans today have a remarkably similar DNA, a fact that until now raised questions as to how we failed to diversify among ourselves more. Some researchers have proposed that the catastrophe that followed the eruption of the Toba supervolcano, in what is now Sumatra, some 74,000 years ago, is the main culprit for this. It may be that the devastation that came after the unimaginable eruption was responsible for reducing the hominid population to just a few hundred thousand individuals altogether.

While investigating the human DNA, geneticists arrived at the conclusion that a massive die-off of humans must have occurred between 90,000 and 60,000 years ago, a time frame that is consistent with the timing of the Toba eruption. The “bottleneck” in human development explains why we still have almost the same genetic make-up – rather than evolving for millions of years, as first thought, we may have only had about 76,000 years to do so. While this may seem like a lot, it's but a wink on the geological time scale, which stretches back billions of years, LiveScience reports.

A favored explanation among scholars has been that the supervolcano's eruption brought forth an Ice Age that led to the development of thick glaciers, which covered the land feeding countless animal and plant species. A massive extinction event occurred, and only few species managed to survive. However, while modeling this scenario in computer simulations, researchers noticed that none of the six versions of the idea that they'd tried led to the onset of a glacial epoch, not even when considering changes in sunlight and planetary chemistry, as well as drops in global temperatures.

However, Rutgers University expert Georgiy Stenchikov and his team noticed that, while no Ice Age ensued, the weather patterns indeed changed, and, in all models, a decade of severe volcanic winter appeared. “The 'volcanic winter' following a supervolcano eruption of the size of Toba today would have devastating consequences for humanity and global ecosystems. These simulations support the theory that the Toba eruption indeed may have contributed to a genetic bottleneck,” the experts wrote in a study published in the latest issue of the Journal of Geophysical Research-Atmospheres.