Could an attacking 50-foot woman actually exist?

September 14, 2012

Dear Cecil:

The science fiction movie Attack of the 50 Foot Woman — that could never happen, right? Her bones would cave in under the weight of all that meat.

Cecil replies:

You might have expressed that more elegantly, Monk. However, you’ve put your finger on the problem. Though Attack of the 50 Foot Woman has attained a certain camp cachet, some still consider it the worst science fiction flick ever made. Even in 1958 audiences walked out of theaters muttering, "This movie lacks a plausible scientific basis." Had the filmmakers had a better grasp of physics and instead made Attack of the Woman of Somewhat Above-Average Height, their picture would surely rank among the classics of the cinema now.

Who’s to blame? The film schools, of course. They spend way too much time on Hitchcock, Kurosawa, and Coppola while Galileo gets short shrift.

Yes, Galileo. The Renaissance astronomer is justly renowned as a fearless champion of heliocentrism, but his rightful place in the filmic arts continues to be denied him.

Toward the end of his life, Galileo wrote Dialogues Concerning Two New Sciences, in which he laid the groundwork for what we now call kinematics, which is only one letter off from cinematics and has the same Greek root, kinema, motion. You think I’m joking? Not entirely. In his book Galileo explains why women, men, and critters in general can only get so big.

It’s called the Principle of Similitude. It says doubling the size of an animal while keeping its proportions the same increases the cross-sectional area of its muscles and bones by a factor of four while increasing its weight by a factor of eight. Simply put, strength increases with the square of height while bulk increases with the cube. This principle explains (among many other things) why people can’t fly like birds — our weight is too great in relation to our strength.

Likewise, if a woman starts off at five feet and 100 pounds and then grows to 50 feet, she’ll have 100 times the bone and muscle area but weigh 1,000 times as much — 50 tons. Far from being an avenging angel ready to smite her cheating husband, our heroine would barely be able to stand, and might snap a femur if she tried.

Even more likely, she’d pass out. A five-foot woman in good health has blood pressure somewhere around 110 over 60, which means each time her heart beats, it creates a pulse pressure of 50 mm of mercury (110 minus 60). If we assume the relative resistance of our 50-foot woman’s cardiovascular system stays constant, then for her heart to be able to pump blood to her brain and extremities, her pulse pressure would need to be 469 mm of mercury, or nine pounds per square inch. A heart of normal human proportions could never manage it. The entire cardiovascular system would need to be many times as large.

So would everything else. There are basically two ways in which a 50-foot woman might cope with the stresses of size. The first is to live in the water, whose buoyancy would support her weight — one reason the largest extant animals are whales. If full-time residency in the deep is too restrictive, she might go the hippopotamus route and spend most of her day in the nearest river, lake, or swamp.

Not the world’s worst lifestyle, but perhaps not one that lends itself to an action-packed film treatment. Let’s assume our 50-foot woman had to spend most of her screen time on dry land. Given the physical realities, how would she be built?

A brick shithouse doesn’t begin to capture it. In order to keep up with a doubling in body size, you’d need to increase bone and muscle thickness by 2.8 times, which is to say, the square root of 8. This works up to a point, as in the case of thick-legged and heavily-muscled creatures such as elephants and rhinoceroses. Our 50-foot woman, however, would need thighs 32 times as thick, making her a veritable grain elevator of flesh.

One may object that some animals cope with large size by evolving to become relatively thin and light for their height, such as giraffes. True, but think what that approach would mean if scaled up to 50 feet. You’d need limbs the thickness of soda straws supporting a piano-sized chest for the massive heart.

Let’s not forget heat buildup. Since body mass increases with the cube but surface area — and thus cooling capacity — with the square, it’d be tough shedding excess heat. A 50-foot woman would want minimal clothing, which on the plus side provides a scientific justification for the skimpy bathing suit depicted in the iconic 1958 movie poster.

But sustained exertion would result in overheating. Though the heroine might briefly rouse herself to swat a rival, she’d want to spend the rest of the film recuperating in the above-mentioned swamp. The ennui! Think what a Godard might have done with it. Instead, mere cheesecake. It’s sad.

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References

Alexander, R. McNeil “Palaeontological Association Annual Address. All-time Giants: The Largest Animals and Their Problems” Palaeontology 41.6 (1998): 1231-1245.

Bonner, J.T. “Perspective: The Size-Complexity Rule” Evolution 58.9 (2004): 1883-1890.

Flannery, Maura. “Small, Medium, or Large: Why Is Size So Important?” The American Biology Teacher 51.2 (Feb., 1989): 122-125.

Sander, P. Martin et al. “Biology of the sauropod dinosaurs: the evolution of gigantism.” Biological Reviews 86 (2011): 117-155.

Stanley, Steven M. “An Explanation for Cope’s Rule” Evolution 27.1 (1973): 1-26.

The Straight Dope: Why were dinosaurs big? http://www.straightdope.com/columns/read/888/why-were-dinosaurs-big

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