Mammalian behaviors are pretty well known; some trigger fight-or-flight responses and some do not. All mammals can read these signs from a long way off.

A loose, moderate pace, feet hitting the ground softly, head moving slowly about, looking with no particular focus, shoulders relaxed and down, and, if talking, a quiet, unhurried, soft-toned voice, signal "I am not fleeing or hunting, or a threat to you."

A tighter, quicker pace, feet hitting the ground hard, head on a constant quicker swivel, looking with laser-like intense focus, shoulders tensed and up, and, if talking, an intense. clipped, harsh-toned voice, signal "I am fleeing or hunting, and may be a threat if you catch my attention."

Of course, being the devious beings we are, knowing these things we can fake one or the other!

The science of body language is about these "vibes."