This makes me wonder what effect absolutely zero radiation would have on an individual. And on a population (e.g. would evolution be harmed by having no radiation at all?)

I would say that ionizing radiation isn't the cause of most genetic mutations. It is just too rare and most of it doesn't penetrate the skin anyway, the rest has to be really lucky to hit the cell in the right place at the right time.

DNA copying not being perfect would be the main cause in my opinion.

There is one error on average for every billion pairs copied. The human DNA has 3 billion pairs. So every time a single(!) cell is copied, three mistakes are made.

You don't need any radiation for evolution.

But why are those mistakes made? Radiation?

It certainly could be, but I think most mistakes are made because of how the process is 'designed'; sometimes an incorrect molecule jiggles (literaly) into a place where it is improbable that it should.

What about other forms? Radiation is not radiation. There's gamma, X-ray, alpha, beta, neutron, microwave, infrared, etc. and they all have different biophysical effects.

Interesting link. Radiation hormesis seems to be a real thing.

https://en.wikipedia.org/wiki/Radiation_hormesis

Ah.. So, good guys TSA are just trying to improve public health with their scanners! And everybody is raging against them..

Risking cancer to diminish heart disease? lol no thanks. I'd rather eat vegetables and take a walk once in a while.

Don't walk in sunlight or you'll get exposed to low doses of radiation that "could" cause cancer. Also be cautious about where you buy those vegetables. There is a good chance they could contain things that also "could" cause cancer.

Relevant: http://kill-or-cure.herokuapp.com/

And then we get to the extreme paranoia where everything is generally recognized to cause cancer. And I'm not even convinced they're wrong, given the rates of cancer in people who (most likely) have never been exposed to anything (that they know of).

Although, then again, there's the problem of grandchildren of smokers getting cancer, when never having been exposed to the smoking first or second hand, only genetically through their parents.

Unless you are getting sunburns, this is not true. In fact, sunlight on skin promotes vitamin D production, which is known to help fight cancer.

The presence of a sunburn is orthogonal to the fact that you do, in fact, become exposed to radiation in sunlight. That is unequivocally true and trivially proven, whether you receive a sunburn or not.

I don't think the person you are replying to meant that sunlight exposure unconditionally causes cancer, and was simply addressing radiation scare and putting it in context.

All the downvotes notwithstanding, there is a direct correlation between the number of severe burns you've had and your chances of getting skin cancer[0], unless you have a genetic predisposition to skin cancer.

A moderate amount of sunlight on skin, without burning, is actually healthy for you, unless you 1) have various illnesses (lupus, for one), or 2) are genetically predisposed to skin cancer.

[0] http://www.webmd.com/melanoma-skin-cancer/news/20140530/5-or...

The say all we have to worry from the sun is skin cancer. That Solar flares don't cause other cancers. Remember this is the same science community and government that recommended margarine was safer than butter. That salt was dangerous and to be avoided which isn't believe to be be 100% accurate. They also created a food pyramid. We were told to eat lots of breads and pasta and fruit which contains sugars. People drank lots of juice. We were told to avoid foods with fat. Diabetes greatly increased ever since and now we are hearing it's the carbs and sugars that are more of a concern than fat.

We are told that mostly UV and electromagnetic radiation reach the earth and Sunlight is danger of skin cancer. Have we all read the peer reviewed studies and do we really know how often the sun potential sends a surge of Gamma radiation through your body? Isn't a great concern of long term solar system exploration about astronauts getting all sorts of cancer? How sure are we that the earth's atmosphere is protecting us from the same gamma radiation and that it isn't causing more than just skin cancer? Science evolves and surprises often occur. I personally am not so convinced that the Sun couldn't cause much more dangerous types of radiation myself but, I admit this isn't an area of research for me.

Banannas are radioactive. So are carrots and potatos, and some nuts and beans.

I mean, you'd have to eat a ton of bananas for that potassium to affect your body more than the potassium you already have in your body does.