[g82918]

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.