Not that I have studied this particular behavior, but evolutionary type theories like this one, tend to be found wanting after later research. For a more common example, look at the paleo diet. At a glance, the theory seems a bit bonkers if you consider natural feelings around kissing you may have had around puberty. I would imagine there might be a better explanation than some nuturing/feeding urge.

Edit: Not to be that dude, but for the downvote, explaining better how/why this feeding explanation makes sense would be nice. I thought my comment advanced the conversation somewhat.

Ok, people enjoy it because it makes them feel intimate with each other,the act of intimacy arouses sexual desire. Is that enough or is the studying ancient cultures part mandatory?

The oversimplified brand of logic is just you generalizig my disagreement to support your brand of over analysis.

Please, take as much closer look as you want but do look at the whole picture,not just the booky part. Ask yourself why you enjoy it first,ask why others enjoy it and start there and stop when you have enough to adequately explain it.

I stand by my statement, a psychological need for intimacy is the root of the desire. It could be licking each others ear lobes or something that would now sound weird, the act is merely an expression of intimacy which is to know and to be known.

I would even say your conclusion can be viewed as an "oversimplified brand of logic" as you put it since you are not explaining why feeding chewed food is tied to sexual expression of affection and why it is prevalent strictly in a sexual relationship and why parents don't make out with children or between close friends and siblings,when adopted why did it become sexual? And to be clear a peck on the surface is not what we are talking about here since that is not exclusive to lips (forehead,etc...)

>Is that enough or is the studying ancient cultures part mandatory?

The evolutionary biology approach provides pretty deep insight into human behaviour. Making out is a dissociative state where each person uses their highly developed talking muscles to physically interact with each other. No other body part even makes physical sense. Your ear lobe isn't dexterous - that would be one way interaction.

>Please, take as much closer look as you want but do look at the whole picture,not just the booky part. Ask yourself why you enjoy it first,ask why others enjoy it and start there and stop when you have enough to adequately explain it.

How is your inward facing perspective as "the whole picture"? Evolutionary biology is the whole picture.

> Evolutionary biology is the whole picture.

And how dare I question it or anything outside of it right? Sounds very smart and sciency,I will leave you to it then.

Oh,and I meant introspection, actually asking people, psychological examination of the subject are part of the evidence picture before you come to a conclusion. Apparently,anything short of an explanation involving an "evolutionary" need to exchange chewed food (even though many cultures don't do intimate kissing -- I suppose your claim is those humans evolved differently and have adopted it in the last century against their evolutionary need?) is offensive to your line of thinking.

I suggested other reasons than exchanged foods - it is because the dexterity is already present in those muscles due to talking and chewing in my opinion. I don't think the dexterity of your mouth muscles have evolved significantly in the last century. It is an ability that is a indirect benefit from other evolved traits.

Insight obtained from introspection or evolution in the 100 year scale will be mostly psychological/cultural. If you want to understand the big picture including physical justification you need to look at the large time scale perspective because it takes much longer for those changes, psychological and cultural justifications are dependant on the physical. Maybe that's too "booky or sciency" of a perspective, but I don't think so.