Smell. One of the most important senses. It can alert us prior to being able to see or hear anything.
“Smell, like taste, is a chemical sense detected by sensory cells called chemoreceptors. When an odorant stimulates the chemoreceptors in the nose that detect smell, they pass on electrical impulses to the brain. The brain then interprets patterns in electrical activity as specific odors and olfactory sensation becomes perception — something we can recognize as smell. The only other chemical system that can quickly identify, make sense of and memorize new molecules is the immune system. But smell, more so than any other sense, is also intimately linked to the parts of the brain that process emotion and associative learning.”