On that note I set out to do some research. Here is what I found :
Our old factory response is :directly linked to the emotional center of our brain, causing a flood of warm and fuzzy feelings with a simple sniff. Unlike touch or taste, scents are directly correlated with past experiences.
While all the senses are connected with memories, smell in particular sparks a flurry of emotional memories. Why?After a smell enters the nose, it travels through the cranial nerve through the olfactory bulb, which helps the brain process smells. The olfactory bulb is part of the limbic system, the emotional center of the brain. As a member of the limbic system, the olfactory bulb can easily access the amygdala, which plays a role in emotional memories (it’s also where the "fight or flight" reflex comes from).
“Olfactory has a strong input into the amygdala, which process emotions. The kind of memories that it evokes are good and they are more powerful,” explains Eichenbaum.
“Smells do bring back memories,” says Dr. Ken Heilman, James E. Rooks Jr. Distinguished Professor Neurology and Health Psychology at the University of Florida and a member of AAN. “Smell goes into the emotional parts of the brain and the memory parts, whereas words go into thinking parts of the brain.”
This could explain why memories sparked by smell feel nostalgic and emotional, rather than concrete and detailed. Also, Eichenbaum notes that primates evolved to rely mostly on vision, not smell, so these memories are less reliable. (If you were a rat in his lab, your smell memories would be more detailed).