Roundback or pointback?

actual cranebird

actual cranebird

As the folding of the TEDxNijmegen crane birds progresses it is interesting to notice that people are folding two varieties of birds. The ones with the rounded back (fig. 1) and the ones with the pointed back (fig. 2). This leads to the question how these two varieties evolved and how they co-exist nowadays.

The oldest source of documentation on the paper crane is possibly the standard work of origami Hiden Renzuru no Orikata from 1797 (see fig. 3). Here the circumdorsum variety is clearly visible. From this fact we can easily derive the hypothesis that the punctumdorsum variety was created by people who neglected to pull the two wings apart to create the rounded back. And as so often in nature, a small mistake can lead to the birth of a new variety of species.

So tell me, what sort of folder are you? Round of pointed? Circum or punctum? Let us know. With your comments you will provide us with usefull data to gain more insight in the spatial variation of the crane bird varieties.

Fig 1. Grus papyrus var. circumdorsum

Fig. 1 Roundback








Fig 2. Grus papyrus var. punctumdorsum

Fig 2. Pointback








Fig 3. Page from Hiden Renzuru no Orikata (1797)

Fig 3. Hiden_Senbazuru_Orikata











A blog by Marcel Wortel

TEDxNijmegen biologist