One of the best pieces of evidence we have for early spirituality is in the caves at Lascaux, France. Deep inside magnificent paintings have been discovered of boars, bisons, bulls, bears and horses.
The paintings have been dated to the palaeolithic era (between 28,000 BC and 10,000 BC).
It is believed that in this era, people believed the rocks had spiritual life in them. The painting technique used, as can be seen in this video (http://whc.unesco.org/en/list/85/video) involves blowing the pigment onto the rock and so breathing life into the drawings on there. The thought then was that the animals drawn in the pigment would gain some of that power and energy from the rock.
The paintings indicate just one way in which our innate spirituality is linked to the natural world. We have an urge deep within us to work with nature and the energy it brings.
The early religions were sensually spiritual , instinctive and intuitive combined with a sense of awe at the natural world. Each type of plant, animal, tree, landscape feature was considered a Being in its own right with qualities and energy that needed respecting.
Local sites such as the caves at Lascaux became centres of religion and worship was a very localised event.
What is interesting is that despite this being local, the same features of early worship can be seen world over. All inspired by Nature and the Earth.