Too many haunted shows on TV right now. I have a theory that involves forensics, the biology of decay, microbiology, and pherimones It's validating, but also myth-busting.

It goes like this: someone is murdered in a house. Microscopic traces of blood spatter have been found to still be visible under luminol, long after its really "cleaned up" even 20 years later. A dog could probably smell that. We assume we humans can't, but, subconsciously, at pherimone level, there may be compounds that linger and cause unease.

Someone died and was buried in the earth. Long after the remains are gone, the make-up of the bacteria in the soil has been altered, a secondary trace of decay bacteria may linger. The soil ecology may be biased towards them, or related species. We assume we can't smell that or react to it. But what if we can?

What if even 1000 years later, we can, even if we're not consciously aware of it, just "feel" someone died here? Chemical distress signals etched into the environment in blood, bacteria, and decay?

Ghosts.