̽��ֱ�� of Cambridge - superhero

Why Spider-Man can’t exist: Geckos are ‘size limit’ for sticking to walls

jeh98 — Mon, 18 Jan 2016 20:05:00 +0000

A new study, published today in PNAS, shows that in climbing animals ranging in size from mites to geckos, the percentage of body surface covered by adhesive footpads increases as body size increases, setting a limit to the size of animal using this strategy because larger animals would require impossibly big feet.

Dr David Labonte and his colleagues in the ̽��ֱ�� of Cambridge’s Department of Zoology found that tiny mites use approximately 200 times less of their body surface area for adhesive pads than geckos, nature's largest adhesion-based climbers. And humans? We’d need as much as 40% of our total body surface, or roughly 80% of our front, to be covered in sticky footpads if we wanted to do a convincing Spider-Man impression.

Once an animal is so big that a substantial fraction of its body surface would need to be sticky footpads, the necessary morphological changes would make the evolution of this trait impractical, suggests Labonte.

“If a human, for example, wanted to climb up a wall the way a gecko does, we’d need impractically large sticky feet – and shoes in European size 145 or US size 114,”says Walter Federle, senior author also from Cambridge’s Department of Zoology.

“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 an elephant is mostly volume with not much surface area” explains Labonte.

“This poses a problem for larger climbing animals because, when they are bigger and heavier, they need more sticking power, but they have comparatively less body surface available for sticky footpads. This implies that there is a maximum size for animals climbing with sticky footpads – and that turns out to be about the size of a gecko.”

̽��ֱ��researchers compared the weight and footpad size of 225 climbing animal species including insects, frogs, spiders, lizards and even a mammal.

“We covered a range of more than seven orders of magnitude in body weight, which is roughly the same weight difference as between a cockroach and Big Ben” says Labonte.

“Although we were looking at vastly different animals – a spider and a gecko are about as different as a human is to an ant – their sticky feet are remarkably similar,” says Labonte.

“Adhesive pads of climbing animals are a prime example of convergent evolution – where multiple species have independently, through very different evolutionary histories, arrived at the same solution to a problem. When this happens, it’s a clear sign that it must be a very good solution.”

There is one other possible solution to the problem of how to stick when you’re a large animal, and that’s to make your sticky footpads even stickier.

“We noticed that within some groups of closely related species pad size was not increasing fast enough to match body size yet these animals could still stick to walls,” says Christofer Clemente, a co-author from the ̽��ֱ�� of the Sunshine Coast.

“We found that tree frogs have switched to this second option of making pads stickier rather than bigger. It’s remarkable that we see two different evolutionary solutions to the problem of getting big and sticking to walls,” says Clemente.

“Across all species the problem is solved by evolving relatively bigger pads, but this does not seem possible within closely related species, probably since the required morphological changes would be too large. Instead within these closely related groups, the pads get stickier in larger animals, but the underlying mechanisms are still unclear. This is a great example of evolutionary constraint and innovation.”

̽��ֱ��researchers say that these insights into the size limits of sticky footpads could have profound implications for developing large-scale bio-inspired adhesives, which are currently only effective on very small areas.

“Our study emphasises the importance of scaling for animal adhesion, and scaling is also essential for improving the performance of adhesives over much larger areas. 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,” says Labonte.

This study was supported by research grants from the UK Biotechnology and Biological Sciences Research Council (BB/I008667/1), the Human Frontier Science Programme (RGP0034/2012), the Denman Baynes Senior Research Fellowship, and a Discovery Early Career Research Fellowship (DE120101503).

Reference:

Labonte, D et al "Extreme positive allometry of animal adhesive pads and the size limits of adhesion-based climbing." PNAS 18 January 2016. DOI: 10.1073/pnas.1519459113

Inset images: Vallgatan 21D, Gothenburg, Sweden (photo by Gudbjörn Valgeirsson, footprints added by Cedric Bousquet, ̽��ֱ�� of Cambridge); How sticky footpad area changes with size (David Labonte); Diversity of sticky footpads (David Labonte).

Latest research reveals why geckos are the largest animals able to scale smooth vertical walls – even larger climbers would require unmanageably large sticky footpads. Scientists estimate that a human would need adhesive pads covering 40% of their body surface in order to walk up a wall like Spider-Man, and believe their insights have implications for the feasibility of large-scale, gecko-like adhesives.

If a human wanted to climb up a wall the way a gecko does, we’d need impractically large sticky feet – and shoes in European size 145

Walter Federle

A Hackmann & D Labonte

Gecko and ant

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Men of wonder: gender and American superhero comics

ns480 — Tue, 01 Nov 2011 13:00:35 +0000

Superman, the iconic ‘Man of Steel’ clad in red and blue spandex, made his first appearance in in the pages of Action Comics #1 in 1938. Batman debuted a year later in 1939. ̽��ֱ��stories of their exploits, and those of dozens of other heroes and villains appearing in the pages of the comics published by DC, have been told continuously for the past 70-odd years. Needless to say, that represents quite a lot of reading for anyone trying to get ‘caught up’, and it has become increasingly difficult over the years for these venerable superheroes to attract new comics-reading fans.

So, on 31 August 2011 DC Comics rebooted all of its continuing series, 52 separate titles in total. ̽��ֱ��‘reboot’ has become a relatively common practice among the two big American superhero comics publishers Marvel and DC, and it allows writers to reimagine—or discard altogether—a complex buildup of decades of story continuity. ̽��ֱ��‘New 52’ launch would, DC hoped, reverse slumping sales figures and attract the attention of a new generation of readers to their brands. Unfortunately, in the weeks that followed it became clear that the main effect of the reboot was attention of a much less desirable sort—that of attention generated by controversy.

̽��ֱ��controversy in question hinged upon the depictions of some of DC’s female characters. Catwoman, Batman’s sometimes-antagonist, is shown having sex with Batman on the roof of a building in the finale of Catwoman #1. Another superheroine named Starfire, appearing in Red Hood and the Outlaws #1, is drawn like a centerfold from the swimsuit issue of Sports Illustrated and has become a promiscuous amnesiac. While some readers defended these creative choices, others, particularly women, were appalled. Laura Hudson wrote the following for Comics Alliance: ‘When I read these comics and I see the way the female characters are presented, I don't see heroes I would want to be. I don't see people I would want to hang out with or look up to. I don't feel like the comics are talking to me; I feel like they're talking about me…’

It would, in fact, be pretty safe to say that most superhero comics are indeed talking ‘about’ women and not ‘to’ them. American superhero comics, and the sexual objectification of their heroines, reflect the conditions of their production and consumption: they are made almost exclusively by and for men. For 2011 blogger Tim Handley has been tracking the ratios of men versus women credited in the production of new Marvel and DC superhero comics released each week and finds that women account on average for less than ten percent of the labour and are concentrated in less prestigious roles. These industry trends are mirrored by the readership demographics; estimates suggest that ninety percent or more of mainstream superhero comics readers are male.

Why are superhero comics so masculine? After all, other comic book-loving countries such as Japan and France do not manifest the same trends, and the self-same superhero characters, when presented in another medium such as Hollywood film, have truly mass appeal. ̽��ֱ��answer to this question lies with two key events in the history of comics in the United States: 1) the institution of the Comics Code in the 1950s and 2) the rise of the direct market in the 1980s.

Concerns about the graphic depictions of sex and violence in comics built in the 1950s, culminating in the 1954 book by the psychiatrist Fredric Wertham Seduction of the Innocent, which linked juvenile delinquency to objects of popular culture, particularly comics. ̽��ֱ��same year, the U.S. Senate convened a subcommittee on juvenile delinquency, and the comics publishing industry, eager to head off any spectre of government regulation, formed its own self-regulatory body. This body, the Comics Magazine Association of America, adopted what came to be known as the Comics Code, a list of criteria meant to scrub comics of any and all questionable content. Excessive violence, nudity, and the glorification of criminality were all prohibited and soon had a chilling effect upon the industry’s creative output. ̽��ֱ��only the superhero genre of boyhood wish fulfillment fantasy was left standing.

Of course, the sanitised, eternal triumph of good over evil quickly gets boring, and by the 1970s newsstand sales of comic books were declining alarmingly. Publishers would print books only to have them returned unsold a few weeks later. This led to the rise of direct market distribution, where merchandise, unlike that sold to bookstores or newsstands, could not be returned. In other words, the risk of the sale of a comic book was transferred from the publisher to the distributor and the retailer. Retailers were given a larger discount on small orders of merchandise in return, and this encouraged the growth of small comic book shops catering to a specialised clientele of diehard—and male—fans.

Ironically, while in the short term the direct market undoubtedly saved superhero comics, in the long run it has been slowly killing them. Comics shops are, in the words of comics critic Douglas Wolk, ‘deeply unfriendly places’. He continues in this vein in Reading Comics, ‘Everything about them says, “You mean you don’t know?” In some of them, even new pamphlets and books are sealed in plastic before they go out on the shelves; if you don’t walk into the store knowing what you want, you’re not going to find out’. ̽��ֱ��more publishers depend upon the direct market for their sales, the more impenetrable and narrowly-focused upon their most loyal male readership their content becomes.

Although comics companies abandoned the Comics Code for good in the 1990s, the influence of the direct market upon the maleness of superhero comics has only strengthened over time. And the controversy surrounding DC’s ‘New 52’ reboot points to the industry’s ongoing failure to appeal persuasively to new—namely women and children—audiences. Indeed, my own research into the ‘manga boom’ of the 2000s demonstrates that the only way to sell comic books to women is to abandon the comics publishing mode of production and direct market distribution altogether and turn instead to trade book publishing. Therefore, the reboot is unlikely to reverse current trends, and superhero comics content will continue to be governed by the men who make and read them.

Yet there is absolutely no reason why any genre by and for men need trade in the wholesale sexual objectification of women. Therefore, I applaud grassroots efforts like the 30 October Women of Wonder Day, which brings together comics fans, retailers, creators, and other industry insiders to raise money for victims of domestic abuse. ‘Women of Wonder’ is an allusion to Wonder Woman, one of DC’s most popular female superheroes. This annual event, founded in 2006 by longtime Wonder Woman fan Andy Mangels, has raised over USD $110,000 to date and offers renewed hope that perhaps someday the superhero genre can be male-oriented without being misogynist.

Boys and action comics go together like Batman and Robin – but how are girls represented in comics? Sociologist, Casey Brienza, investigates the male world of the action comic and looks at the depictions of female characters.

Starfire, appearing in Red Hood and the Outlaws #1, is drawn like a centerfold from the swimsuit issue of Sports Illustrated and has become a promiscuous amnesiac.

Casey Brienza

̽��ֱ�� of Cambridge

Casey Brienza

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