Death is an experience every human eventually faces, yet it remains deeply mysterious. Its unknowns often stir fear, largely because people are unsettled by what they can’t fully understand. Still, bit by bit, science is uncovering clues that bring us closer to grasping what happens around the moment life ends.

For generations, people have spoken about a “sixth sense,” an instinct that alerts us to danger before we can explain it. Surprisingly, scientific research has begun to support the idea that humans may indeed detect certain signals without consciously realizing it.

One of those signals appears right after death occurs. As the body begins to break down, it releases a chemical called putrescine — a toxic compound with a harsh, decaying odor. Most people wouldn’t consciously recognize it, but the brain reacts instantly. Even at a subconscious level, the scent sends a powerful message that something is wrong.

Researchers Arnaud Wisman and Ilan Shira discovered that humans respond to putrescine much like animals do. In nature, the scent of decay signals danger, prompting creatures to flee, stay alert, or protect themselves. In experiments, participants didn’t realize they were smelling putrescine, yet they instinctively backed away or became more cautious.

“We aren’t always aware of why we like or dislike a smell,” the researchers said, noting how deeply scent influences emotions and behavior. Even without conscious awareness, people consistently demonstrated avoidance reactions.

Some scientists argue that fear triggered by scent is entirely possible. Just as pheromones can influence attraction, the smell of putrescine triggers the opposite response: tension, vigilance, and a desire to escape. The body senses the threat before the mind has time to understand it.

This suggests that long before we see danger, our nose may already be warning us. It’s a striking reminder of the hidden power of human instinct — and how much our subconscious detects long before we become aware of it.