Scientists have discovered, that when we shake hands with someone, we immediately afterwards sniff our hands to convey information from the newly picked up scent:

You won't believe you do it, but you do. After shaking hands with someone, you'll lift your hands to your face and take a deep sniff. This newly discovered behaviour – revealed by covert filming – suggests that much like other mammals, humans use bodily smells to convey information.

We know that women's tears transmit chemosensory signals - their scent lowers testosterone levels and dampens arousal in men - and that human sweat can transmit fear. But unlike other mammals, humans don't tend to go around sniffing each other.

Wondering how these kinds of signals might be exchanged, Noam Sobel and his colleagues at the Weizmann Institute of Science in Rehovot, Israel turned to one of the most common ways in which people touch each other - shaking hands. "We started looking at people and noticed that afterwards, the hand somehow inadvertently reached the face," says Sobel.