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Mammals dream about the world they are about to experience before they are born

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Re: Mammals dream about the world they are about to experience before they are born

#161

Post by slickrick216 »

l33t2328 wrote: post #160
jacinda wrote: post #70

Earlier quoted context omitted.

> this is commonly attributed to the fact that human babies have immature brains that cannot mature due to birth canal constraints, which is constrained by pelvis size which is constrained by the need to walk upright Interestingly, the EGG hypothesis postulates that the constraining factor is not pelvis size, but rather that neonates consume so much energy that we give birth just before a women's metabolic limits wou…

> consume so much energy that we give birth just before a women's metabolic limits would otherwise be overrun Since babies traditionally breast feed and thus survive solely on the mother’s energy after birth, this explanation doesn’t seem to hold water.

Breast feeding is quite hard on women and many women struggle to sustain the child on the breast alone. There’s a history of communal feeding which adds new energy into the equation and also mixed feeding once the child is old enough. I would say it’s probably a continuation at the peak metabolic rate described in the parent post.

Re: Mammals dream about the world they are about to experience before they are born

#162

Post by minitoar »

l33t2328 wrote: post #160
jacinda wrote: post #70

Earlier quoted context omitted.

> this is commonly attributed to the fact that human babies have immature brains that cannot mature due to birth canal constraints, which is constrained by pelvis size which is constrained by the need to walk upright Interestingly, the EGG hypothesis postulates that the constraining factor is not pelvis size, but rather that neonates consume so much energy that we give birth just before a women's metabolic limits wou…

> consume so much energy that we give birth just before a women's metabolic limits would otherwise be overrun Since babies traditionally breast feed and thus survive solely on the mother’s energy after birth, this explanation doesn’t seem to hold water.

The truncated gestation is sort of taking that into account, at least according to this paper https://www.pnas.org/content/109/38/15212

Re: Mammals dream about the world they are about to experience before they are born

#163

Post by jacobolus »

davchana wrote: post #158
jacobolus wrote: post #98

Earlier quoted context omitted.

The balance can also be trained relatively quickly, but newborns typically get very little practice. If you start occasionally holding your baby up by the thighs when they are 4–5 months old (their back/abdomen muscles at that point are typically plenty strong), after about a month they will have the balance to hold their torso upright when sitting on an adult’s shoulders, for at least a while. By age 8–9 months they…

> If you start occasionally holding your baby up by the thighs when they are 4–5 months... Do you mean baby sits on my shoulder with his legs around my neck, I am holding on to his thighs, and he can hold on to my head with arms? We both face forward in same direction.

No, I mean you hold your baby by the thighs, facing you, and let him balance his torso upright by flexing his abdominal/back muscles. At first, the baby will not have the coordination to stay upright very well, but actively stabilizing himself will train that balance. Because you are holding the thighs, the baby only has to stabilize one joint (the waist).

Then after a month or two of practice (a few minutes per day, nothing too serious here) you put your baby on your shoulders, holding his ankles, and he will be able to hold his torso up with his abdominal muscles for at least a few minutes at a time. Practice this for a few more weeks and you will be able to walk around town with the baby on your shoulders.

Re: Mammals dream about the world they are about to experience before they are born

#164

Post by jacobolus »

mortehu wrote: post #132
jacobolus wrote: post #98

Earlier quoted context omitted.

The balance can also be trained relatively quickly, but newborns typically get very little practice. If you start occasionally holding your baby up by the thighs when they are 4–5 months old (their back/abdomen muscles at that point are typically plenty strong), after about a month they will have the balance to hold their torso upright when sitting on an adult’s shoulders, for at least a while. By age 8–9 months they…

Based on my experience with our first child, these might be placebo exercises, and the babies might have met those goals on their own. Assuming you haven't done a randomized trial.

Based on which experience? My experience with now 2 young kids and their playground buddies is that whichever skills they regularly practice improve very dramatically compared to skills they don’t practice. The differences are not at all subtle.

If you get a few 3-year-olds and e.g. get one to practice kicking a ball for 10 minutes per day, another to practice riding a 2-wheeled scooter, another to practice hanging from monkey bars, and another to practice swimming, after a few months there will be a wide gulf between their abilities at those skills.

Re: Mammals dream about the world they are about to experience before they are born

#165

Post by TheGeminon »

eru wrote: post #142
mandelken wrote: post #131

Earlier quoted context omitted.

Perhaps it’s more than just calories or energy intake, but as well doing the breathing, immuno responses, digesting, filtering blood etc. for both mother and baby?

Maybe. But now we are just speculating.

> Instead, the mother delivers and the neonate’s growth rate slows relative to its fetal growth rate, keeping both the offspring’s and the mother’s energy requirements in check.

Growth rate slows after birth, so that would account for some of that. Mother’s also would not need to carry around the weight of the baby, and would be more able to provide for the child.

Re: Mammals dream about the world they are about to experience before they are born

#166

Post by Naracion »

FartyMcFarter wrote: post #118
agent008t wrote: post #111

Earlier quoted context omitted.

Putting on 6kg in a year is not that fast, people do sometimes gain weight faster than that in adulthood.

That's not growth, just fat accumulation which is a much simpler process.

How are you defining growth? Are you defining it by volume? Ie assuming the body mass density remains the same, how much does the weight increase (which means the body is volumetrically growing)?

If not--I am very lightweight right now, and I'm trying to put on body mass by eating more and exercising. While my volume will increase, my main growth is in density. My growth is not in fat, but actual muscle mass. Is this growth? If so, I have gone from 125lb to 140lb in ~2 months, which in absolute terms is obviously more than the baby (my goal is 160lb by the end of the year).

A few years ago, I went from ~130lb to 165 lb in three months--blame the free food at FAANG cafes during an internship. But this might be closer to what you were saying earlier--putting on fat.

Edit. I guess in the original statement saying that a person will never gain weight at this rate again there should be the explicit assumption that we're talking about natural growth, not growth due to external factors (ie more eating--intentional or not). In that case, that statement would be true.

Re: Mammals dream about the world they are about to experience before they are born

#167

Post by lostmsu »

echelon wrote: post #20
gonehome wrote: post #13

Earlier quoted context omitted.

I don't think brains are pre-wired to recognize 3D objects. There was an example case of a blind man with cataracts getting it fixed at around 50 years old. People were curious if he would be able to know if a sphere was round just by looking at it without touching it. IIRC - not only could he not do that, but he couldn't visually interpret shadows (saw them as black splotches - didn't recognize depth), and was confu…

Fascinating anecdote, and I'd love to see the report on this. I wonder what else they learned from such an interesting case study. But I doubt it's 100% "no pre-wiring". What about gravity and musculature? Surely brains must know or train on these in some way before birth. And what about fight or flight reflexes and presupposing monsters in the shadows? My understanding is that these had a primitive evolutionary basi…

What about musculature? Human babies mostly just violently shake all hands and legs right after birth.

Re: Mammals dream about the world they are about to experience before they are born

#168

Post by davchana »

jacobolus wrote: post #163
davchana wrote: post #158

Earlier quoted context omitted.

> If you start occasionally holding your baby up by the thighs when they are 4–5 months... Do you mean baby sits on my shoulder with his legs around my neck, I am holding on to his thighs, and he can hold on to my head with arms? We both face forward in same direction.

No, I mean you hold your baby by the thighs, facing you, and let him balance his torso upright by flexing his abdominal/back muscles. At first, the baby will not have the coordination to stay upright very well, but actively stabilizing himself will train that balance. Because you are holding the thighs, the baby only has to stabilize one joint (the waist). Then after a month or two of practice (a few minutes per day,…

Oh I get that. Kind of what my parents did that always pick up baby from waist(if he is sitting down) & holding him only at thighs/waist. I see some people pick up by from their underarms.

Re: Mammals dream about the world they are about to experience before they are born

#169

Post by agent008t »

Naracion wrote: post #166
FartyMcFarter wrote: post #118

Earlier quoted context omitted.

That's not growth, just fat accumulation which is a much simpler process.

How are you defining growth? Are you defining it by volume? Ie assuming the body mass density remains the same, how much does the weight increase (which means the body is volumetrically growing)? If not--I am very lightweight right now, and I'm trying to put on body mass by eating more and exercising. While my volume will increase, my main growth is in density. My growth is not in fat, but actual muscle mass. Is this…

I wouldn't say that growth through eating is unnatural though.

Re: Mammals dream about the world they are about to experience before they are born

#170

Post by Naracion »

agent008t wrote: post #169
Naracion wrote: post #166

Earlier quoted context omitted.

How are you defining growth? Are you defining it by volume? Ie assuming the body mass density remains the same, how much does the weight increase (which means the body is volumetrically growing)? If not--I am very lightweight right now, and I'm trying to put on body mass by eating more and exercising. While my volume will increase, my main growth is in density. My growth is not in fat, but actual muscle mass. Is this…

I wouldn't say that growth through eating is unnatural though.

I guess what I might have implied by "natural" is growth from growing older as opposed to growth from nutrition.

But in that sense, of course a baby will have more growth than an adult--isn't it reverse exponential?

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