On the way to and from work each day, I keep being overtaken by these kids gliding past me. The first time I did a double take, but then I realised that they were wearing shoes with wheels in the bottoms of them - a kind of trainer-cum-rollerskate. Judging by the number I've seen, these shoes seem to be a huge fad - although collegues have pointed out to me that kids visiting the Science Museum (where I work) are probably more likely to be the type of kids who are into these shoe-skate things than is average. Nevertheless, I've seen enough kids wearing them to have been intrigued enough to research the fad.
The main company that produces these shoes seem to be called 'Heelys' - which is also the brand name they use for the shoes. 'Freedom is a wheel in your sole', their website proclaims, alongside videos of people doing 'tricks' with the shoes. The difference from rollerskates though (or rollerblades - which I've recently bought a pair of), is that the shoes are designed to be worn all the time, not just for a quick skate around the local park. Because they've only got a single wheel in each of the heels (hence the name), you can also walk or run in the shoes quite comfortably. The wheel isn't retractable into the sole (as I had originally imagined), but can be easily removed - although I've seen kids walking normally with the wheels still in.
The technique for skating seems to be completely different from normal rollerblading, where you propel yourself by pushing out and backwards with alternate feet, like iceskating. You skate instead by pushing yourself forward with the front of your foot and then switch into gliding with the two heels of your feet, your toes angled upward. It's odd to watch, but the kids seem to take to it fairly naturally (although Wikipedia's Heelys article notes that some doctors have concern about spinal damage).
One of the things that fascinates me about these 'Heelys' though, apart from the fad appeal, is that they seem to be an adaptation taken up by children which enables them to interact better with their environment (by moving faster, with less effort). What's more, this adaptation attempts to integrate the wheel into everyday personal movement. The inventor, Roger Adams, learnt to rollerskate aged nine months, but it wasn't until he was 49, and a psychologist going through a mid-life crisis, that he came up with the idea for the shoes, modding a Nike trainer by inserting a skateboard wheel into a hollowed-out heel.
It's not too difficult to see where the idea came from either. As a civilisation, we humans are fascinated by the wheel, learning from an early age the history of its development and subsequent consequences. Yet despite the ubiqity of the wheel in modern transportation, we see it very little, if at all, in nature. I always wondered why this was as a child, and I sure wasn't the only one.
The artist MS Escher came up with his idea of an animate using the wheel, in a lithogram called 'Curl Up', which depicted a made-up creature called the 'pedalternorotandomovens centroculatus articulosus' that could curl up into a ball and use its feet to push itself along. A neat idea, but as I spotted as a child, this is more like rolling - and not too dissimilar from what woodlice can do - and doesn't use the axel-based wheel motion that humans have manufactured.
Richard Dawkins has suggested why he thinks no animal has evolved the wheel, as outlined in an article 'So why don't animals have wheels?' - originally published in the Sunday Times, November 24, 1996:
A large creature would need large wheels, which, unlike man-made wheels, would have to grow in situ rather than being separately fashioned out of dead materials and then mounted. For a large, living organ, growth in situ demands blood or its equivalent. The problem of supplying a freely rotating organ with blood vessels, not to mention nerves, that don't tie themselves in knots is too vivid to need spelling out. Human engineers might suggest running concentric ducts to carry blood through the middle of the axle into the middle of the wheel. But what would the evolutionary intermediates have looked like? Evolutionary improvement is like climbing a mountain (Mount Improbable).
Even if you don't consider the axel-problem, the use of a wheel in nature is also questioned. After all, to make use of a wheel, you need flat, smooth surfaces.
Back to the original theme of the article - and I will be interested to see whether the shoe-rollerskate will make the leap into more mainstream use, perhaps even amonst adults. After all, it wasn't all that long ago that you could see suited-businessment scooting to work on those kids metal foldup scooters that were all the rage...