testing The soul has preoccupied humans for centuries. Our oldest ancestors believed the soul resided in the heart. Later, it was believed the soul was housed in other organs, including the liver and the spleen.

Eventually, when we could not find the soul in any of these locations, we decided that it must reside in the head, inside the brain. Yet the ancient Egyptians had little use for the brain: while they carefully mummified all of a deceased person’s organs, they drained the brain by inserting straws through the nasal passage into the cranial cavity and tossed the goo away.

Today, most scientists would argue that what we call consciousness is a by-product of the brain—that is, that the neural circuitry in the brain creates consciousness. Francis Crick, one of the discoverers of DNA, states in his book The Astonishing Hypothesis: The Scientific Search for the Soul that everything to be learned about the soul can be found by studying the workings of the human brain.

Shamanic healers are more prone to believe the reverse, that the brain is a by-product of consciousness That consciousness itself relies on complex and evolutionary mechanisms to create the neural circuitry that allows us to become aware of ourselves and the cosmos.