New Scientist 15 Dec 2001, page 10

"...life on Earth may have been repeatedly disrupted by bursts of gamma rays from space. The bursts would have disturbed the Earth's atmosphere, exposing organisms to high levels of mutagenic radiation"

The scientists believe the bursts only reach Earth once every 5 million years (it was previously thought never) and degrade the atmosphere, exposing organisms to UV radiation (and cosmic rays, I presume, which the atmosphere also protects us from).

"The impact of gamma-ray bursts has not been widely discussed, nor do biologists, including myself, have much information about their frequency or exposure levels" - admits scientist Mitch Sogin.

Similar research reported at Space Daily

A BBC report of an archaeological site off India's western coast that may be up to 9,000 years old. Acoustic images from the sea-bed suggested the presence of built-up structures resembling the ancient Harappan civilisation, which only dates back around 4,000 years.

More at Times of India and BBC again

Feb 2002 articles at Earthfiles (Linda Moulton Howe) and Arabia.com