This research discusses the idea that people shed stuff–wow, a stunning development. Not.
Watch your dog. So let’s say one of my dogs knows I have gone out and decides to find out where I am, he or she smells what I have dropped as I walk along–no big surprise–skin and other detritus drops off of us all the time, otherwise bloodhounds would be worthless to find little kids or victims of crime or bad guys on the lam.
And guess what, that means we leave a personalized trail that a dog can differentiate from other people’s trail.