It's a proven factthat a bloodhound dog can track a human sent that has past a given area and trail it up to a week old. Also a fact that the longest trail of a human by a bloodhound was over 50 miles. How old do you think that trail was? These animals do exist on this big blue marble (earth) and I personally believe after hunting all my life deer are NO different. They may have a different degreeof a nose maybe's it's not quite as powerful but still you have to compare with the facts of some other species to put things into perspective. I've witnessed Whitetail given the optimal condition's pick up a none moving stationary human (being myself) pick there sent up at over 500 yards. Something that if you learn now will be the most truthful thing you could ever learn in your journey of becoming a great whitetail hunter is "A deer's eyes can fail them, and sometimes thier ears, but NEVER, thier nose". Good luck in your journey.