PARIS (Reuters Life!) - If around half of all modern marriages end in divorce, how do a young couple find out whether they are in the 50 percent who stay together?
Newly wed Londoners Alanna and Mike Clear quit their jobs, remortgaged their home and set off on a 20,000-mile trip by motorbike and sidecar to explore their own marriage, while asking people from Alaska to South America about relationships for a documentary called "Going The Distance."
They also consulted the experts before they set out.
Biological anthropologist Helen Fisher and neuroscientist Lucy Brown of Rutgers University, New York, scanned their brains to see if neurological responses showed they were "in love."
Geneticist Eric Holzle, founder of DNA-based dating service scientificmatch.com, took DNA swabs to assess their genetic compatibility, while relationship therapist Terry Sterrenberg of the Gottman Institute spent a day analyzing how they interact.
"When we meet people on the road, they are dumbfounded that we left our jobs and remortgaged our house," Mike said in a telephone interview with Reuters.
But family and friends back home were supportive of their dream. And after Alanna's "existential crisis" when browsing through racks of expensive china to compile a wedding list -- "I didn't want a 60-pound plate," Going The Distance was born.
The two 30-year olds eventually asked friends and family to leave the china in the shop and buy brake cables or nights in hotels as wedding presents instead.
Clad in white, red and black "Going The Distance" boiler suits -- "they make us approachable, and having a uniform gives us a sense of purpose" -- the pair set off from Anchorage, Alaska three months ago to find out what makes a marriage work.
Now around half way through the six-month ride down the Pan American highway, they are interviewing couples -- from swingers to Mormons, nudists to nature-lovers -- and relationship experts, including John Gray, author of relationship bestseller "Men Are From Mars, Women Are From Venus,'" along the way.
They have had a friendly reception so far, thanks to their eye-catching bike and sidecar, the Russian Ural "Tourist T."
Although a 20,000 mile road trip in a car would undoubtedly be more comfortable, the couple say the motorbike gives them an easier entree into people's hearts.
"The Wallace and Gromit effect has been amazing -- the bike gets people laughing and talking and it makes us seem unintimidating," Alanna said in reference to the animated British film characters and noting just one downside -- the lack of air conditioning.
She also loved the idea of "taking the ultimate symbol of male freedom and sticking the wife on the side."
So far planning the trip and getting on the road have been exhausting, but teething problems with their motorbike, struggling to get interviews and remembering to eat before blood sugar plunges and tempers fray have been the main challenges.
But the going is about to get tougher as they cross the border into Mexico, embarking on the Spanish-speaking leg of their journey with only Mike's conversational Spanish.
"Until now the most important thing has been the people we've met -- now it's more about us two, and traveling -- the people we meet will become more incidental," Alanna said.
And there is one more obstacle to overcome. When they arrive in Ushuaia, the world's southernmost city, in December, their families will be waiting to celebrate Christmas with them.
But the couple will also open an envelope containing the results of the three tests: if the experts think their marriage will go the distance, they plan to renew their wedding vows.
And if not? "We'll try to brush it off, but I think it will niggle," said Mike.
They are, however, already armed with tips from the experts that should help them negotiate any bumps in the road ahead.
And couples they have met on the road have taught them an even more valuable lesson: "If you ask couples about love, you get love. The warmth and intimacy we've seen has been amazing. It's definitely strengthened our relationship," said Alanna. "I don't know if we know what love is, but we can recognize it when we see it."
Editing by Paul Casciato