mike and alanna goes back to london. dr.her calls them. >> i can't wait to tell you the results. i'm delighted to tell you, that in your brain, mike, we found activity in that brain region associated with intense romantic love. so, you're both in love and you're bothly deeply attached to each other inspect. >> okay, good. she's craig over here. you can't see the tears. >> that's so sweet. it's so sweet. >> i was worried about you. the last results made me rally sad. so, this is lovely. >> timely, my brain is behaving itself. >> here's mike's brain. test one. test two. and a very happy test three. >> reporter: what is the secret to lasting love. >> one guy gave us a piece of advice, you got to marry the right person. >> reporter: have you? >> of course, the response has to be, have you married the right person? >> yes, absolutely. >>> when we come back, just a kiss, just a touch, even just a thought, do this to matt. we meet the man who's literally paralyzed by love. we speak value. and people like what we're saying. about ho

and alanna boyle thought he was madly in love when she accepted. both felt in love at their 2008 wedding. so, as they started their life together, mike was really alarmond to hear that 50% of marriages end in divorce. >> the thing that really kind of struck me, everyone who goes to the altar are in it for the long haul. but yet 50% fail. how do we stay together for life? >> reporter: to find out, mike clear had a radical idea. they would put their young love to an extreme test. >> we're going to quit our jobs. >> reporter: traverse the longest road in the world. the pan american highway.

alanna lavine, a practicing pediatrician and spokesperson for the american academy of pediatrics. good evening. good to have you here. >> thank you. >> you say that this is, while shocking, not surprising to you. why? >> it's true. i'm seeing it in my practice. i'm seeing young girls coming in not knowing what their breast buds are. they are not realizing what it is because it is earlier than it was in the past. >> it is said to be found as young as 7. what are parents to do? what is your best advice based on your experience? >> the first thing parents need to do is understand this is happening so they can talk to their children beforehand so before breasts start to develop the children know what's happening to them. the second thing parents can do is really encourage a healthy lifestyle for children. we are not sure 100% of all the causes but clearly they are multifactorial but weight plays a role, genetics, the environment plays a role. as parents we really want to do our best to provide a healthy lifestyle. >> you're talking about exercising, eating healthy, staying away from j

7-year-old alanna says it best. >> you get to pet animals. >> reporter: and it's not just loud sheep.deer, donkeys, llamas, even a kangaroo and a zebra. with hundreds of hands reaching out, we wanted to know what kind of germs could be picked up. with the help of north dakota state university, we tested 12 areas of the petting zoo. a lab student swabbed railings, feed dispensers and kids' hands. even j.j. the resident camel gets in on the action, with a swab to the south. >> there's been some e. coli at the petting zoos. >> reporter: julie garden-robinson, a food and nutrition specialist, with ndsu, says that petting zoos are usually safe places. but the elderly and young children could be more vulnerable to the bacteria found at them. >> be sure the children don't bring the sippy cups or the pacifiers to the petting zoo. that could introduce contamination. >> reporter: petting zoos themselves have the power to prevent many outbreaks. every state has its own rules and regulations for the number of animal vaccines needed. wally says he spent close to $2,000 to make sure his animals wer