科学英语：人们握手时会传递化学信号

Limp or firm, your handshake conveys subliminal1 social cues. Now, research reveals it also transmit

Limp or firm, your handshake conveys subliminal1 social cues. Now, research reveals it also transmits chemical signals that could explain why the greeting evolved in the first place. In the study, published in the journal eLife, scientists from Israel's Weizmann Institute of Science found that people use the touch of a handshake to sample and sniff2 signalling molecules3. During the experiment, around 280 people were greeted either with or without ahandshake. They were filmed using hidden cameras and observed to see how many times they touched their face. One finding of the study was that people constantly sniff their own hands -- keeping a hand at their nose about 22% of the time. Subjects greeted with a handshake significantly increased touching4 of their faces with their right hand. However, this only seemed to be the case when the subject had been greeted by aperson of the same gender5. To check that the observed face-touching was being used as away to subtly sniff the hand used in handshaking, subjects were fitted with nasal catheters to measure airflow. They found that when ahand was in close proximity6 to the nose airflow through the nasal passages doubled. In other words, the subject was sniffing7. ""It is well-known that we emit odours that influence the behaviour and perception of others but, unlike other mammals, we don't sample those odours from each other overtly," says Professor Noam Sobel, Chair of Neurobiology at the Weizmann Institute of Science.