We're not purporting this is foolproof, but researchers from DePauw University in Indiana have concluded that you can guess the chances your marriage will last based on what you and your spouse looked like in old photographs.

LiveScience.com reports that people who are pictured smiling in old photos are more likely to be in a successful marriage than the grim and sour-faced.

The first test: The researchers examined the college yearbook photos of a group of people and rated their smile intensity from one to 10. To judge this, they looked specifically at the stretch of two muscles: the one that pulls up on the mouth and the one that creates wrinkles around the eyes. Of this group, no one who fell in the top 10 percent of smile intensity had divorced, while almost 25 percent of those in the bottom 10 percent of smile intensity had ended their marriage.

The second test: People older than 65 provided photographs from their childhood. The average age of the child in the photo was 10 years old. Again, the researchers scored each person's smile. The results? Only 11 percent of the biggest smilers had ever been divorced, but 31 percent of those who smiled the least had a broken marriage.

The takeaway: People who frown or have a grim expression in photographs are five times more likely to get a divorce than people who smile. Most interesting, the researchers found a connection between photos taken when people were young and marriage outcomes that sometimes occurred much later in life. "It feeds into this idea that what's occurring earlier in our lives in terms of our present situation and our mental state can predict things that occur decades later," study leader and psychologist Matthew Hertenstein told LiveScience.com. "Showing the continuity in who we are is really important."

But be forewarned: As fun as this easy little test is, even the DePauw researchers caution not to draw conclusions. "Maybe smiling represents a positive disposition towards life," Hertenstein told LiveScience.com. "Or maybe smiling people attract other happier people, and the combination may lead to a greater likelihood of a long-lasting marriage. We don't really know for sure what's causing it."

Here are some other possible explanations:

• People who smile more often tend to attract more friends, and a larger support network makes it easier to keep a marriage healthy and strong.
  
• People who smile when instructed to do so by a photographer may have more obedient personalities, and that could make marriage easier.
  
• People who smile in photographs have a generally happier disposition and get along with others better.

--From the Editors at Netscape