DINOSAUR CANCER

[steve.cole@genie.com]

Cancer may have killed dinosaurs, scientist says
 LONDON, Jan 11 (Reuter) - Cancer caused by particles thrown out by dying
stars may have killed off dinosaurs 65 million years ago, an American scientist
said on Thursday.
 Juan Collar of the University of South Carolina believes that sub-atomic
particles called neutrinos released from stars collapsing in earth's galaxy may
have produced a cancer pandemic among dinosaurs.
 Neutrinos colliding with the nuclei of living atoms could damage DNA,
nature's genetic building blocks, producing cancer-causing mutations.
 Writing in the New Scientist journal, Collar suggests that a collapsing star
within 20 light years of earth could produce about 12 malignant cells per
kilogram (2.2 lb) of living tissue.
 The impact would be greater on larger animals like dinosaurs because they
have more tissue to become cancerous. Because neutrinos are not halted by the
outer layers of the body, the cancers are likely to develop in vulnerable tissue
like bone marrow, Collar said.
 Other scientists have suggested that mass extinctions could be caused by
cosmic rays from supernova explosions, but Collar says these happen too
infrequently to explain the disappearance of the dinosaurs.
 Star collapses, when a star caves in under the weight of its own gravity,
occur within 20 light years of earth about every 100 million years.