The Trick of Magnifying Normal Creatures

The trick of magnifying a normal creature to menacing size is all too common. The giant amoeba is a familar example; monster insects (or whole populations of them) even more so. It might pay an author with this particular urge to ask himself why we don't actually have such creatures around. There is likely to be a good reason, and if he doesn't know it perhaps he should do some research.

In the case of both amoeba and insect, the so-called "square-cube" law is the trouble. Things like strength of muscle and rate of chemical and heat exchange with the environment depend on surface or cross-section area, and change with the square of linear size; Swift's Brobdingnagians would therefore have a hundred times the strength and oxygen intake rate of poor Gulliver. Unfortunately the mass of tissue to be supported and fed goes up with the cube of linear dimension, so the giants would have had a thousand times Gulliver's weight. It seems unlikely that they could have stood, much less walked (can you support ten times your present weight?). This is why a whale, though an air breather, suffocates if he runs ashore; he lacks the muscular strength to expand his chest cavity against its own weight. An ant magnified to six-foot length would be in even worse trouble, since she doesn't have a mammal's supercharger system in the first place, but merely a set of air pipes running through her system. Even if the mad scientist provided his giant ants with oxygen masks, I wouldn't be afraid of them.

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A rather similar factor operates against the idea of having a manlike creature get all his energy from sunlight, plant style. This was covered years ago by V. A. Eulach ("Those Impossible Autotrophic Men," Astounding Science Fiction, October 1956), who pointed out that a man who tries to live like a tree is going to wind up looking much like one. He will have to increase his sunlight-intercepting area without greatly increasing his mass (in other words, grow leaves), cut down his energy demands to what leaves can supply from sunlight's one-and-a-half-horse-power-per-square-yard (become sessile), and provide himself with mineral nutrients directly from the soil, since he can't catch food any more (grow roots!).