However, not all technical inventions are naturebased in the sense of ideas directly adopted from observed wildlife, and hence the human originality for these kinds of inventions is perceived to be of even higher value. One of the most important examples for a seemingly nature-independent cultural achievement is usually considered the invention of the wheel (e.g., Bronowski, 1976; Weiß, 2007). It is almost trivial to stress the importance of wheels and, more generally, the circular movement around an axis for our technical world and modern human culture. Wheels are virtually everywhere and if - in a thought experiment - every wheel and wheel-like function would suddenly disappear, all modern societies, even those only modestly technical, would collapse immediately. The universal high esteem for wheels is embedded in a long history of human fascination by round and circular objects and processes (see Bronowski, 1976; Jaffé, 1982; Wullen and Ebert, 2006). One only has to think of the admiration for the sun or the moon in many cultures, the circular appearance of seasons leading to round calendars, the circle and bowl as perfect geometrical shapes etc. Accordingly, the invention of the wheel is con-sidered as one of the most important cultural achievements.
There are numerous essays and accounts from different perspectives, all dealing with the question of why the evolution of plants or animals did not lead to wheel-like structures, or to what extent the basic principles of rotation are realised by organisms (e.g., Gould, 1981; Walker, 1991; Meyer and Halbeisen, 2006). Some of these treatments approach the problem by wondering why nature did not make use of such an obvious thing as a wheel and even artists show concern. In 1951 the Dutch artist M.C. Escher invented and displayed the imaginary animal Wentelteefje (“Curl-up”), Pedalternorotandomovens centroculatus articulosus, in two lithographs as a result of his ‘dissatisfaction concerning nature’s lack of any wheel-shaped living creatures endowed with the power of propulsion by means of rolling themselves up’ (Escher, 1967) (Fig. 2). These artiicial animals have a worm-like body shape and normally walk on six feet. Only under certain circumstances do they curl up and form a perfect round structure that is able to roll.