A sign of genetic trust. Your body spends so much energy trying to keep unwanted microbes out, that for you to combine your oral
environment with someone else’s is like two countries just opening borders and letting the populations mingle. The problem is, humans are not very selective about who they kiss. Have some alcohol, then add another human with symmetrical features and signifiers of
youth and willingness to mate, and kissing will occur. Now the problem is not what most germaphobes fear- systemic illness, nay my friend, the problem is bacteria
associated with periodontal disease and caries. Lets say you have a healthy mouth- you brush and floss daily, you keep the sugary drinks down- then you go to a party, get drunk, and make out with Mike
the Man whore, Bam! Unbeknownst to you, Mike has generalized chronic moderate periodontitis and rampant decay. Your mouth is then flooded with bacteria
associated with these conditions. These bacteria are highly virulent and greatly increase your risk of coming down with the same oral diseases. Oh, and your mouth will not “go back to normal” after a few days, Oh no my friend, these bacteria have been INTRODUCED! They are reproducing like crazy- setting up nice cozy homes in biofilms and gingival sulcuses! Because of your impulse to pass your genes on with what your primitive “ID” considers a good partner, you have allowed the equivalent of an ecological disaster to start
in your mouth. Hope you know a good periodontist!