Ich habe mal auf Arte eine sehr schöne Doku gesehen, in der Astrobiologen Planeten konstruierten (also, Modelle, nicht echte) und dann aufgrund der Atmosphäre, der Masse und der Gravitationswirkung Lebensformen auf diesen Planeten ableiteten. Aliens auf Planeten mit größerer Masse und deshalb größerer Schwerkraft wären also nicht so hochgewachsen und eher breit. Lebende Schleimpfützen, oder sowas. Der Blob. Wie auch immer.
Dieser Artikel von 1951 bei Modern Mechanix macht genau dasselbe, nur mit den Planeten unseres Sonnensystems:
Now let’s leap to Mars and observe a Martian as described by Major James R. Randolph, engineer, mathematician and physicist, who taught at Pratt Institute in Brooklyn, N. Y., and Rhode Island State College and lectures extensively on interplanetary subjects. This is his conception of a Mars inhabitant: He has slender arms and legs, a large chest, wide, flaring nostrils and a broad mouth. His head would be about a quarter the size of his body; his eyes would be dark-adapted, with wide pupils. His size is problematical— Major Randolph’s guess is that he would be about four feet tall but he frankly admits there is no real basis for the assumption.
Now, why would a Martian look like this? Gravity on Mars is only 38 per cent of what it is on earth, hence everything would be easier to push, pull, pick up and carry. If everything weighs less, there would be less need for muscle, hence the reed-like limbs.
Why the large chest, the wide mouth and nostrils? There is considerable evidence that Mars has an atmosphere but it is extremely thin and the pressure is very low. Now, says Major Randolph, since air occupies more space if there is less pressure, a Martian would have to take much more air into his lungs than we do and oversize organs would result.
The mouth and nostrils would be wide for the same reason—larger air spaces would be required. The head, encompassing a normal brain, would be the size of an earthman’s thus disproportionate to the rest of his body.