Bill Bryson talked about this in The Body; the tl;dr is that, yes, with the right scent, humans are as capable as dogs when it comes to tracking something down.

Bill Bryson talked about this in The Body; the tl;dr is that, yes, with the right scent, humans are as capable as dogs when it comes to tracking something down. The study he cited had humans on all fours, nose to the ground, searching out chocolate which had been moved across a field. The unstated bit of this is that humans are probably less good at scent differentiation, which is another factor in olfactory "capability," but not strictly the same as the ability to track a scent (though you could argue that if you're more likely to follow a subtly wrong scent, you're less capable -- something not captured by the studies which have looked at this, I don't think).