[quote=XecutionerRex]
If you're talking about the man eating brothers of Tsavo I've never heard any suspicions concerning them being shapeshifters. Care to post a link?
[/quote]

Mostly its accounts from the workers there, recorded best by Lt. Colonel John H. Patterson who recounted that the railroad workers believed them to be shapeshifting demons or, in some cases, people who were hunting them because they were viewed as invaders but had the supernatural ability to assume leonine forms. You can also hear some discussion on this matter [url=http://podcasts.howstuffworks.com/hsw/podcasts/symhc/2013-12-16-symhc-lions-of-tsavo-1.mp3]here in a podcast from HowStuffWorks.com[/url] where the two hosts are reading passages from the Colonel's book, [i]The Man-eaters of Tsavo[/i]. You can find the specific recounting at time code 6:20 until 7:50 where the hosts conclude talking about another episode and its relation to zoanthropes (and shapeshifters) as a whole.

Some of this is my theory as well; many of the rail workers were poor men from India and some of their personal beliefs on incidents like this blended with some already established shapeshifting lore for the region as well as their own, but again that's my theory as to how or why some did see The Ghost and The Darkness as shapeshifters.