Re: " we're evolved for radiation " - geophysicist on pole reversals

[Muckerheide <muckerheide@attbi.com>]

on 11/4/02 1:56 PM, Jacobus, John (NIH/OD/ORS) at jacobusj@ors.od.nih.gov

wrote:



> Jaro,

> My comments are based on my disbelief that the magnetic field of the earth

> has any influence of the radiation we receive from space,



How do you "disbelieve" a plain physics fact!?  (It's not even biology!)



Regards, Jim



>whether it is

> ionizing or UV.  I was wonder why the comment was made "we're evolved for

> radiation" in the context of the article.

> By the way, I believe that Mars lacks a magnetic field.  Of course, we do

> not know if life exist there, so maybe a magnetic field is necessary.

> -- 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 12:36 PM

> To: Radsafe (E-mail)

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

> als

> 

> 

> -----Original Message-----

> From: Jacobus, John (NIH/OD/ORS) [mailto:jacobusj@ors.od.nih.gov]

> Sent: Monday November 04, 2002 11:37 AM

> To: RADSAFE 

> Subject: 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 

> 

> 

> Sorry, but I don't follow your reasoning.

> Over millions of years, the main agent of the mutations responsible for

> biological evolution is radiation (the last polarity flip was less than a

> million years ago).

> So life is liable to remain primitive in the absence of radiation, not its

> presence ("we wouldn't be here if it weren't for radiation").

> What the atmosphere shields us from is UV radiation, mainly by the ozone

> component. 

> The atmosphere of Mars is very thin and lacks the UV-protective ozone layer,

> thus killing any life on the surface.

> However, according to some estimates, even on the Earth, most of the total

> biomass of the planet resides underground - including deep underground, up

> to several kilometers - in the form of single-celled thermophilic life

> forms. That those haven't evolved (much, except for the amazing radiodurans

> bacteria) is something of a curiosity, because over long periods (thousands

> of years, when in the dormant state) they will get a huge cumulative dose

> from geological NORMs.

> I haven't seen any data on Martian polarity reversals. Much more surface

> exploration will have to be done before such data is obtained (may not exist

> if Mars has no plate tectonics), or information about possible subsurface

> microbial life. It is known however, that early in its history Mars had

> large oceans of water, similar to the earth.

> There is also a high probability (read certainty) that even if indigenous

> life did not evolve on Mars, microbial life from earth would have

> contaminated its neighbour by way of meteoritic impact ejecta transfer (and

> vice-versa, from Mars to Earth - we could be descendants of Martians :-).

> Why were single cell creatures the only life form on Earth for so long ?

> Good question. But I don't see an answer in any of the above. I believe that

> current exobilogical theory holds that its just a matter of extremely low

> probability for evolving multicellular life.

> Jaro 

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