There is hypothesis that archaic humans may have lived in trees until about 40000 years ago. Tree platforms or nests were used as a shelter from dangers on the ground. Even today, some indigenous people build tree houses in order to escape the danger and adversity on the ground in some parts of the tropics.
Nowadays modern tree houses may be integrated into existing hotel facilities. Along with subterranean and ground level houses, tree houses are an option for building eco-friendly houses in remote forest areas, because they do not require a clearing of a certain area of forest. There are numerous techniques to fasten the structure to the tree, which seek to minimize tree damage. Also the houses may be built with recycled materials. These tree houses can be used for recreation, workspace, habitation, and observation.
Most tree houses are usually built as play areas for children or for
leisure purposes. I remember when I was a child we used to climb in to trees
seeking for different viewpoint and possibility to enter my own world. There was
something special being in the tree and being connected with the nature that way.