|Bacterial build-up on the human|
The 100 trillion microorganisms that make up the human microbiota are responsible for all kinds of important process, from digestion to synthesis to protection against disease. Microbiota composition is dependent on a bunch of factors, including age, diet, genetics, the environment, and who we interact with. Your mouth contains 700 varieties of bacteria, and these are influenced by the people you keep close to you, according to a new open access study published in Microbiome yesterday.
The results basically showed that intimate partners have more microbial communities in common than strangers do. And all it takes is 9 intimate kisses per day to do it. An intimate kiss doesn't increase the amount of bacteria in your mouth, though, likely because both partners are trading similar amounts of bacteria. So while you're receiving 80 million bacteria from your partner, you're also passing on approximately the same amount.
Intimate kissing is involved in the romantic courtship rituals of 90% of human cultures. It's also unique in the animal kingdom to humans. Based on their results, the authors posit that kissing may have an evolutionary significance: kissing maintains a consistent oral microbiota between partners, as do other factors like a shared lifestyle and diet. They can't speculate any further than that, but based on the importance of the human microbiome, it stands to reason that sharing the same bacterial species as partners, friends, and children was evolutionarily crucial.