Love is in the air this week as we approach Valentine's Day on Sunday. But is love also in your microbes? In this edition of grant money . It turns out the sexual love and attraction makes up cutting edge research into the human microbiome. Joining me is tran31. -- Tran31 -- tran21. Each of these populations of these critical microbes for -- form and mycology. We are learning startling differences about ourselves. You have to think that you are just one being. You can see your own reflection. It's a surprise but nature does not see you that way. When you look at yourself in the mirror you see a biological evolution of everything that make you one thing. Those cells that you see in the mirror are partly your own but the March larger majority an actual numbers are microbes. The number of microbial cells that are part of you outnumber your own personal cells by 10 to 1. We knew there were microbes that were part of being human but we thought they were just kind of hangers-on. Just like they were a scaffold and wanted to hitch a ride on the. They like being with us and mostly did us no harm. They did have some slight good now and again. Mostly they have never been considered deeply relevant to our health or how we became who we are in an evolutionary way. And that is changing out. Completely. We cannot live without them. We provide them habitats that they want. But even more crucially from our perspective we cannot survive without them. As we do more research we are finding out there are absolutely critical linkages between microbial populations and our metabolism, how we regulate glucose, obesity, how much weight do we gain, whether or not we do gain weight. Crucial elements of our immune system are linked to these microbes. Since we are exploring the science of love on this Sci-Q let's talk about the microbiome and what we think we have learned about how it might influence our romantic partners. People to our romantic partner share a huge amount of microbes and they would have to all the time. But do they share similar microbiome before they become a couple? The answer is yes and no. These microbes are critical for metabolism and immune function. That is the linkage towards why these microbes are important for our romantic entanglements. These microbes influence our moods and our social choices. We can do it in two ways. They did a really neat study about intimate kissing. Those couples that kiss intimately, deeply, and often share microbes. Every time you kiss your trading 100 million microbes. That is a good thing. It sounds creepy but it is good. What they expected to find was both sets of microbes would overlap with people that share deep kisses based on transfer. They did find out that is true. But they also found out when they tested the partners to see who was really attracted to whom, the people whose sets of microbes inside the mouth tended to match much more than random between the people that found themselves attracted. What we do know is these microbes don't just exist anywhere. They are giving off metabolic products and have a lifecycle of their own. Those metabolic products are circulating through our mucosal membranes and circulate around and get to our brain and change our-, centers. This is true, not science fiction. There was an experience that involve sweaty T-shirts? Yes. This was a good one as well. They got a group of volunteer women to go ahead and smell 10 sweaty T-shirts that men had worn. They didn't know anything about the men. They didn't know whether they were tall, short, successful, good-looking, age, or any of those factors. What they wanted the women to do was determine for themselves whether they felt that the older was basically pleasant, neutral, or disgusting. So they asked him to go ahead and evaluate them. At the same time they took a measurement of the men and also of the women participants. They were looking at a special form of immunological marker. The name of which is unimportant. It is a marker of immune function, robust immune help. What they found, which was predictable and reliable, is that women chose as a good smell men whose immune systems were both healthy but different from theirs. There is an important evolutionary reason for that. we know the most important aspect for survival is immunocompetent. So it evolutionary terms you want the. That's the best chance of survival. It is not so much muscle strength or speed. What really counts is immune status. Protection against pathogens and bad bugs. You want your child, your fetus to have the best chance possible. That is immune status. If you take a healthy immune system from one person and at the variety of another healthy immune system that's different, you get the combination. You get stronger. It is stronger in evolutionary terms and the mixing of those complexes yield a single, more robust immune system. Doctor Miller some scientists say a microbiome as an indicator of attraction is exaggerated. The science behind these claims is early. It is good science to indicate that there are studies showing that there are fractional effects that can be measured and that more studies need to be done. We do need to be careful. In science a lot of times you leap to conclusions that needs to be adjusted. We are only at the very beginning of an enormous leap forward in medical practice and understanding ourselves. It is certain that as we explore more and greater depth about the microbiome about its relationship with ourselves, the things that we find out we will be able to use to improve our life. Things like diabetes see -- diabetes, obesity, etc. We have begun to use transplants of these microbes to try to affect a positive health change in other people. This has moved beyond the experimental stage to genuine, reproducible treatment for inflammatory bowel disease. It is now a preferable treatment. And we will move onto other things that are active experiment on obesity and many other areas. There are great things in our future, medically speaking and many surprises ahead of us. So if we are attracted to someone on Valentine's Day we were blame it on our microbiome? I'm going to tell my wife I love her microbiome and she's going to say couldn't I just have had a bracelet? [Laughter] Print 17, thank you so much.
Did you know you may be attracted to a romantic partner's microbes?
It's possible, according to Dr. Bill Miller, author of "The Microcosm Within: Evolution and Extinction in the Hologenome," a book examining immunological factors in evolution.
He told KPBS Midday Edition that a study found couples who kiss "deeply and intimately and often" not only share microbes — an expected and beneficial outcome — but also were attracted to each other's microbes before they became a couple.
"When they tested out the partners to see who was really attracted to whom, the people whose oral microbiomes, the sets of microbes inside the mouth, tended to match much more than random between the people who found themselves attracted," he said. "How could that possibly be? What we know is these microbes don't just exist, they're giving off metabolic products, they have a life cycle of their own."
He said those metabolic products make their way to our brains and influence our attraction.
"It sounds creepy, but it's good," he said.
A microbiome describes the population of microbes — all of the living organisms that inhabit our bodies, including healthy and unhealthy bacteria — that each person carries.
"You look in the mirror and see yourself, and you have to think you're one being," Miller said. "But nature doesn't see you that way."
He said the majority of cells you see when you look in the mirror aren't actually your own, but are instead microbes.
"We cannot live without them," he said. He said new research is finding the links between our microbiomes and our metabolism, blood sugar and our immune system.
And, he said, our relationships.
"What we're finding out is that they're giving us hidden cues," Miller said. "This is still new research, but what we're finding is our microbes are giving off chemical signals that determine our reaction to social circumstances and even romantic entanglements."
Sci-Q is a monthly series on Midday Edition, and KPBS listeners are invited to join in on the fun. If you have a scientific topic you'd like to explore or a question you want answered, contact us on Twitter @KPBSMidday using the hashtag #Sci-Q.
