Re: why closed eyes when kiss?

Dr. Hartunian,

I loved the question, but was unable to find a theory that explained the phenomenon to my satisfaction. I think, however, that a slight modification of your suggestion of maintaining a "passionate state of mind" leads to a plausible evolutionary argument. First, by shutting out other stimuli (e.g. closing the eyes), animals are better able to focus their attention on one sensory modality (similar to your proposed focus on passion). Indeed, the brain may even try to do this internally as well (Weissman, et al.: 2004 is an example). If the act of kissing was somehow imporatnt to fitness, then focusing one's sensory attention on it may have been an adaptive strategy.

The question then becomes, was kissing of some crucial evolutionary importance? One source to examine is the literature on primates. One utility for kissing in numerous primates is to signal reconciliation after a conflict (de Waal: 2000), and I have seen photos of primates kissing with both open and closed eyes. Kissing can also strengthen social ties between individuals, much as other forms of physical contact. In a tightly knit group, a behavior which leads to more salubrious interactions could behoove all members (via lower stress levels, increased food sharing, etc). Therefore, paying it the utmost attention may increase fitness. We could also speculate that closing the eyes signals increased trust (for lack of a less anthropomorphic term) between individuals, further facilitating reconciliation, or tighter social bonds.

Undoubtedly other theories could explain the behavior, but this is certainly one way in which an eyes-shut kiss could have been beneficial in an evolutionary context. Thanks so much for a great question and let me know if you turn up any other interesting leads.

Best of luck in your teaching and research,
Jim

References:
Weissman, D.H., L.M. Warner, and M.G. Woldorff, 2004, "The Neural Mechanisms for Minimizing Cross-Modal Distraction," Journal of Neuroscience 24: 10941-10949.

de Waal, F.M.B., 2000, "Primates--a natural heritage of conflict resolution," Science 289: 586-590.