Sci-fi films and TV shows have routinely depicted a brutal race of aliens visiting Earth in their spaceships and enslaving unfortunate Earthlings. But according to one expert, extraterrestrial life may actually be too scared of'dangerous' and'violent' humans to want to come here. Dr Gordon Gallup, a biopsychologist at the University of Albany, argues that humans are'dangerous, violent and ceaselessly engage in endless bloody conflicts and war'. For this reason, aliens with the technological capability of making a visit to Earth - if they exist - are likely inclined to stay away for fear of death and genocide, according to Dr Gallup. No life beyond Earth has ever been found and there is no evidence that alien life has ever visited our planet.