I have not read the full research paper but I expect that the researchers have been as thorough as they can in demonstrating that IBD was not previously common in these people's families or indeed their wider communities.
Having said that, here's a forum post from a chap in Ethiopia with CD so it does exist there
www.crohnsforum.com/showthread.php?t=10054I do agree that is is hard to compare with the past, I think that pre modern medicine I would have died from my pan colitis and may have gone down in the records as a young girl dead from some sort of dysentery. It would be fascinating to be able to find medical evidence from the East European Shtetls to see if people were suffering from IBD type symptoms long before the Ashke****s moved West.