Indeed. A combination of dehydration and the LACK OF humidity can cause pyramiding.
Like Aldabraman said, it was trial and error from a number of dedicated tortoise keepers over the past decade or so. It wasn't as if someone woke up one night and thought "Nah, I don't think its diet and poor lighting. I 'think' its humidity." Well, maybe it did, but instead posting an empty claim/opinion, they went out and experimented to prove out the theory. Observations show that they were right.
There was an Austrian study that proved it in 2003. Richard Fife and his wife "discovered" it by accident in 2001, did some experiments with it and published it in Richard and his brother Jerry's "Leopard Tortoises" book in 2007. Many keepers of redfoots, like Carl May knew this in the 60's and 70's, but it has only recently been applied to species that are erroneously know as "desert" animals, like sulcatas and leopards.