I have been very interested in Jags since I first saw them in Hamburg in the late 1990s
As far as I can find there is absolutely zero mention of Neuro until approximately 2/3 years after the Germans Dutch ans Yanks introduced the IJ into the Jag line
With Jan Engels also firmly stating that his original Jags had no neuro and no contradictory statements made by any of his buyers my theory is that the IJs were a probable cause
I know not much about genetics
But each time I have mentioned this nobody has ever offered one scrap of proof that would make me even question my theory
In fact I have had several other people try to prove it wrong and end up coming to the same conclusion/assumption
I would be more than happy for anyone to prove it either right or wrong
Mainly because it might open a window that avoids any possibility of a similar thing happening in future
I think partly the reason the neuro went unnoticed... for as many years, is simply keepers that have a lot of animals (such as Jan Eric, leary, some of the first to have them and breed them out) don't often spend time "examining" them or handling them.
Outside of maintenance and feeding....no reason to mess with em. It's not like "like it" anyway.
So, with this fact...it wasn't til they started getting into the "newby keeper" hands (you know, the type of keeper that handles, takes out for walks, video tapes, etc) that it was noticed.
Remember, the first Jags....people spent huge money and, those type of keepers...don't necessarily risk their investments outside of their tanks.
Ad to the fact that some Morelia (such as jungles and chondros) act strange when not holding on to something. So, even if a slight neuro was noticed at first...was most likely blown off as a natural reaction to not being perched.
My thoughts anyway.
D