system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why do humans (and other animals) enjoy kissing the things they love?

When it comes to partners, pets, trophies, etc. Why/how did we develop the desire to put our lips on things we are attracted to?
gpt
There is a hypothesis that the behavior arose from mouth feeding (think birds feeding their young) but we don't know for sure. 90% of human cultures have some form of kissing, so there is evidence that it is an inmate human characteristic.

There is also evidence that kissing helps us detect another person's MHC genes which is a genetic compatibility indicator (research suggests that we are attracted to others with different MHC genes as our own).

Why we kiss our dogs and other things? Habit, and learned behavior most likely. Kissing releases oxytocin and serotonin and we learned that that feels good so we kiss things we love.