> the other allows them to mostly passively receive milk delivered via gravity.

That's not how bottles work. You have to actively suck onto the nipple in order to get milk, and you can only get a small quantity per suck. Sure, you can get it in edgewise and bite down so it opens up and the milk runs, but that's not how babies drink.

Source: I used to drink from a bottle well into my teens, because I found it a convenient delivery device for chocolate milk in bed.

I find this the most credible source in the thread.

The way that sucking from a bottle vs. teat works is dramatically different.

A quick web search turns up many images and explanations, e.g. http://www.brianpalmerdds.com/pdf/adsm_section_c.pdf

I was joking.

When you feed a baby, you tend to unscrew the bottle to remove the vacuum effect and make it easier. Some of them are even marked to indicate the intensity of the flow.

Source: experience feeding and buying baby's bottles.

edit: As a teen, you probably didn't have the same incentives, you didn't have other things to take care of in parallel, your jaw was more developed, and a tightly screwed bottle will hardly drop anything if you don't shake it, so you could lay down in any position you wished, and take as long as you wanted.

It's not about the vacuum effect in the bottle, it's about how the nipple is constructed. When you suck on the end, the "neck" closes because of the pressure and won't let more milk flow. I'm a bit hazy on the mechanics because it's been a while, but I'm very sure of the end result.

I imagine you can easily try it and report back if you have quick access to a bottle, maybe you can shed more light on this.

Babies don't suction milk out of the breast, rather they take the nipple and areola into the mouth and squeeze it between the tongue and palate to express milk.

Milk from bottles is by auction and it's usually easier than breastfeeding.

(Learned this from a lactation consultant for my daughter)

Having read more about the mechanism of suckling, it seems even more clearly important to the development of the jaw, because the baby uses their tongue to draw the milk out of the nipple, which requires applying pressure with the tongue from front to back against the palate. Bottle feeding requires simple general suction.

Agree you're correct. My broader point is that the actions are quite different and express different forces on the jaw, triggering different growth.

I'm not a female, but don't mothers squeeze their breast while the baby is suckling to push milk through? How much force does that generate?

No, that's not necessary. You can even nurse while fast asleep if the baby has a good latch.

And yes, there are babies that perform self-service. It's a good way not to have a sleep deprived mother.

I should have known this, but I'm glad I know now before assuming in real life. Thanks!

Thats usually not needed. Towards the end of the breastfeeding session when the baby has drained much of the milk, mothers will often massage the breast to push more milk towards the end. That can make milk squirt out, but it isn't the purpose. Really full breasts can definitely leak milk without any suckling, but most of the milk comes out as a result of the baby suckling.

This reminded me of Miike's "Visitor Q".