Question: Hey Murray! :3 I just read your profile and found out you like Muse!? I love Muse! :D Anyway, i have a science question for you...Why do we cry when we're unhappy? Thanks. :')

Murray Collins answered on 16 Mar 2011:

Hi! I often have muse on my ipod, especially on the way in to work in the morning, or in the gym. Gives me lots of energy. 🙂

Very interesting question this one, why we cry when we are unhappy (and also why we cry at all). There is no one answer to this. But I think using at evolutionary perspectives on human behaviour and psychology give us a useful way to think about the problem. Humans, like other primates, especially the other apes, have many different ways of communicating with one another.

In addition to the way we make signals with our bodies (body language) humans obviously have developed linguistic abilities – this means we can talk directly to one another and explain how we feel and what we want to do. Amongst the apes I think this is a derived trait, which means that it was something that we did not share with our last common ancestor, because none of the other existing apes can talk.

I think that the type of crying that us humans do is unique to our speciesMATOMO_URL ///So I think that maybe like language, crying developed as a way of communicating our emotions with other individuals in our group./// I suspect this developed before language became very complex and before it was easy to say ‘please hug me, I am feeling very sad’. Instead you see someone crying and may want to give them comfort, especially when you are related to that person or are good friends with them. Just because we now have complex language, however, that doesn’t necessarily mean that crying isn’t useful to us, nor that it will disappear from human behaviour in the future. First of all it is clearly a very useful means for children to communicate their feelings, although the reasons we all cry are probably more complex than just being unhappy. So crying, for whatever reason, definitely gains us attention amongst our group. Crying for happiness is probably part of the same display mechanism, and could have helped groups and pairs of people in the past (but also now) to develop stronger social bonds.

Social bonds are very important. Our abilities to communicate effectively with one-another can determine how effective we are in getting along with one another. This affects how efficient we are working as a team. In the past, as with the present, better teams would have been more efficient at finding and sharing food resources, and beating other groups to get the best places to live etc. So there was probably a strong pressure on us as a species to be good at communicating and cooperating.

However, everything I have said is also complicated by another major factor – culture! Our behaviour is moderated by our culture. In many cultures men will do everything they can to never be seen crying as it is seen as feminine or a sign of weakness for example. Maybe because it is something that children do, and shows lack of control over emotions. And in certain cultural contexts it is bad for a man to be governed by his emotions, or even display them, especially in public! So to some extent we learn when to cry, or when not to cry.

But my original answer stands, that crying developed as a means for humans to better communicate with one another, which helped us to form better bonds, and work better together.

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*I put a star above because I said I though crying is unique to our species. Scientists generally are reluctant to say what kind of emotions other animals including other apes have, or whether they have any at all. Using descriptions of human emotions to describe emotions in other animals would mean making assumptions that they are like us, and would be ‘anthropomorphising’. Blimey that really is a long word! Having said that though, animals like other apes do make some quite distinct noises when they are in some form of pain or distress. I heard chimpanzees screaming in the forest in Gabon often, and certain sounds are associated with certain behaviour (like being attacked, or seeing a predator). So maybe chimpanzees have emotional displays that are somehow similar to our human crying.