Over this long span, the only wavelengths that stimulate living things are
However, x-rays and gamma rays can be absorbed by DNA and damage it - causing mutations.
|Link to a discussion of other sources of ionizing radiation.|
Light makes possible a number of essential functions in living things:
Approximately one-half of the energy reaching the earth from the sun is light; that is, it is within the visible portion of the spectrum. The remainder arrives as heat and a small amount of ultraviolet light (which can, however, have a large effect on the aging of skin and the development of skin cancer).
|Link to a discussion of radiation and cancer.|