Sex usually begins with a kiss (although if you have no one to kiss you can always go solo with your cell phone). Humans like to kiss because we have lips that are DESIGNED for it: We are the only animals with lips that purse outward. But we're not the only primates that kiss--some of the apes do too (although we're not sure about machines).
Yet anthropologists don't think it's instinctive--they think it's a learned behavior, because although most cultures kiss, not all of them do. In fact, the Romans, who conquered wide swathes of Europe, introduced kissing to many non-kissing societies. While kissing can give you cavities in your teeth, it does get two people close enough to smell each other, which having sex (depending on how you do it) doesn't always do. Women instinctively prefer the scents of men whose immunity-coding genes are different from their own, since mixing genes produces babies with stronger immune systems.
Dopamine, which brings out feelings of desire and reward, spikes in response to new experiences, which may be why kissing someone for the first time feels so special. Dopamine can even lead to sleeplessness and a loss of appetite--classic "lovesick" signs. Dopamine is produced in the same part of the brain that affects addictive drugs like cocaine. In men, a kiss brings forth the "love" hormone oxytocin. Women are suffused with this hormone after giving birth--men get it from holding and playing with the baby. The stress hormone cortisol is the OPPOSITE of oxytocin and cortisol levels go down just from holding hands. We feel the "love hormone" towards all our subscribers because YOU'RE the reason this wonderful website is HERE! Without you, we'd have to go away, just like a spurned lover and only YOU can fix that: Subscribe today!