[ardit33]

Alas, the ability to smile is something that is innate, and some babies do smile right after birth. (rare, but it happens), but it is not necessary tied to emotional content.

"Neonatal smiling occurs from birth to one month of age and shows no emotional content. Smiles are spontaneous and often occur while the baby is drowsy or during REM stages of sleep. Baby smiles are subcortical in origin and will actually decrease with maturity (so premature babies smile more than full-term babies)."

Also there is proof that babies seems to be able to smile even though they are uborn/ still in the womb, which means the ability to smile is a universal human trait that is culture independent.

http://www.dailymail.co.uk/health/article-196020/Babies-smil...

[skywhopper]

The ability to smile is not necessarily connected to the meaning of a smile, though. The article seems to assume a connection between smiling and happiness that isn't necessarily supported. (A good explanation of such a connection would need to contrast it to other aspects of communication which we don't question the cultural basis for.)

[seanmcdirmid]

> The ability to smile is not necessarily connected to the meaning of a smile, though.

Pediatricians call it a "social smile", and it is an important milestone in newborn development. See https://www.webmd.com/parenting/baby/babys-first-social-smil....

Evolutionary, I think the intention is to bring parents further under the baby's spell, since otherwise they might give up because taking care of a baby is a lot of work!

[myth_drannon]

More than parents which are attached to the child with hormones, the smile is for the strangers so they do not harm them. At some stage babies smile all the time to strangers. That's before they get older and understand the concept of parents vs strangers.

[dingaling]

Cross-species, the opposite of 'smile at strangers' that I had to learn was when handling distressed dogs.

To a human a smile is cute, to a dog it is baring of teeth in a challenge.

[stevekemp]

Our baby is a fascinating example of this - every time he sees a stranger he makes a big smile.

He seems to just love people, and because of his big eyes and big smile it is rare that I can take him shopping, or for a walk, without at least one stranger talking to me about how happy he looks.

[seanmcdirmid]

Ya, same here, though it seems to be tapering off after 1.

[sitkack]

I got smiled at by a 9 month old on the plane just yesterday, the subtext was, "please don't eat me or my family."

[bonesss]

... don't leave us hanging, what did you do?

Did you let the infant assert dominance, or did his parents learn a lesson about the social hierarchy?

[ardit33]

What you saying is one side of speculation/explanation. The article particularly mentions that when babies are in the womb, they feel content and that's what the smiling is, but we don't know if it is for sure. (i.e. it can be just a reflex, or actual display of being "content").

Smiling, however, cannot be interpreted as preparation for birth but may be a reflex, Prof Campbell said.

He added: "What's behind the smile, of course, I can't say, but the corners turn up and the cheeks bulge ... I think it must be some indication of contentment in a stress-free environment."

in any way, so socialization is a big part of it. We know most humans are born with the ability of speech, but if they are not taught/socialized at early age, then they will never be able to speak later (apart from uttering primitive sounds), but they still can utter sounds.

It could be the same with smiling. All humans are born with the ability of a 'primitive smile' which can be further developed and refined socially, but ability is innate.

The studies that mention that all smiling is socialized is yet another wave of bunk science that tries to attribute "socializing" and indoctrination to every human behavior, where there are clear indication that it is not true.

http://www.doctortipster.com/6920-smiling-is-an-inherited-be...

[m_mueller]

Ours did it right after birth - I know one shouldn‘t prescribe meaning to it but it‘s really quite something seeing it. I got photos but I guess I shouldn‘t upload publicly.

[taneq]

Babies 'smiling' can also indicate gas.

[ars]

That is an old wives tale. It's not actually true. But people love repeating it because it sounds funny.

[jjeaff]

For some babies it's definitely true. Ours makes a very cute open mouth smile when she is trying to push gas (or poop) out. You don't need a scientific study to tell you that a big smile while grunting, followed by a big fart or dirty diaper several times a day makes the smile a sign.

[taneq]

Interesting, I'll have to look into this. A quick search was inconclusive but showed a split between "sciency" sources (saying no relation between infant smiles and gas) and "parenty" sources saying it's gas. Thanks!

[hexane360]

That actually sounds pretty conclusive to me.

[taneq]

I meant 'inconclusive' as in "in 2 minutes of searching I found a couple of papers whose abstracts said no causation between gas and smiling, and about four of five 'mummy-type' sites that asserted the correlation." To me that points to 'no causation' being the likely case but I'm not going to just declare it as proven on the basis of the first two papers I turned up.