The sense of smell in the early human beings was a sense much more utilized than today. One of its uses was to recognize others (each person has a unique smell) and perhaps to understand mood, illness or other factors. This can be likened to when dogs smell each other to understand more about each other upon meeting.
It is fascinating to look at how some gestures that we still use today in society probably have roots in our prehistory and had their own practical utility linked to our olfactory abilities, and not just a ceremonial function. For example, it is believed that kissing was used to smell the person being kissed, and in some languages the term "kissing" still means "to smell" today.
Some scholars are trying to understand why we shake hands when we meet and one of the reasons may be linked to smell again. In fact, it has been shown that each of us has odorous molecules on our hands that are transmitted to the other hand during the squeeze. It has also been observed that after shaking hands, we tend to touch our faces (have you ever noticed?). The reason could be precisely this: "smell" the scent left by the other's hand during our handshake. Incredible right ?!
If you're interested in reading more on this topic click here to read the Newscientist.com article.
In times of COVID19 these practices are scary (or dangerous?!) at the very thought, but when we return to normal, hopefully we'll return to smelling.