Your nose can recognize more than 1 trillion different smells.

In 2014, Dr. Andreas Keller and his team at Rockefeller University decided to test how good the human nose really is. They gave 26 people different mixtures of 128 unique scent molecules to see if they could tell them apart. Based on these tests, they calculated that the average person can distinguish at least 1.72 trillion different smells.Inside your nose is a small area called the olfactory epithelium. This spot contains about 400 types of scent receptors that act like tiny locks. When a smell molecule fits into a receptor like a key, it sends an electrical signal straight to your brain. This happens in a part of the brain called the olfactory bulb.The olfactory bulb is special because it connects directly to the parts of your brain that handle memory and feelings. These areas are called the amygdala and the hippocampus. This is why a single sniff of a crayon or a certain flower can suddenly make you remember something from years ago.The researchers believe the 1.72 trillion number is actually a low estimate. They only used a small group of molecules for the test, and there are many more in the real world. Your genes also play a role in how you smell. Some people have different sets of receptors, which makes them better at picking up specific scents than others.