The forming of a crest in stead of a comb is, certainly seen phenotypically, a radical change in the fowl. It changes the form of the skull by means of a bump formed raising, to offer space as for real to all the feathers that will grow on that spot. This change is perceived best in the little chickens.

It is not the case that by crossing fowl with a single comb and a crested chicken a complete tuft has been created immediately in the next generation. A large scale of in between forms, one better successful than the other, is shown, provided a large number of descendants.  To understand this better the presentation as by the Houdan is best, a fowl described for the first time in the seventeenth century, so in the same period of time in which Jan Steen painted "The Poultry Yard".  This Northern-French (Norman) breed got stuck, so to say, somewhere in the middle of the development from a fowl with a single comb to a full crested one. Seen this way it is also understandable that Darwin, apparently only judging the crest forms, has considered this breed with a fifth toe, together with the Crève Coeur, also a bearded Norman breed, but with a much better developed crest, and together with the wattled Polish, or as is said in the Netherlands: the Dutch Crested Fowl, to be subspecies of one and the same variety. For that matter, we should not forget in this all that as well the Houdan as the Crève Coeur originally not were meant as decorative fowl but as animals for use with priorities as laying eggs and providing tasteful meat.