Mice with human-like brains

Early death for Algernon:

Scientists create big-brained mice… Adding an extra version of a single gene makes mice grow big brains – brains so large they have to fold up, much as human brains do, to fit inside the skull, researchers said Thursday. It is not yet clear whether the mice are smarter – they were all killed soon after birth – but the scientists said they were surprised that one gene had such a strong effect and said they would do further experiments.

(My question is, why did they kill 'em?) Link Discuss (Thanks, Stefan!)