In Southeast Asia (which is probably the home of the chicken) and in treeless villages, chickens will "roost" on the ground, under buildings.
When a hen is seen looking for a nest, a basket will be made and placed high enuf that dogs can't bother her. Usually, the rooster is picked up and placed in the nest basket first and shows the hen where it is. The hen will move into this nest about 5 feet above the ground and begin laying eggs there.
The chicken can vary its, shall we say, orientation in nesting and roosting depending on the environment. Easiest in a coop has to be roosts high and nests low.
Steve