The source of Superman's powers changes subtly over the course of his history. It is originally said that Superman's abilities derive from his Kryptonian heritage, making him eons more evolved than humans. Soon after, it is established that Krypton's gravity had been stronger than Earth's, a situation similar to that of Edgar Rice Burroughs' John Carter. As Superman becomes increasingly god-like, the implication that all Kryptonians had possessed the same abilities became problematic for writers, making it doubtful that a race of such beings could have been wiped out by something as trifling as an exploding planet. In part to counter this, the Superman writers established that Kryptonians, whose native star had been red, only possessed superpowers under the light of a yellow sun. More recent stories have attempted to find a balance between the two explanations.