The tradional idea is that the soul enters with the eithers. Bodies can function without the soul. There is a difference between human individualized soul (psyche) and the animal group soul. Domesticated animals are humanized.

Reincarntion is a form of spiritual evolution. Your soul is a house for your spiritual body. You are more than a physical being, you are physical, emotional, mental, and spiritual, a human creation. You are not a robot computer, or are you? You are not a mechanical organism, though you may disagree. The universe is not mechanical. It is a living organisnm. It lives because of Spirit, The Great Spirit_ is the source of all existense be it material or non.

We breath in spirit. Without it we can not exist.

In the center of every cell there is a vacuum which is electromagntic. That is where the soul is. Prior to the point where you take your first breath, you are a part of your mother's body. Your soul exists and is waiting to take it's place in time. When your mission is complete you will be called back.