Re: DINOSAUR CANCER

[Thomas_R_HOLTZ@umail.umd.edu (th81)]

>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.


Oh, bloody hell, here we go again...

When discussing this topic with a friend who is into serious supernovae
studies, he pointed out that, although the neutrino flux on a planet close
to a supernova is sufficiently high to kill, any planet close enough to be
subjected to that level of bombardment would also be obliterated by later
effects of the blast.  Given that the Earth is still here, we still have a
crust, and life persists, a neutrino bombardment doesn't seem a likely cause.

Cosmic rays, though, might still apply.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084