Popular culture has long been enchanted with the idea of little green men. But according to a recent paper, the average height of an intelligent extraterrestrial may be more than nine feet – and it would weigh in at a whopping 300kg (661 lbs.).
In his March 2015 abstract, The Nature of Inhabited Planets and their Inhabitants, researcher Fergus Simpson delivers a mathematical formula based on a variety of factors, including an assumption that extraterrestrials are subject to the same laws of conservation of energy as animals do on Earth.
Along with the theory that the larger a planet (among other factors), the more likely it is to be able to sustain life, this means aliens could have body masses as heavy as polar bears. Putting all that weight into human-like proportions means the average intelligent extraterrestrial could be taller than the largest people ever recorded on earth, including the famous 8’11” Robert Wadlow.
Simpson said in a Newsweek article about the paper that this would mean humans were “the ants among intelligent species.”