nature.com: Humans may not have as many smell receptor genes as dogs, but we do have much bigger brains — and we can use them to become almost as good at tracking scents as dogs can. All it takes is practice.
… although we have fewer odour receptors than other animals, we may compensate for this with an improved ability to analyse scent information with our large brains. We may just seem worse at tracking scents because we don’t practice this skill from birth, the way that dogs do … in a few training sets, humans can achieve something that other animals spend their life being trained to do.
But while our analytic ability may be superior, we still don’t have the same ability to pick up and identify specific scents, like those of a particular person, traces of drugs, or explosives. With the possible exception of the protagonist in Patrick Suskind’s Parfum.