Fear is contagious. Natural selection has wired us to sense fear in our surroundings and make it our own. Zebras might not get ulcers from chronic stress but those that fail to activate their acute stress response when others around them are stressed are more likely to miss cues of threat and be consumed by a predator. Absorbing secondhand stress from others is a survival instinct—an adaptation shaped by prehistoric environments to promote evolutionary fitness.
However, our culture is evolving faster than our ability to biologically evolve. Too often, we helplessly rubberneck trainwreck events—often sensationalized by media for attracting attention and profit—despite their remote connection to our personal survival. For example, fear of the Ebola virus in recent weeks has become more viral than the virus itself. In the modern technology age where fear memes can spread around the globe near-instantly, our tendency to absorb secondhand stress from our ubiquitous, 24/7 media culture to activate our own stress response can produce maladaptive responses that are out of proportion to the actual threat.
You are probably aware of the concept of second-hand smoke, which increases the risk of disease and death. You should probably be aware of another deadly scourge: second-hand stress.
Natural selection has wired us to sense the stress of others and make it our own. If you are a gazelle and you don’t freak out when others around you do, then you might be the one about to be consumed by a predator you haven’t seen yet. Animals detect the stress of others through various sensory signals such as alarm calls, olfactory cues, or visual behaviors. Plants detect distress signals of others in the form of ethylene gas that activates their own stress response (fittingly, second-hand smoke contains ethylene). The ability to detect second-hand stress is a survival instinct that can promote evolutionary fitness.