Poets, philosophers and other careful observers of the human condition have long pondered the question that troubles the heart of romantics everywhere — can true love last forever?

Now science has provided the answer to that question, and it is not going to please the more sentimental among us. New research in the field of brain chemistry has shown that the "truly, madly, deeply" feeling of falling in love doesn't last more than a year. And yes, they have proof.

According to an article published by a group of Italian scientists in the journal Psychoneuroendocrinology (I dare you to try to pronounce that), that crazy, euphoric feeling we experience in the early stages of a romantic relationship seems to have a biological basis, one that can be measured and monitored over time.

The researchers tested the blood chemistry of 58 couples who were in the early stages of a new romantic relationship and they found that all of the couples (both the men and the women) had much higher than normal levels of a protein called nerve growth factors (NGF). It is believed that this protein has a direct relationship to the feelings of euphoria and emotional dependency associated with falling in love.

A year later, the 39 couples from the original test group who were still together were retested. By that time their NGF levels had dropped back to normal, the men had stopped remembering to put down the toilet seat, and the women had stopped shaving their legs every day.

OK, I made up the last two items, but I'll bet they're true. And really, no one over the age of 21 is going to be surprised by these findings.

That out-of-your-head, butterflies-in-your-stomach state of infatuation is not something that can be sustained over a long period of time. We're just not built that way, and really that's probably for the best.

Infatuation is necessary to get people to stop their busy lives and notice the opposite sex long enough to keep the species from dying out. But if that crazy-in-love state lasted forever, nothing productive would ever get done. People would be walking around dopey, love-drunk, and unproductive from their teenage years on. Houses wouldn't get built, crops wouldn't be sowed and sitcoms wouldn't be filmed. Society would fall into a slothful form of chaos, and the survival of our species would be threatened from a different angle.

Luckily it doesn't work that way, and by the time a hapless couple comes to their senses they are often so connected to each other that they decide to stick it out and see where things go.

I'm no Dr. Phil, but I have my own theory about love. Love is a complex word with many shades of meaning, but when it comes to romantic love I think there are at least three distinct emotions that get lumped together to describe the experience — infatuation, lust and friendship.

Infatuation is what is most often meant when someone says they've "fallen in love," and it is the temporary euphoric state of mind that is the subject of the research on blood chemistry mentioned above. I don't think I have to explain lust to anyone, and for most couples that feeling also tends to diminish to some degree over time.

Friendship, or companionship if you will, is the one element of a love relationship that can, potentially, go on indefinitely. People who can enjoy a conversation or a bike ride or a walk in the park after being together for a few decades are the ones who have a chance to make it over the long haul, and they should count themselves fortunate.

Hallmark and the jewelry stores might disagree with me on this point, but you can't trust them — they're only after your money. I'm only here because I care.