-----Original Message-----
From: John Jacobus [mailto:jenday1@MSN.COM]
Sent: Sunday November 03, 2002 9:00 PM
To: RADSAFE
Subject: Re: " we're evolved for radiation " - geophysicist on pole reversals
Jaro,
What is meant by "we're evolved for radiation?" Had humans evolved the last
time it occurred, or was life more primitive?
-- John
Yes, humans were around the last time we had a polarity flip, 780,000 years ago.
But that's besides the point.
Many human environmental adaptations seem to go way back to our primitive ancestral forms, possibly as far back as single-celled organisms (that appears to be the gist of the papers I've read, such as those by Andrew Karam).
All in all, there have been about 1,000 polarity reversals, which are recorded in the earth's crust like magnetic tape (earliest ones in the old crust near subduction zones, latest ones at the mid-oceanic rift zones). During the vast majority of those, only single-celled life existed on the earth.
Jaro