Mice forced to breathe hydrogen sulfide — known best for its rotten egg smell — go into a kind of suspended animation, U.S. researchers said on Thursday in a finding that may help save human lives. Although hydrogen sulfide gas is toxic in high doses, it may activate some of the mechanisms that cause other animals to go into hibernation, they wrote in this week’s issue of the journal Science. “We are, in essence, temporarily converting mice from warm-blooded to cold-blooded creatures, which is exactly the same thing that happens naturally when mammals hibernate,” said Mark Roth, who led the study, in a statement. “We think this may be a latent ability that all mammals have — potentially even humans — and we’re just harnessing it and turning it on and off, inducing a state of hibernation on demand,” said Roth, a biochemist.