Short story where astronauts find a star to be the source of "evolution"

Question

A group of astronauts is set to explore a distant and interesting star. They do a few experiments, one of which is to expose some guinea pigs (or other kind of rodents) to the star's light.

The crew start losing teeth and hair and fingernails, and after a while they start developing telekinesis and mind-reading abilities. The star is eventually found to be the source of "evolution", and the more you are exposed to the star, the further you advance in evolution.

Near the end, one of the group wants to kill the others, only to be stopped by three light blobs, that are then revealed to be the guinea pigs, that in the mean time evolved to the very end of their evolving-line, and are now immaterial and god-like powerful.

The short story is from an old collection, almost surely written before 1970, possibly from some Hugo awards collection, or similar.

Answer 1

Philip K. Dick, The Infinites.

The plot centers around a crew of three on board a spaceship which scouts asteroid fields for new materials which can be mined. Led by Crispin Eller, the crew (which consists of second in command Blake and Silvia) land on an asteroid and send a pack of hamsters in order to check the radiation levels. Upon retrieving the hamsters, they discover that they've received a large doses of radiation and are lifeless.

Later, the crew themselves pass out of radiation and wake up several days later. Their hair falls out, their nails as well, and their heads swell to a larger size. Pondering over the changes, the crew realizes that the radiation has vastly increased their evolution, and that they've evolved millions of years in a matter of days. Blake insists on going back to Earth so they can assume control with their powerful minds, while Eller is more cautions. A fight breaks out, and Blake kills Silvia with energy he creates himself. As Blake is about to kill Eller, several large orbs of energy appear and destroy Blake. It is revealed that the orbs of energy are actually the hamsters which have received the radiation first, and have evolved millions of years and are now nothing but pure energy.

Answer 2

You can read the story here: The Infinites