Re: Evolving radiation resistance

[Kai Kaletsch <eic@shaw.ca>]

Andy wrote:



> One thing to remember about evolution is that it only works if organisms

> die before they can reproduce.



Actually, evolution works even after conceiving or giving birth. It helps if

your offspring survives to have kids of their own! That is where older

members of the extended family can be useful. They can use their wisdom to

help the group prosper and they can help raise a third generation, while the

second (physically strong) generation is working or hunting.



On the other hand, we have to realize that extreme longevity is not a

universal evolutionary advantage. If it were so, we would all live to be

10000 years old. For evolution to work, new generations have to be born,

which means resources have to be freed up, which means someone has to die.



One thing that was probably a strong evolutionary advantage to primitive

societies was to go from being a productive member of the group to being

dead in a short time, rather than being a burden to the group for decades.

It may well be that evolution has programmed certain diseases into us to

accomplish that.



I don't think that it is likely that evolution would result in a local

population being more radiation resistant than others. How a cell reacts to

a radiation induced injury is a very basic function and would have been

influenced by billions of years of evolution. There are probably not many

groups of people that have remained in the same locations for more than a

few thousand years.



Kai





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

From: "A Karam" <paksbi@rit.edu>

To: <radsafe@list.vanderbilt.edu>

Sent: Thursday, September 02, 2004 12:15 PM

Subject: Evolving radiation resistance





> One thing to remember about evolution is that it only works if organisms

> die before they can reproduce.  Natural background radiation levels,

> even in Kerala or Ramsar, are not likely to cause death from cancer when

> a person is in their teens or 20s.

>

> We should also remember that natural background radiation is responsible

> for only a few percent of spontaneous DNA damage.  This means, again,

> that even a dramatic increase in background radiation levels will not

> contribute markedly to additional DNA damage and is therefore unlikely

> to cause a marked increase in carcinogenesis.

>

> Accordingly, it seems unlikely that living in these areas would

> contribute any selection pressure towards developing a resistance to

> radiation at these levels.

>

> Sorry....

>

> Andy

>

> P. Andrew Karam, Ph.D., CHP

> Research Assistant Professor

> Rochester Institute of Technology

> Department of Biological Sciences

> 85 Lomb Memorial Drive

> Rochester, NY  14623

> +1 585-475-6432

> karam@mail.rit.edu

>

> "If A is success in life, then A equals X plus Y plus Z. Work is X; Y is

> play; and Z is keeping your mouth shut." - Albert Einstein

>

>

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

>

> One factor that I have not seen discussed in the hormesis debate is

> natural

> selection. Since man has for ever been exposed to natural radiation, is

> it

> not reasonable to assume that natural selection has reinforced our

> resistance to any deleterious effects? Is it possible that the native

> population of Kerala, for instance, has a greater resistance to

> radiation

> than areas with low natural radiation?

>

> My personal (uneducated!) feeling is that reasonable levels of natural

> radiation (and occupational exposures to similar types and energies of

> radiation) is something the human organism (and all other terrestrial

> organisms) has adapted to. And that, as Dale states, the confounding

> factors are so numerous (and over-riding) that confirmation, or

> otherwise,

> is extremely difficult.

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