That's the key, right there.  The Theory of Evolution (ToE) is a Great Wonder.  Wonders can only be built by one city, one civ.  As someone else has already beaten you to it, you are no longer to continue the production of it, and you have to change it to something else.  Sucks, don't it?  If there's another wonder you can build (unlikely at this stage of the game), then you should switch to that, as it would waste fewer of you shields than just building a unit or building, which would waste almost all of the built up production.

Welcome to the boards, btw!

You have several Civ's at the same stage of techs and all building the same wonders.

This happens mainly twice, (Sun Tzu's/Leo's/Sistine) and later in the Middle Ages with Bachs/Copernicus/Magellans/Smith's/Shakespeare's etc.)

I'm  not even going to mention the beginning of the ancient era, as there are to many wonders to mention and at that stage of the game, unless you're seafaring and have sent out curraghs everywhere, the only warning you get is "Civ X has just built the Great Library."

Wonder Cascade is something that's hard to avoid, but its possible.

1. Don't give techs to other civs that are building WoW's and can switch to it.

2.  While it's much harder, it's possiblt to time it so that two (or three) Wow's can be built on the same turn!  You have to know (or hope) that by managing you won't lose out on them.

But as PS said, good luck and welcome to the boards!'

I'm trying to remember...you CAN rush a wonder with a general...unit that you get from having an elite unit win a victory against an enemy civ (not barbarians)...at least I'm pretty sure...other than that, the only way is to beat the AI to the build.

And the AI checks EVERY turn to see if it can edge you out in shields.  You need to basically have it so that a city where you're building a Great Wonder produces so much that the AI has NO chance to beat you.

Another strategy is, as you're getting close (because they LOVE beating you by 1-3 turns), say 10 turns out from building the Wonder, is to give ALL AI civs a government changing technology.  They will immediately do so, and all but religious civs will have 4-8 turns of anarchy where they will not continue building the Wonder.

That depends on the version you're playing.  In conquests, it's the Scientific gl who can rush wonders. MGLs can still rush small wonders, but no longer do they have the ability to rush great ones.

Welcome!