Aliens have always been a topic of excitement and mystery. Now, a cosmologist in Spain said that if they exist, they could be much bigger compared to humans and could weigh more than 300 kilograms. According to Fergus Simpson, a scientist at the University of Barcelona, the average weight of aliens could be beyond 300 kilograms.

This has been estimated by the expert on basis of a mathematical model, according to which, organisms on other planets comply with the laws of conservation of energy, which are observed on Earth.

It implies that larger animals require more resources and use more energy, and as a result they are less abundant. For example, small ants exist in large numbers, whereas whales or elephants are not that abundant.

According to Simpson, more small animals are present on earth than the larger ones. According to him, "Throughout the animal kingdom, species which are physically larger invariably possess a lower population density, possibly due to their enhanced energy demands. Since population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300kg".

Simpson added that since the number of planets occupied by comparatively small animals would be more in number than the amount of worlds where large ones predominate, it is expected that humans live on a planet with comparatively small animals and they are also probably one of the smaller intelligent beings.

According to 'Newsweek' report, Simpson said that a specific minimum size is probably essential for intelligent life. He also said that he made use of the range of body sizes found in animals on Earth to know about the most plausible distribution of organisms on other planets.