I suppose this doesn't fit on Wikipedia, but obviously one possible cause is that Cats are aliens from a planet abut 3.4 million lightyears away, and during that 7 million year period, all the cats left Earth suddenly because their planet needed them [1]. They used a near-light-speed vehicle to get there, solved the crisis on their home planet, then returned to continue their stewardship of Earth, and then the vehicle flew back.
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