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Is it true about the low radiation = no evolution?

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Sofiab In this book it's explained that on a planet with little UV radiation there will be no evolution because mutations will not happen.

Is this true? I haven't though about gene mutation being solely due to UV radiation. They could happen for other reasons right?
If nothing else there would be some nuclear radiation I presume.

John-Alan Yup, as you point out nuclear radiation also causes mutation. In addition, mutations can be caused by errors that occur during the replication of DNA and by the by-products of biochemical reactions going on in the cell.

In short, having little UV-radiation might slow down the rate of mutations occurring a little bit, but it wouldn't have much effect.

Of course at the time Starship Troopers was written much less was known about the mechanics of genetic mutation and DNA, than is known now.

Kirk Mutations are also caused by gene swapping using phages as the carrier.

I believe alpha particle radiation is much more likely to damage a cell's genome than betas or photons such as UV, but only when the radioactive substance is consumed. One current source of such alpha radiation is from the traces of polonium found in tobacco.

Johnny Stone I'm not a geneticist nor a nuclear physicist, but I did go through the U.S Army's Nuclear, Biological and Chemical Warfare School. From my understanding radiation in any form, regardless of the exposure venue, does nothing but corrupt and kill.

I've never believed in the concept of mutation through radiation exposure- it makes for nice story ideas and good movies, but in reality I need to see to believe.

John-Alan Johnny wrote: "I'm not a geneticist nor a nuclear physicist, but I did go through the U.S Army's Nuclear, Biological and Chemical Warfare School. From my understanding radiation in any form, regardless of the exp..."

But the way radiation kills is exactly the way it causes mutation. Yes, at very high doses it basically blasts all your cells to shreds. However at lower doses it just damages your DNA, either directly, or by blasting apart water molecules in your cells, which then become free radicals and react with your DNA. If this damage is too great, or in the wrong spot, you can end up with cancer, but otherwise you might just end up with slightly different genes to pass to your offspring.

Yes, 'mutation' as usually shown in the movies is nonsense. Radiation won't suddenly result in flies the size of an elephant or something like that.

However in the scientific sense of the word mutation just means a single change to one of the base pairs in a gene (i.e. changing one of the 'letters' in the 'word' that is spelled out by the gene) and that most definitely can be caused by radiation, either directly or by necessitating a repair, which then introduces an error.

Johnny Stone Hey John,
lol You lost me with that first paragraph, and I don't have the knowledge to debate it.
Maybe it will help if i explain it from my pov in laymen's terms the way I learned it in school, or at least remember it.

When you are exposed to, lets say a nuclear blast, your body is shredded like being hit with an invisible shotgun blast of gamma radiation- the exact does of radiation you receive, as you said, is determined by distance and protection.

Now, the human body is able to safely purge 'X' amount of radiation on a natural basis over time- we are exposed to it daily in fact- and I don't see human's or anything else for that matter 'mutating' as many people would like to believe.
For those of us that were on the Radiological Monitoring and Servery teams, we had a Turn Back Dose Rate of 100 Rads. By the book, we should be okay, but those effects are cumulative no different then what we are exposed to in daily life. In a nuclear blast we're talking 10,000+ Rads, tapering off with distance.

If you are hit by one molecule of Gamma radiation, it blast a hole through your body irradiating every cell it comes in contact with, killing it. This irradiated cell now passes that radiation on to every cell it is in contact with and so on until it's spent it's stored energy. 1 Rad or 10,000 the effect is the same- it spreads and kills. Whether you survive or not is determined by dosage. If you do, my guess is you'll probably end up with cancer since now you have collective masses of dead cells scattered throughout your body.

Alpha Radiation is even nastier, IMO. Breath in a radiated particles of dust and they comes to rest in your lungs... Good luck.

I'm not in a position to really argue this one way or another, but I was taught differently. I'm by no means an expert in the possible genetic effects, but I do know what the battle field effects are on people and equipment exposed to this sort of thing.

CD Johnny wrote: "Hey John,
lol You lost me with that first paragraph, and I don't have the knowledge to debate it.
Maybe it will help if i explain it from my pov in laymen's terms the way I learned it in school, o..."

You understand that UV causes skin cancer? That is the reason tanning machines are now restricted in use for people under 18 and waivers are required in many of the states in the US for any user.

Cancer is a mutation of the normal growth and mitosis process of cells. In the cases of various forms of whether carcinoma or melanomas to enumerate two, damage to the cells from UV is a primary factor. This is either from excess exposure or long term accumulated damage.

See ->

It is the long term, very low dose/exposure to Ultraviolet Radiation that is referred to regarding the evolutionary process. There are other factors that also drive evolution so a lack of UV alone may not stop the changes. UV does play an interesting role however at the cellular level such that single cell organisms are far more prone to its effect.

On a related topic, the military was educating soldiers to believe that there was/is a 'safe' level. At 1-2 grays/sieverts (the newer and Internationally accepted dose/absorption units) which is roughly equivalent to 100-200 rads, a human is going to be very sick. They should survive . . . statistically. The military was keenly aware after the early 1950's that much more of a single exposure and the personnel wouldn't even be able to report back with their test equipment. They'd be left on the battlefield for fear of contaminating other personnel.

Gamma radiation is not molecular/particle in nature.

A nuclear blast; I'm not initially terribly worried about much beyond the the heat and blast zone. If I've survived that and am not dead with a few hours or less from a huge dose of wave radiation, there's a bunch of other things that are of greater concern. 4-5 sieverts of exposure for more than a handful of people (there aren't facilities to even begin to treat more than that) and I'm probably dead within weeks from some form of infection or systemic cancer like AML if I do get hit by ionizing radiation like Gamma radiation.

Or in the words of some modern seers -

"the future is so bright,
I gotta wear Shades . . .

message 8: by Phil (last edited May 14, 2014 06:24PM) (new) - rated it 4 stars

Phil Johnny, it's all a matter of degrees. You're being hit by radiation all the time but it's not a big deal. In fact there is a theory called radiation hormesis (or homeostasis) that maintains that low levels of radiation are good for you because they stimulate the repair mechanisms of your cells and make them stronger.
Gamma radiation may damage a cell or pass right through but it won't make a cell radioactive. Basically your fourth paragraph above is completely wrong in every way. I'm not trying to put you down, just clear up some misconceptions.
I'm a nuclear medicine technologist and every day, in our department, we inject dozens of patients with radioactive pharmaceuticals so we can scan them for a variety of things like heart disease and cancer. We wouldn't do it if there was significant risk to the patient.

You're right that alpha and beta radiation is more damaging than but they also don't travel very far before they hit something so the damage is pretty localized.
In the 30 years I've been doing my job I been exposed to much more radiation than the average person and my coworkers and I don't seem to have any higher incidence of cancer or other diseases than other people.

Johnny Stone Very enlightening on all points, and I won't say that I'm not wrong in some sense- things start to fade over time and it has been almost 20 years since I've cracked a book on the matter and most of you seem much more educated on related subject matter outside of battlefield application than I am.
And yes, I do realize that radiation is not a particulate traveling at the speed of light- I was simply trying to paint a picture in the minds eye.

Guess it really boils down to the definition of what a mutation is, but unless I'm mistaken (sorry for derailing the thread in this case) the major point is not UV radiation and skin cancer, but the effect of low level radiation on the human body from an evolutionary standpoint.

That, from what I gather is theory, and yet to be proven.
Are we trying to say that if I get cancer from environmental exposure will that be passed on to my offspring or will it alter me on a genetic level? I think not.

Prospectavebooks The idea of radiation causing mutation seems logical, but when you consider that you cannot pass on a change to your DNA that occurs in your arm, say, to your descendants, it seems so very unlikely. To be passed on, a change in your DNA caused by radiation (or some other source) must occur in either the pre-fertilization sperm cell or ovum, or else in the fertilized cell before it has undergone its first mitosis (splitting). That would be a spontaneous mutation, and in almost 100% of cases would either provide no survival advantage, or would cause early fetus death. Favorable mutations, by definition, occur so seldom that hundreds of thousands of years can go by without any occurring.

The low mutation rate of Sanctuary was not important to the story, so Heinlein seems to have simply mentioned the subject so as to have some nice hard science in the story. Hard Science SF writers are like that.

John-Alan I think some of the misunderstanding seems to be surrounding the word 'mutation'. Hollywood has painted us this picture of 'mutations' causing weird monsters and the like, but in biology, all mutation means is a change to a certain gene.

Let me explain further. As you are probably aware the DNA in our cells contains all our genetic information. This information is stored by the way the DNA molecule is built up. If you think of the famous double helix picture, and then think of the 'crossbars' connecting the two strands of the helix, those crossbars can be made of one of four chemicals. I forget those exact names, but they are usually shortened to A, C, G, and T. The pattern in which those chemicals occur stores the genetic information. Just like in language we can use patterns made from 26 (in English) letters to form words, so our bodies use patterns of those 4 'letters' to form 'words', which we call genes. Those genes control a certain aspect of the body (e.g. the colour of your eyes).

So if for example your eye-colour gene is: AGGTCA then you might have blue eyes (real life is more complicated than this). Now if for some reason that gene is changed to read AGGTCC then you have a mutation in your eye-colour gene; it has changed.

What makes this a bit more complex is that every cell within your body contains this gene, even if that cell has nothing to do with your eyes. Thus in most cases it won't matter if the eye-colour gene in a random cell is mutated.

Now if a mutation occurs in genetic matter that you will be passing on to your offspring (i.e. sperm or egg cells) then that might cause your offspring to be (more) different from you. The higher the rate of mutation, the more chance your offspring will inherit a mutated version of one of your genes. While UV radiation could certainly cause mutations, especially in something like bacteria, which have less protection, it is not really the most significant source of them (at least to my understanding).

On to the radiation / cancer / mutation link:

Nuclear radiation generally comes in three flavours: alpha, beta and gamma. Alpha radiation consists of particles composed of two protons and two electrons. It can be stopped by a thin sheet of paper, or by the layer of dead skin cells on top of your skin. Thus it is only really dangerous if you ingest or inhale some substance that is emitting alpha particles.
Beta radiation consists of elections.
Gamma radiation consists of photons, just like UV and regular ('visible') light. However the photons in gamma radiation have a lot more energy than those in visible light. UV light has less energy than gamma rays, but more than visible light.
Visible light is also a form of radiation, but is in principle not harmful. The harmful types of radiation are usually referred to as ionising radiation, this includes nuclear radiation, but e.g. also X-rays.

Whatever the source of ionising radiation, the way they damage you is as follows: whenever a particle or photon of radiation travels through your body, there is a chance it may hit one of the molecules that make up your cells. It may hit your DNA directly, but usually it will hit a water molecule (simply because there are more of those). It will then interact with the water molecule and break it into fragments, called free radicals. Free radicals are very reactive and will try to react with the nearest available atom or molecule. If that is your DNA, then the free radical will react with some of the atoms in the DNA, damaging the DNA. Your body is able to repair this damage, but only to a certain point. Also the repair is not perfect, sometimes the repair comes out wrong and one of the 'letters' in a gene is swapped. In other words, your DNA repair mechanism can cause mutations.
If you are exposed to a lot of radiation in one go then your repair mechanisms can't cope and some/many/all (depending on dose) of your cells are so damaged that they die. This is the cause of radiation sickness.
If you receive a lower level of radiation then your cells don't die, but they will probably sustain mutations. In most cases this won't matter, e.g. if a cell in your liver has a mutated eye-colour gene that won't do much. However if a mutation occurs in one of the genes that control cell growth, then that cell may (either right away, or after some time, cancer is complicated like that) start growing and replicating itself uncontrollably, which is what cancer is.

Tl;dr: A mutation is a change to a certain gene in a certain cell, nothing more, nothing less. In most cases this is harmless. In some cases it may change the genes offspring receive. In some cases the mutation may cause a cell to become cancerous.

Johnny Stone I have a question regarding the mutation aspect.

I understand the concept of a mutation being anything outside of the standard, or established norm. Now if we look at this idea in regards to human evolution, and what I gather from the above post, are we saying that all of us are in sense mutants? For example, the genetic material passed down to me says green and brown eyes, yet mine come out some other color for whatever reason deviating from the norm. Does that make it a make it a mutation? (I'm not trying to be be a smart ass here, simply understand a concept far beyond my level of schooling)

If that is the case, there had to be some initial standard of genetic material, a ' pure human' at one time, and all of us since that time are mutations, correct? So are what we consider birth defects or abnormalities in human development in fact mutations of their own?
I know this is a very black and white, simplistic view, so bear with me.

Ian Johnny, not trying to be patronising but you probably need to get a better handle on evolution and how it works before you can answer your question. Richard Dawkins is very readable - The Ancestor's Tale would fit the bill quite nicely.
In effect everything is a "mutant", bear in mind that all the species originally sprang from single celled organisms and the little changes have added up to give us the diversity we have today. There is no such thing as a "model" human (or dog, or cactus, or whatever) we are all variations. Species have a degree of stability until something works better and eventually replaces what went before.
Those little changes are what drive evolution and Heinlein's hypothesis was that a higher level of radiation would drive more changes, so you get more throws in the evolutionary crap shoot. I've personally not seen any research that proves that one way or another. It certainly wouldn't have been an unreasonable view at the time.

John-Alan Johnny wrote: "are we saying that all of us are in some sense mutatants"

Correct. However mutation doesn't mean deviation from some kind of norm, it merely means a change. Usually people take the parent organism as the baseline and then say the genes of the offspring contain a mutation if they're different.

However if I were to give you two pieces of DNA and didn't tell you which came from the offspring and which from the parent you probably wouldn't be able to say which was which. All you could say would be that the two pieces of DNA are different, but you wouldn't be able to label one the 'baseline' and the other the 'mutatant'. In other words, it's just as valid to say that to get from DNA A to DNA B you need a mutation in spot XYZ as it is to say that to get from DNA B to DNA A you need a mutation in spot XYZ.

Johnny Stone Ian wrote: "Johnny, not trying to be patronising but you probably need to get a better handle on evolution and how it works before you can answer your question. Richard Dawkins is very readable - The Ancestor'..."

To be honest, I've never been much a supporter of evolution- too many loopholes as I see it- and my primary areas of interest and study lay in other subjects.

Interesting discussion though, and thank you for taking the time to answer my questions.

message 16: by [deleted user] (new)

Radiation causes mutations, so, it helps evolution, because mutations are basis for evolution. So, I guess that low radiation can mean 'low' evolution, although, I don't think anyone proved it in practice. As a hypothesis, it sound valid.
But that's not the problem here. Man, as a species, don't really evolve like the rest of life. For evolution you need changes in gene pool, but they are insignificant if environment doesn't 'choose' them, by changing itself. Humans aren't dependent of it environment any more. Actually, we aren't dependent of changes of it. In truth, we change the environment, and by that, we stop our own natural selection. In past, when we weren't more that gorillas, when environment drastically changed, just the 'mutants' suvived, because they were better adapted. But, in modern time, environment isn't changing us, we are modeling it by our standards, to meet needs of 'regular' human, so mutations don't really matter.

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