Aliens will be as large as the bear, says a new ‘scientific’ estimate

Going by the imagination of sci-fi writers and filmmakers, most life forms on other planets — tellingly christened ‘aliens’ — are always rather menacing to look at and villainous in intent. They are also usually larger than the average humans and are often represented as gigantic, snap-jawed insects complete with hairy probosces and legs. Not much serious thought is given to the probability of extraterrestrials looking the way we humans and our storylines want them to. But now that a scientist in Barcelona has plotted the relation between size and population — smaller species are more numerous than larger ones — on a curve against probability and reckoned that an alien’s median weight would be around 314 kg or no bigger than a bear or elk, the chances of giant, aggressive arthropods invading the Earth suddenly appear even more remote.

Luckily, the way to wriggle out of that constraint lies in the very Bayes theorem the scientist used to get his bear-sized thesis, as it posits how a subjective degree of belief should rationally change to account for new evidence. So, sci-fi enthusiasts can always hope that something will happen to activate the Bayes theorem again, reviving chances of giant pterygotal manifestations lurking somewhere in the vast recesses of space, waiting to pounce on our precious blue orb.