Scientists will outline dramatic evidence this week that suggests a comet exploded over the Earth nearly 13,000 years ago, creating a hail of fireballs that set fire to most of the northern hemisphere.
Primitive Stone Age cultures were destroyed and populations of mammoths and other large land animals, such as the mastodon, were wiped out. The blast also caused a major bout of climatic cooling that lasted 1,000 years and seriously disrupted the development of the early human civilisations that were emerging in Europe and Asia.
'The magnitude of this discovery is so important,' team member James Kennett, of the University of California, Santa Barbara, told the journal. 'It explains three of the highest-debated controversies of recent decades.'
These are the sudden disappearance of the first Stone Age people of America, the disappearance of mammoths throughout much of Europe and America and the sudden cooling of the planet, an event known as the Younger-Dryas period. Various theories have been put forward to explain these occurrences, but now scientists believe they have found a common cause in a comet crash. However, the idea is still controversial and the theory is bedevilled by problems in obtaining accurate dates for the different events.