having discussed this with my geneticist friend who worked on the genome , no gene disappears - it goes deep into storage . That is why the brindle is so interesting to me , if it emerges does this then mean other attributes are linked. Brindle was a colour pattern in the herding dogs of the northern regions, Holland , and they were or could easily have been included in the practical/functioning true herding dogs of the region which were returned to or incorporated a decade or so before the turn of the century. Just remember that the map of Europe has been re-drawn many times "The Dutch Shepherd was discovered as a naturally occurring shepherd's dog type living in the rural areas of the larger region that today includes The Netherlands"
Naturally occurring --- indigenous , just as the regions of Germany had indigenous types -
The breed standard was established at the same time period as the GSD "When the first breed standard
was written in 1898, the coat could be any color."
And this "But in 1914 it was decided to allow only brindle to distinguish the breed from the then similar German Shepherd
and Belgian Shepherd
The breeds eventually diverged into the three distinct breeds as known today" Curious that is was in 1914 - I guess an obvious distinction, pulling away from- disassociation - frictions between the blood-related monarchies and tinder box politics were apparent in 1914 .
The dogs even had the same herding style "Originally the main function of the Dutch Shepherd Dog was that of a shepherd’s dog in the countryside. From early times, the Dutch had an arable culture that was maintained by flocks of sheep. The dogs had to keep the flock away from the crops, which they did by patrolling the borders of the road and the fields. They also accompanied the flocks on their way to the common meadows, markets and ports"
Not the herding style of the collies - not the herding that is tested in herding instinct tests which is so far removed from the GSD style.
The brindle does point to the ancestry of the molosser
mastiff type as seen on this graph 13 of the Year's Best Infographics | Wired Design | Wired.com