One of the stranger aspects of being human is the way that what is going on in one person’s mind affects what is going on in the minds of other people. On a physical level of course, we are all completely separate beings, each with our own body and our own personal space.
Yet when people get together, all sorts of strange transferences occur. It’s as though there is some sort of extra dimension, parallel to this one, in which bodies and brains are connected by a psychic cable.
My mood affects your mood, and your mood in turn affects the mood of the next people you meet. This mental transference can be either good or bad, but it is rarely negligible.
I guess it is a large part of what makes us human.
Not exclusive to humans. I only need one example: your pet dog.