Scientists have been struggling to find out the reason behind blushing (脸红) . Why would humans evolve (进化) a【41】that puts us at a social disadvantage by【42】us to reveal that we have cheated or lied? Charles Darwin pointed out that【43】all people of all races blush, animals do not. When it came to explaining the reason, he was【44】a loss. That has not stopped others from trying. One【45】is that blushing started out as a way to show we obey authoritative members of the group. Later, as our social interactions became【46】complex, it became involved with higher, self-conscious【47】such as guilt, shame and embarrassment. This would seem to put individuals at a disadvantage, but blushing might actually make a person more【48】or socially desirable. 【49】that women blush more than men, one university researcher suggests that blushing might have evolved as a way for women to【50】their honesty to men so as to win their support in raising children. Some zoologists also think blushing could have emerged as a way to foster trust. 'If you were to go hunting【51】a stone-faced partner, you could never【52】what he wants.' He says. Once blushing became【53】with embarrassment, anyone who did not blush might have been at a disadvantage because we are【54】likely to trust someone who appears never to feel【55】about anything. (41)