I'm back now... expect some Catalan blogging for awhile. For starters, here's one thing most people surely take notice of but few reflect on when they visit Mediterranean countries -- people make out in public a lot. Not just wimpy PDA like holding hands and giving each other Eskimo kisses: I mean like a guy smacking and grabbing his girlfriend's ass, locking lips for minutes at a time at the entrance to a crowded crosswalk, and (in Rome but not Barcelona, as far as I can tell) using public benches like teenagers here use the floors of their parents' closests during parties. Nothing you'd see in the Puritanical northern European countries and their offshoots.
Again, few people reflect on anything, but those who do opine on such matters when they visit foreign lands usually overly romanticize the place -- thus, Mediterraneans make out in public more than we do simply because they're more passionate, more driven by the carpe diem credo than we sterile, rain-cheque-promising Northerners. But like many other attempts to escape one's ambient boredom by latching on to an exotic culture, this belief is completley misguided. Is there a kernel of truth to it? Sure. But why would being a passionate, day-siezing individual compel one to do so publicly and seemingly indefinitely? As with most other public displays, this is one way of signaling important information to one's conspecifics: in this case, "Back off fuckers, she's mine." Of course, more of this proprietary behavior comes from males (who demand their mates wear signs of being taken -- rings, hair-coverings, etc. -- more often than vice versa), since for a random male, it's not as if there's a horde of females waiting to poach him from his current partner.
That leaves us with two not mutually exclusive possible explanations. First, it may be that Mediterranean males are more willing to poach a taken female, such that the current boyfriend or husband feels a greater threat and so takes more drastic measures to frighten them off (lip-locking rather than putting his arm around her). And second, it could be that Mediterranean females are more willing to run around on their partners, so the boyfriend or husband must take more drastic measures to ensure she doesn't act on this impulse. Presumably, there is little variation in male impulse to cheat if they felt they wouldn't get caught, so we don't see as much female variation in proprietary behavior toward their mates. I'll have to dig it up, but the only journal article on personality and promiscuity that I've read suggested that Extraversion and Neuroticism had no predictive value on infidelity, but that (low) Agreeableness and (low) Conscientiousness did; or in Eysenckian terms, high Psychoticism would have predictive value. (Steve once speculated that Extraversion was behind "the jealousy belt.") Italy and Greece are both high-ish in Psychoticism, but Spain is low, so the correlation clearly isn't perfect. Also, better data on actual rates of infidelity would be better than using personality traits as a proxy.
In any event, the real reasons behind Mediterrean Mega-Makeouts likely have little to do with a greater zeal for life, but instead belie a more tense undercurrent of suspicion and jealousy. A good rule of thumb, then, when visiting another country is to translate the sappily romantic spin the guidebook gives you into a more cynical take, and you'll be pretty close to the truth.