If you thought your dog's sense of smell was good, think again.
Dogs have a sense of smell that is at least 40x better than ours! That's right: dogs can smell in parts per trillion, while we can only detect odors in parts per billion.
Dogs have 60 times more olfactory receptors than humans do, and they can detect pheromones (scent signals) from miles away—and they use those signals to communicate with each other. Dogs are also capable of detecting smells from urine samples that are over a month old, which means that if you've got a dog in the house, it probably knows about all your secrets.
So next time you think your dog is being annoying and sniffing everything, remember: it may be because they're just trying to figure out what's going on in your life!