Science News Review

Supernovae, Comets and Holey Mammoth Tusks

Jan 5 at 11:11pm by Aileen

…a tale of mass extinction and woe

Blue Sky Studios

Not so very long ago the wizened gatekeepers of scientific orthodoxy staged a vigorous and extremely nasty campaign designed to prevent any possibility that impressionable science students or the great unwashed masses might come to suspect that things in our cosmic neighborhood were ever anything but perfectly peaceful, perfectly ordered, and perfectly safe. It was the middle of the 20th century, a bit over 150 years since the staid scientists at the Royal Society in London had discovered the hard way that stones really can fall from the sky despite their pronouncements to the contrary.

Yet the publication of Worlds in Collision in 1950 – and Ages in Chaos in 1952 – purported to demonstrate that the Earth had suffered some serious cosmic upheavals within the memory of human civilizations. These ideas drove such astronomical lions as Harlow Shapley to use every underhanded method and scheme available to destroy the author and reassure the public once again that, despite all evidence and witness through the ages, stones do NOT fall from the sky, comets do NOT wreak havoc on the Earth, and the perfect clockwork of cosmic orderliness is NOT violated by disorderly events. Thus did the notorious Velikovsky Affair take its place in the annals of science’s ample history of internal turf wars.

Many young people today are quite used to the idea that our planet has been bombarded by cosmic billiard balls of one sort or another, learning about the epochal events that marked transitions from one age to another, usually by causing mass extinctions of life forms and altering the course of evolution. Even children’s books and movies portray the catastrophic events of 65 million years ago when a large asteroid ended the age of the dinosaurs. Yet apart from those now-recognized disasters in the distant past of our planet, scientists have tended to remain skeptical of the notion that such world-shattering events have ever occurred – or been recorded – in the short (~100,000 year) history of human beings on this planet.

Archaeologists, geologists and paleontologists do know that there was a mass extinction of megafauna such as wooly mammoths, giant bison, saber-tooth tigers, etc. in North America and Siberia just 13,000 years ago, when early Americans of the Clovis culture were known to hunt these huge mammals. Some scientists believed that they were driven to extinction by a drastic climate change that began the last ice age, others believed those early human hunters had driven their prey to extinction. But over the last few years a new narrative that reads like a fine detective novel has come to the fore, and it begins with the death of a nearby star 41,000 years ago.

In 2005, nuclear scientist Richard Firestone of the Lawrence Berkeley National Laboratory published research findings that linked the extinction of the mammoths with the supernova explosion of a star just 250 light years from Earth. The initial shockwave hit our planet 34,000 years ago, evidenced by tiny impact craters on mammoth tusks from that time, produced by iron-rich grains that bombarded the Earth at 10,000 kilometers per second. More debris from the explosion was said by the researchers to have formed a comet approximately 10 kilometers in diameter, which hit the Earth 13,000 years ago and caused the extinction.

Now another team of scientists led by anthropologist Douglas Kennett also conclude that a comet was responsible for the extinction of North American megafauna, and have even pinpointed the impact site to somewhere close to Chicago. The event caused an ice age along with the extinction of the giant mammals and disappearance of the human culture that relied upon them for sustenance.

There is of course no universal consensus about this theory despite evidence from many scientific fields, but the authors have stated that a collision so recent in human history underscores the importance of trying to detect and deflect cosmic debris that may be coming our way. And, in the end, we do now know that things are not nearly so peaceful and serene in our neck of the galaxy as scientists once assumed.

Links:

Supernova Explosion May Have Caused Mammoth Extinction
Scientists Say Comet Killed Off Mammoths, Saber-Toothed Tigers