The Earth was highly radioactive four billion years ago when life emerged. Even today, all humans are bombarded by 20,000 radiation strikes each second. Although high doses hazardous, organisms have evolved not only to tolerate lower-dose but also benefit it (hormesis). Hormesis is prevailing in species various respects. An example that hibakusha (Japanese A-bomb survivors) longer lifespans and...

There is no place on the Earth, the planet we live on, where the natural background radiation level is zero. Since the birth and even in our fetal stage, we have been exposed to different sources of natural radiation. Life, in fact, evolved in a radiation environment that was much more harsh than today. Earth serves as a source of terrestrial radiation. Uranium, thorium, and radium are among th...