Spirituality, the keystone of all religions, is as old as the human race. Basically, spirituality is a belief in a supernatural being or thing. A supernatural being or thing is something that is outside the normal laws of nature- in other words, it is a soul, spirit, ghost or a god .
Primordial man probably made no clear distinction between animate and inanimate things. They believed that all beings and objects had spirits: other tribal members, animals they hunted (and which hunted them), rocks, trees, and the thunder and lightning. This concept, animism, is as old as humanity. When waking up after a vivid dream, it would have been natural for primitives to conclude that while their body slept, their soul, or spirit, wandered around having adventures.
Primordial man was instinctively a dualist. Dualists believe the mind is some sort of disembodied spirit that might leave the body and exist somewhere else (while a monist believes that mind cannot exist without matter, or the brain). To dualists, the idea of spirits or demonic possession would be natural.
This belief in spirits or the soul is the primary building block of religion, and likely dates back over 2 million years, to the time of Homo Habilis. Not the brightest spark by a long shot, but still bright enough to be considered truly human, they had the ability to fashion crude stone tools, which would require at least a bit of elementary logic.
While the earliest humans may have considered spirits were a fact of life, that is not the same thing as saying they venerated them, or even ascribed any special characteristics to them. A key question is when did spirituality give birth to religion?
To answer that, it is necessary to define what constitutes a religion. In 1983, the High Court of Australia held that "the beliefs, practices and observances of the Church of the New Faith (Scientology) were a religion in Victoria." As part of the ruling, it was stated that:
"For the purposes of the law, the criteria of religion are twofold: first, belief in a Supernatural Being, Thing or Principle;
and second, the acceptance of canons of conduct in order to give effect to that belief."
Whatever primordial man's relationship was with this multitude of spirits, by the mere act of believing in them, they had already met the first test of religious behaviour.
Certainly, primitive man feared many of these spirits, and at some point would come the idea to propitiate them with sacrifices and prayers. When this happened, the second test for religious behaviour would have been met- the acceptance of canons of conduct in order to give effect to that belief. This stage marks the boundary between spirituality and religion.
Just when early man reached this stage of religious development is probably impossible to say. We cannot know with any certainty what went on with human thought processes 50,000 years ago, let alone 2 million. It could be argued that if it depended upon the emergence of language, then 50,000 to 100,000 years ago might be considered a ballpark figure. There must have been a rather lengthy twilight time before these various aspects of religious behaviour started to merge.
From that point on, all religious history has been a process of mere tinkering. Plug in god (A), select sacrifices (B), offer prayer set (C), and embellish with rituals (D). The only modern contribution (a negative one) came about when priests decided to expand their mandate and tell believers how to live their lives.