Scientist Claims Intelligent Aliens Are Likely 650 Pounds

Tuesday, 07 April 2015 - 3:25PM
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Alien Life
Tuesday, 07 April 2015 - 3:25PM
Scientist Claims Intelligent Aliens Are Likely 650 Pounds
Between E.T., Yoda, and any number of anthropomorphic movie aliens, we tend to envision extraterrestrial intelligence as the size of humans or even smaller. But according to cosmologist Fergus Simpson, intelligent beings on other planets would likely look less like the tiny Arquillians in Men in Black (above) and more like a tiger or polar bear, at least in regards to their size.

In his study, Simpson assumes that there is a minimum size for an organism to achieve intelligence. Larger animals require more resources than smaller animals, so their population density would presumably be inversely proportional to their size. Since inhabitable exoplanets are likely to be significantly smaller than Earth, we can assume that there would be a lower population density of these intelligent beings than the population density of humans on Earth, and therefore the organisms themselves would be much larger.

"Most inhabited planets are likely to be closer in size to Mars than the Earth," Simpson wrote in his paper. "[S]ince population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300kg."

Other scientists have agreed with Simpson to an extent, but have voiced several concerns about his methodology. "I think the average size calculation is reasonable," University of St. Andrews physicist Duncan Forgan told Newsweek, before qualifying that the paper "doesn't address the correlation between body mass and the planet's surface gravity."

A strong gravitational pull is associated with smaller organisms, while a weak gravitational pull may lead to larger organisms. Forgan believes that if Simpson had taken this factor into account, it "might push the mean size down a bit, but it's hard to say without doing a much harder calculation."

Furthermore, Simpson may have placed too much stock in the correlation between animal size and intelligence, rather than taking a variety of evolutionary factors into account. According to SETI's Seth Shostak, humans evolved to be intelligent mostly as a result of the advent of opposable thumbs and the ability to walk on two legs, rather than our size. 

"Polar bears are large but do not write great literature and build radio towers," said Shostak, "and a lot of that is probably because they are walking around on all fours."
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