Dogs can smell when people are stressed.
Dogs have been trained to sniff drugs and bombs, but their most impressive olfactory feat might be their ability to smell when people are stressed. Though this likely comes as little surprise to dog owners, who are often well acquainted with their canines’ emotional intelligence, it’s still an impressive skill. A recent study showed that acute psychological stress produces changes in the odor profile of human sweat and breath, which dogs can detect with 93.75% accuracy. This was determined over the course of 720 trials in which samples were taken before and after people performed a high-stress task that increased their blood pressure and heart rate. The most skilled pup in the trials was able to detect the difference between samples at 96.88% accuracy.
To say that dogs’ sense of smell is stronger than ours would be an understatement, even though the human sense of smell is better than was long believed. Some dogs have hundreds of millions of smell receptors in their noses (humans have 5 million to 6 million), and the olfactory bulb in their brain is 30 times larger than ours. Overall, dog noses are thought to be 100,000 times more sensitive than ours, which is either a blessing or a curse depending on what you’d be smelling at any given time.