Today, Earth welcomes back Cmdr Chris Hadfield who touched many people, not only Canadians with his tweets and Youtube videos from board of the International Space Station (ISS). One of the last things Cmdr Hadfield did was to post a very cool rendition of David Bowie's Space Oddity. The music was recorded on earth and the singing on board of the ISS. The text is slightly altered from the original and rarely has this song been so relevant than here with Cmdr Hadfield leaving the ISS just a few hours later - looking one last time at Earth from that perspective ...
I must admit, it brought a few tears to my eyes. The video was powerful - the music has so many associations for me, it was a particular moment in time that would never come back (you can do something for the first time only once). So why were there tears?
Crying has been one of the interesting riddles - what is the function of crying? What is the evolutionary perspective on crying? Is crying good for you or bad for you?
As it turns out, there are no easy answers. Darwin already was not completely sure what do with crying. Quote from Darwin (1872)
(p. 172) In considering how far this view is probable, we should bear in mind that the eyes of infants have been acted on in this double manner during numberless generations, whenever they have screamed; and on the principle of nerve-force readily passing along accustomed channels, even a moderate compression of the eyeballs and a moderate distension of the ocular vessels would ultimately come, through habit, to act on the glands. We have an analogous case in the orbicular muscles being almost always contracted in some slight degree, even during a gentle crying-fit, when there can be no
So the idea here is that forceful crying in the infant leads via mechanical reasons to the secretion of tears. Over time particular situations get associated with this type of fit, which in turn gets more and more controlled in the adult and so crying when adults are sad is a sort of remnant of this process. You can read the argument in more detail here.
Since then many researchers have studied the mechanics and chemistry of crying and tears. It is still a complicated story though ... is it satisfying? Can it cope with sentimental crying? What about crying for joy?
One of the key researchers on crying is Ad Vingerhoets from Tilburg University. Here is a brief article from the Guardian that refers also to Ad's recent book Why only humans weep.
I have also tried my hand at the topic, but then - Ad's books are probably the best place to start ...
In the meanwhile - Cmdr Hadfield answers the question what happens to tears in space ...
Darwin, C. (1872). The expression of the emotions in man and animals. London, UK: Murray.
Kappas, A. (2009). Mysterious tears. The phenomenon of crying from the perspective of social neuroscience. In: Thorsten Fögen (ed.), Tears in the Graeco-Roman World (pp. 419-438) , Berlin & New York,: DeGruyter.
Arvid Kappas is Professor of Psychology at Jacobs University Bremen. He has been conducting research on emotions for over three decades in the US, Canada, and in several European countries.