Once you have built the Great Ark, you can select a new island to sail to with your tribe. Here are a few pointers for preparing for the move.
First, once you arrive there, you will have all of the goods from your previous islands, but no buildings except for the kitchen. The first task, then, will be massive construction. Make sure that while you are building the ark in your old island, you have your woodsman and your rock gatherer (or multiple if you have them) refill the rock and woods storehouses, and make sure that your foodhouse is full so that you will have plenty of building supplies. If you work it right and have full storehouses before the relocation, you should have enough materials to easily build all of your new storehouses, your science building, several new huts, a new dock, and even several building upgrades before you need new materials.
Before you sail to the new island, click on the construction task in the status window of ALL of your tribesmen. Since your storehouses will be overstocked, they won't have anything else to do until you've built new buildings anyway. Chances are, you'll probably have more than 10000 science points, so your scientists will just be sitting around until you build and upgrade the science building unless you assign them to construction. By the way - in case you didn't know it - you can have more than one task active at a time. For example, if you have farming and construction clicked, the farmer will rotate between tending farms and helping build stuff. That said, it's probably good to have all of your tribesmen with some points in construction, and you may even want to have some extra sets of construction clothing prepared to give a boost to your building effort.
So... if you lose all of your buildings, lose your ark, and have to start basically from scratch every time you move, why on earth would you leave your first island? Change of scenery, solve more mysteries, or maybe because that's the ultimate climax of the game, and if you don't, you never really did anything anyway.