A few weeks back, I considered the question whether Magic The Gathering keywords are distributed in such a way that they reflect the specific structure of the color wheel. That is whether the allied colours share more keywords than enemy colours. Contrary to expectation, this was not the case. Rather the distance between allied and enemy colours was roughly equal.
Now we are going to attempt the same question but now looking at creature types. The results are more encouraging here. The underlying method is such that colours that share a lot of keywords are placed closely together and keywords that are shared by the same colours are placed similarly close. We produce a two-dimensional plot here. The colours are in the correct order: starting in the lower-left corner and moving up, we follow the order ‘White-Blue-Black-Red-Green’. The second thing that is notable is that a number of creature types are so concentrated that they can no longer be read. Essentially every colour has its own concentration. Black in the top middle position has a concentration (where we can read vampire). Blue has the same (around fish). White (below Angel) and Green (one can make out Druid) has the same. For Red the concentration is between dwarf and shaman. These are creature types that are in essence mono-coloured.
But other creature types are distributed more evenly between colours. As we can see in the figure, many of these are distributed between allied colours: monks, cats, scouts and horses between white and green; birds between blue and white; ninjas and rogues between blue and black, orcs and ogres between red and black, and finally beasts between red and green. A number of creature types are evenly distributed between all colours, Zubara, for instance. You can see the capitol Z in the centre.
Apparently, creature types are in contrast to key words distributed in a pattern that follows the colour wheel. The question arises, why the colour wheel is reflected in the one but not the other?
The first reason, is that flavor is an important part of the colour wheel. More than crunch, the alliances and enmities of the colours are fluff. Second and more practically, in order to balance the color pairs, creature keywords cannot be exclusively distributed among allied colour pairs. Flying cannot completely be concentrated in the colours around blue. That would weaken red and green too much. Third, playable strategies are developed for all colour pairs: whether enemy or allied pairs. Having a keyword is one way to do this. Ravnica is an extreme implementation of this, where every colour pair has a key word. Creatures by contrast, have less balancing concerns and are often strongly concentrated in particular colours and their allies.