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RE: " we're evolved for radiation " - geophysicist on pole revers als



Jaro,

Thanks for putting a "date" on the last magnetic field reversal.  I always

assumed that the atmosphere was the source of shielding for life on earth..

That is why any life on Mars would be primitive at best, and why single cell

creatures were the only life form on Earth for so long..



-- John 

John Jacobus, MS

Certified Health Physicist

3050 Traymore Lane

Bowie, MD  20715-2024



E-mail:  jenday1@email.msn.com (H)      



-----Original Message-----

From: Franta, Jaroslav [mailto:frantaj@AECL.CA]

Sent: Monday, November 04, 2002 10:11 AM

To: 'John Jacobus'; RADSAFE

Subject: RE: " we're evolved for radiation " - geophysicist on pole revers

als



-----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 

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