Scientists say that we laugh when someone tickles, or hear a good joke instinctive reaction, but learns to cry. Even though it may sound incredible, when babies are born must "learn" to cry.
Unlike laughter that is innate, crying in response to grief, or the eruption of emotions that are so common in babies learn after birth.
A few moments after the birth of the baby crying from the shock due to the arrival of the world and reflecting the need for oxygen, experts say.
Dutch researchers asked the 16 volunteers, half of whom were deaf from birth, to the sounds of them show different emotions, from sadness and fear, through relief, and happiness without using words.
Recordings of their performances then were allowed a group of 25 normal volunteers who hear, and they were asked to identify emotions. It turns out that the only laughter and the sounds that conjured up a sense of relief with no errors are identified, even when it comes to recordings of deaf people, according to a study published in the journal New Scientist.
On the other hand, the sounds that need to present a crying or sadness second group is much easier to recognize when they were in terms of images of people who hear normally.
Since half of the respondents had never heard human laughter, but there were no differences in their interpretation of laughter in relation to the interpretation of people who hear, the scientists concluded that the inherent laughing and crying to learn through experience.