Scientists Discover Why Spider-Man Can't Exist: Geckos Are 'Size Limit' For Sticking To Walls

Despite being bitten by a radioactive spider, researchers say Spider-Man would not be able to scale walls in real life.

A recent study from the University of Cambridge found the comic book superhero would need much larger hands and feet -- not to mention sticky-type pads covering up to 80 percent of the front of his body -- if he were to stick to and sling between city skyscrapers. Instead, researchers say geckos are the largest animals able to scale smooth vertical walls.

"If a human, for example, wanted to walk up a wall the way a gecko does, we'd need impractically large sticky feet -- our shoes would need to be a European size 145 or a U.S. size 114," Walter Federle, senior author from Cambridge's Department of Zoology, said in a news release.

For their study, researchers compared the weight and footpad size of 225 climbing animals, ranging from mites and spiders, to tree frogs, geckos and even a mammal. As animals increase in size, the proportion of body surface covered by adhesive footpads increases, thus limiting the size climbing animals can grow.

While tiny mites use approximately 200 times less of their total body area for adhesive pads than geckos -- nature's largest adhesion-based climbers -- a person would need 40 percent of their total body surface -- or 80 percent of their front -- to be covered in sticky footpads if they wanted to scale walls like these seasoned climbers.

"As animals increase in size, the amount of body surface area per volume decreases - an ant has a lot of surface area and very little volume, and a blue whale is mostly volume with not much surface area," lead scientist Dr. David Labonte explained.

This simply means that bigger and heavier species need more sticking power to cling to vertical surfaces, but have less body surface available to cover with adhesive pads.

"This implies there is a size limit to sticky footpads as an evolutionary solution to climbing - and that turns out to be about the size of a gecko," Labonte added, saying larger climbing creatures have evolved alternative climbing methods, such as digging in their claws and toes. (Scroll to read more...)

Their study, recently published in the journal Proceedings of the National Academy of Sciences, has implications for developing large-scale bio-inspired adhesives, which currently only work on small areas.

"Our study emphasizes the importance of scaling for animal adhesion, and scaling is also essential for improving the performance of adhesives over much larger areas," Labonte concluded in the university's release. "There is a lot of interesting work still to be done looking into the strategies that animals use to make their footpads stickier - these would likely have very useful applications in the development of large-scale, powerful yet controllable adhesives."

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