"That modern humans got to Australia before they penetrated Europe suggests that Neanderthals held them off for millennia. That suggests they weren't that backward."
Instead, moderns were very, very lucky—so lucky that Finlayson calls what happened "survival of the weakest." About 30,000 years ago, the vast forests of Eurasia began to retreat, leaving treeless steppes and tundra and forcing forest animals to disperse over vast distances. Because they evolved in the warm climate of Africa before spreading into Europe, modern humans had a body like marathon runners, adapted to track prey over such distances. But Neanderthals were built like wrestlers. That was great for ambush hunting, which they practiced in the once ubiquitous forests, but a handicap on the steppes, where endurance mattered more. This is the luck part: the open, African type of terrain in which modern humans evolved their less-muscled, more-slender body type "subsequently expanded so greatly" in Europe, writes Finlayson. And that was "pure chance."
Two points: First neanderthals probably had the same intellectual capacity we have today; Second, modern humans evolved to run.