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Why Do Humans Grow Up So Slowly? Blame the Brain

Unknown Lamer posted about 4 months ago | from the brains-considered-harmful dept.

Science 128

sciencehabit (1205606) writes Humans are late bloomers when compared with other primates — they spend almost twice as long in childhood and adolescence as chimps, gibbons, or macaques do. But why? One widely accepted but hard-to-test theory is that children's brains consume so much energy that they divert glucose from the rest of the body, slowing growth. Now, a clever study of glucose uptake and body growth in children confirms this 'expensive tissue' hypothesis.

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Too much wanking (0)

Anonymous Coward | about 4 months ago | (#47753519)

Losing your precious bodily fluids. Purity of essence man. Dabney Eats it

Re:Too much wanking (-1)

Anonymous Coward | about 4 months ago | (#47753833)

I am forty years old and I just want to say this: beaner, chink, cracker, dune coon, gook, greaseball, honky, faggot, froggy, jap, kike, kraut, limey, mick, nigger, nip, paddy, polack, redneck, russky, slut, spic, wetback, whiteboy, whore.

Thank you.

Re:Too much wanking (0)

davester666 (731373) | about 4 months ago | (#47754093)

Why do you feel you have to list your sexual conquests here?

Sperm to frogs (4, Funny)

tepples (727027) | about 4 months ago | (#47754067)

You have to clean out the pipes every once in a while before the sperm, well, mature [wanderings.net] .

Re:Sperm to frogs (-1, Flamebait)

sillybilly (668960) | about 4 months ago | (#47754539)

Hahaha, that's a funny pic. There is this thing called wet-dreams you get if you haven't done it in, oh, say every 4 months, maybe every 2 months if you're near the peak of 16-21 years. I wonder how long the astronauts stuck in a claustrophobic space station can hold out without a wet dream. Or maybe they do get off? Pooping in weightlessness must suck too. We don't usually see youtube videos of astronauts pooping and the shit floating around in the cabin.
So anyway, back to the original topic. One of the reasons for the very short life cycle of most mammals is reproductive competition, as those that do it at a faster rate quickly displace the slow breeders. For instance in the US it's common to have black teenage mothers at age 13 from generation to generation, and 39 year old grandmothers. Welfare takes care of all the kids, and under such circumstances the black population quickly drowns out a slow breeding white one that goes to college first, gets a carrier, dates around with 3 guys for 2 years each, gets married by age 33, and maybe pops the first baby by age 39, where a white couple barely maintains population while the black couple, as grandmothers, have like 5 kids each with 2 grandchildren already. Fast breeding comes about in low environmental stress environments where life is good, and easy, the weather is always warm so you don't need clothes, there is usually little war, and for food you take a stroll in the nearby jungle and pick it off the lush vegetation. Life is also easy where welfare pays for the kids. However, under high stress environments, like lots of warfare, lots of cold, and lots of planning required, you get childish extremely slow maturing males that have a loooong time to play video games and the like, and not take girls or life seriously, but with all that playing and training, comes good training, and you get these ultra-age-separated couples, where the men are really old and immature, a whole decade older than their female partners who mature very young, and keep the reproductive cycle still fast enough - as it is the female that is the holdup, she takes a whole 9 month per baby, the male can inseminate hundreds of females in the time a female produces a single offspring. Also these women become extremely perverted because they have to lower their standards to where they are willing to consider an old, unattractive, wrinkly piece of blubber fat with hair on the back as sexually hot, and they are so high sprung on hormones, when they meat up a male from a fast breeder population that's young, and selected for by females on sexual appearance like dick size or athletic body not on strategic military skill and the like, they cannot control themselves. It's just the way it is. The long life cycle of humans, and especially the long breeding cycle of going from female mother to female mother presently hitting puberty near age 12 or 13, might be disappearing as the fast breeders able to hit puberty at age 10 or 8 will take over the population, as long as life is easy, there is no starvation, and the welfare check in the mail is guaranteed.

Re:Sperm to frogs (5, Interesting)

sillybilly (668960) | about 4 months ago | (#47754575)

Lifespan among other mammals is usually short because the required training to make it is not that complicated, unlike in a complex human or even great ape society. By the way the life expectancy of most cavemen was less than 40 years, and compared to horses and elephants, it's not that long. Only in recent times through agricultural and technological advances and good life has life expectancy increased. So this ultra life expectancy of 80 years may not be long because the brain requires it or demands it, but more like the brain allows it, so why not? Having great-grandmothers, grandmothers mothers and daughters together in a village, usually makes for a more successful village where members proliferate marrying into other villages taking their customs of sticking together through the long generations, and having long generations, compared to short lifespan mother-child only structures usually found in the wild, where the grandmother and great grandmother don't participate, and don't make a difference whether they still exist or not.

Re:Sperm to frogs (1)

schlachter (862210) | about 4 months ago | (#47757427)

since some trees and such can live for hundreds of years, and turtles can live for more than 100 yrs, I wonder if we can learn from them how to extend life.

Re:Sperm to frogs (1)

ruir (2709173) | about 4 months ago | (#47754741)

I bet diapers are standard gear in space. You cannot shit properly without gravity.

Re:Sperm to frogs (3, Insightful)

Anonymous Coward | about 4 months ago | (#47754819)

I bet diapers are standard gear in space. You cannot shit properly without gravity.

Thank God you both have imagination and speculation to help fill in your gaps in knowledge.

If only someone could invent a vast, searchable information databank that was computer accessible via network where you could answer these inquiries then perhaps you might not be forced to speculate as much. I would call such a thing a CompuNet.

Oh well, we can dream can't we?

Re:Sperm to frogs (1)

sillybilly (668960) | about 4 months ago | (#47757957)

I was thinking of a light suction vacuum cleaner device with a centrifuge separator, that has soft foam to conform to the shape near your anus. The light suction would come about from a Y or F connection, where some of the air is taken from the room at very high speed, and that opening has an adjustable flap, and you still get enough speed and velocity to centrifuge separate the liquids and solids, regular wet-vac style. Maybe something insertable, but now we're stepping into gay territory that some people might have objections to. But women have both tampons and pads, and preferences vary, so something conforming to the shape of your anus on the outside, or something you can insert, you could pick and choose, by changing the adapter tip. Options are always a great thing.. Btw, diapers are messy too, then you have to wipe your ass cheeks from the poop that spreads outwards all over them, they are not such a godsend either. That's why a rotating cylinder space station is like an absolute must, and for that it has to be huge size so you don't get dizzy from the difference in blood pressure between your toes and head, but at least you could take a nice comfortable shit near the rim, the outer cylinder wall, even if you wander in the the weighlessness or lower weight central floors and areas.

Re:Sperm to frogs (0)

Anonymous Coward | about 4 months ago | (#47756029)

... wow, it's like Charles Darwin and Time Cube had a baby in here

Too much "blame". (1)

Anonymous Coward | about 4 months ago | (#47754209)

Why "blame", growing slowly means we also live longer, and the brain has given us enormous advantages. I rather praise, not blame.

Macaque (0)

Anonymous Coward | about 4 months ago | (#47753533)

Best selfie a macaque ever took! http://blogs.wsj.com/law/2014/... [wsj.com]

Re:Macaque (0)

Anonymous Coward | about 4 months ago | (#47756397)

Yeah whateva, suck macaque

not so fast (5, Insightful)

arth1 (260657) | about 4 months ago | (#47753549)

That there is an inverse correlation between brain glucose use and body growth does not imply that the brain's use of glucose stymies the growth until later.
If that were the case, kids who are overfed carbohydrates would be smarter and taller, not fatter and dumber.

My guess is that slow growth is selected for because children who look like children enjoy special care and protection by adults. Growing to adult size by age 7 might be detrimental to survival.

Re:not so fast (1)

Anonymous Coward | about 4 months ago | (#47753595)

What utter fucking rubbish. Getting to the point you can run / fight according to Darwin and thence eventually able to breed is more beneficial. Being a walking target for disease and predators is from a Darwin perspective really bad, growing up fast is what should have been selected.

Re:not so fast (4, Interesting)

Beck_Neard (3612467) | about 4 months ago | (#47753639)

Yup, and what makes it even more rubbish is the idea that simply feeding someone more food is enough to change their biochemistry, metabolism, and energy distribution budget towards diverting more energy towards growth and less towards the brain, and that blood glucose levels are determined by dietary carbohydrates.

But I do enjoy reading the pseudo-intellectual armchair philosophizing that we see so often.

Re:not so fast (4, Interesting)

Anonymous Coward | about 4 months ago | (#47753797)

Nobody should be allowed to comment on genetics or evolution until they've read The Selfish Gene. While some small parts of it are arguably out-dated, it really helps orient one's mindset regarding evolutionary genetics. The Selfish Gene will survive as an extant and useful work much longer than Darwin's On the Origin of Species.

Even many biologists should read it. Too many biologists lack rigor when they hypothesize about evolutionary behavior. The Selfish Gene really lays out not only what has been effectively proven about evolutionary genetics, but provides examples of the complex but elegant mechanisms that _new_ evolutionary processes (e.g. group selection) will probably also look like if they can ever be proven.

Re:not so fast (2, Informative)

Half-pint HAL (718102) | about 4 months ago | (#47754113)

No-one should be allowed to comment on anything if they have read The Selfish Gene. Dawkins is a dangerous hack and a terrible writer. His pop-science books never educate the state-of-the-art, but instead indocrtrinate his view to the exclusion of all others.

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47754135)

Groups selection needs to be proven? I thought it was fairly obvious, without a need to read [suggested reading material] or even be a biologist.

Re:not so fast (1)

Beck_Neard (3612467) | about 4 months ago | (#47754753)

Group selection is pretty controversial; we know that the initial group selection ideas were not true.

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47757227)

Group selection is pretty much out the window

Re:not so fast (5, Insightful)

ShanghaiBill (739463) | about 4 months ago | (#47753821)

growing up fast is what should have been selected.

Not necessarily. The major threat to children in primitive hunter gatherer societies is not predators but hunger. By staying smaller during their formative years, they reduce the amount of calories need to survive. But the selection pressures are different on boys and girls. Girls are generally able to procreate as soon as they reach puberty. But boys need to wait till they are older, and have built up social status. So it makes sense for girls to mature faster, and that is what happens. Look at a group of kids in 4th or 5th grade, and the girls are several inches taller than the boys.

Re:not so fast (5, Interesting)

Jane Q. Public (1010737) | about 4 months ago | (#47754043)

Not necessarily. The major threat to children in primitive hunter gatherer societies is not predators but hunger. By staying smaller during their formative years, they reduce the amount of calories need to survive.

This. Also, it takes time to learn the vast amount of information that it takes for a human being to really be smart enough to manipulate its environment... which evolution has obviously selected for. Chimps, for example, often actually outpace human learning for up to 2 years, but then humans continue to learn while the chimp rapidly levels off. Keeping resource use to a low level during this long learning phase is likely a long-term survival trait.

Also it should be noted that another factor in humans' slow growth is already known: humans can only have babies with brains so big, before birth becomes a very big problem. So a longer period is needed for the human brain to grow to its adult size.

But the selection pressures are different on boys and girls. Girls are generally able to procreate as soon as they reach puberty. But boys need to wait till they are older, and have built up social status. So it makes sense for girls to mature faster, and that is what happens. Look at a group of kids in 4th or 5th grade, and the girls are several inches taller than the boys.

It is more accurate to say that boys and girls mature at different rates.

If you adjust for the probable influence of estrogen mimics in our current environment, human females start to mature sexually before males do, but actually finish their sexual maturation later. You are referring more to social factors than genetic: often males need to be older to establish themselves in order to semi-permanently mate, but that is not the same things as physical sexual maturity needed to procreate.

Re:not so fast (3, Interesting)

ShanghaiBill (739463) | about 4 months ago | (#47754211)

You are referring more to social factors than genetic

These are not separate factors. Genes influence social behavior, and social behavior influences which genes are selected. In ALL human societies, men prefer women younger than themselves that are physically attractive, which correlates with fertility. In ALL human societies, women prefer men with high social status, and greater resources. It is unlikely that such universally pervasive preferences are purely "social" rather than genetically innate. Chimpanzee males have no preference for younger females, and when given a choice of mates, will prefer older females. Female chimps do not have the same decline in fertility with age that women have, and more mature and experienced females have a greater chance of successfully rearing offspring.

Re:not so fast (1)

Jane Q. Public (1010737) | about 4 months ago | (#47754369)

In ALL human societies, men prefer women younger than themselves that are physically attractive, which correlates with fertility. In ALL human societies, women prefer men with high social status, and greater resources.

As a generalization, this is true enough. So, I will amend my comment. They might be genetic factors, but they aren't overt physical factors. The fact that males tend to be older when they mate is not a matter of sexual maturity, which generally comes long before then.

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47757443)

In ALL human societies

[citation needed]

Re:not so fast (2)

RubberDogBone (851604) | about 4 months ago | (#47755303)

It takes a long time to teach our kids because the system we have for teaching them is horribly inefficient and has been for thousands of years at this point.

But it carries on not because it's good but instead because it is so indoctrinated and there is no allowance to try anything radically different. If you try even things like "new math" parents freak out because that's not what they learned.

In fact, the entire schooling process we have, from primary schools to colleges and post-graduate should be reexamined at every level. Does it make sense to do it this way, or are we doing it this way, effectively spending a third of someone's life on school, only because the system is dedicated to this method?

Basically, the concepts of college as we know them are at least several hundred years old. Virtually every area of science and medicine and life itself has changed over that time, however we still teach basically the same way. This doesn't make any sense. That process should have changed and evolved like all the others but it largely hasn't. This should be questioned by anyone -are we doing this the right way? Does it make sense? Or is there a better way?

However everybody currently on the loose was educated that way so they have no incentive to change it for new kids, and of course the educators themselves have little or no incentive to reinvent how they do what they do, and even the parents have no incentive to let their child try a new way that may jeopardize the child's accomplishments compared to other kids -nobody wants their kid to be the first one to never actually have a diploma for something, for example.

Spending a third of someone's life on schooling years is on the face of it ridiculous. But I don't think this can possibly change. And that's too bad.

procreation over the years (1)

schlachter (862210) | about 4 months ago | (#47757569)

It's interesting how for most of human history people were partnering up and and having babies around 14/15 yrs old and being grandparents at 30 yrs old and great grandparents at 45 yrs for the few that were lucky enough to live that long.

Now in our highly specialized society, people are commonly having babies in the mid-30s.

Re:not so fast (1)

Anonymous Coward | about 4 months ago | (#47754123)

My son is 5. In dog years he would be running/fighting/making Darwin happy by now. In reality he is very clumsy and unprepared to run/fight. If he were adult-sized by now it would be a major disaster, which would make Darwin very unhappy. On the plus side his intelligence surpassed the smartest of dogs by now, making Darwin very happy. Cut the BS and learn to apply Darwin correctly.

Re:not so fast (1)

indeterminator (1829904) | about 4 months ago | (#47754467)

Try behaving like a seven-year-old in grown man's body (on the webs doesn't count), see how that works for you. Your older peers will be a bigger threat to you (and you to them) than disesase and predators.

Re:not so fast (0, Redundant)

Anonymous Coward | about 4 months ago | (#47753603)

For crying out loud, how many times do I have to say it? CORRELATION DOES NOT IMPLY CAUSATION!

Correlation does not imply causation!

Correlation does not imply causation!

CORRELATION DOES NOT IMPLY CAUSATION!

Correlation does not imply causation!

Correlation does not imply causation!

CORRELATION DOES NOT IMPLY CAUSATION!

Correlation does not imply causation!

CORRELATION DOES NOT IMPLY CAUSATION!

CORRELATION DOES NOT IMPLY CAUSATION!

Correlation does not imply causation!

Correlation does not imply causation!

Correlation does not imply causation!

CORRELATION DOES NOT IMPLY CAUSATION!

Correlation does not imply causation!

CORRELATION DOES NOT IMPLY CAUSATION!

Correlation does not imply causation!

Correlation does not imply causation!

CORRELATION DOES NOT IMPLY CAUSATION!

Correlation does not imply causation!

Why don't you get it? CORRELATION DOES NOT IMPLY CAUSATION!

Just because there is a correlation it DOES NOT mean that there is causation! This is not difficult to understand, so why are you having so much trouble comprehending it?

Re:not so fast (4, Funny)

Xiver (13712) | about 4 months ago | (#47753731)

You can scream this at the top of your lungs until you are blue in the face, but it probably won't make a difference. Explaining it carefully might convince a few people, but not about things they already believe in. Its been said so much that you wouldn't even post it under your username, because you know it will get adversely moderated. People have read it so much they cringe when they see it.

You'll never be able to convince people that toasters don't cause suicidal tendencies in teenagers.

Re:not so fast (3, Interesting)

jandersen (462034) | about 4 months ago | (#47754893)

You'll never be able to convince people that toasters don't cause suicidal tendencies in teenagers.

Depends on the toaster, wouldn't you agree? I have had toasters that made me want to kill whoever sold it to me.

I think, if we take away the hype and the misunderstandins on the part of the article, that what we have here is an interesting observation that does support the theory that brain-growth may be one of the factors determining when we become adults. I don't think it is true, though; it seems to me that the biggest evolutionary advantage we have is, in fact, the prolonged period of brain development and plasticity and the evolution of the family unit that supports a long childhood; this, incidentally, includes the fact that we, as the only species I know of, also live long after reproduction. Having grand-parents who can pass their experience on to the youngest, seems like a huge advantage to me.

Re:not so fast (2)

PPH (736903) | about 4 months ago | (#47757053)

You can scream this at the top of your lungs until you are blue in the face,

Not necessarily.

You haven't proved a causative link between excessive vocalization and having a blue face.

Then how do we ever get to causation? (1)

Anonymous Coward | about 4 months ago | (#47753751)

If correlation does not imply causation, how do we ever determine causation?

Hitting you upside your thick skull with a 2x4 is not an implied cause of the concussion you have the next day?

How do we determine what people are allergic to?

How do we determine physical laws? What are experiments other than attempts to find correlations that we can codify into physical laws?

Where did Newton's Laws of Motion come from? Maxwell's Laws?

To wit: how does the observed gravitational force (measured by whatever means) CORRELATE with the distance between two object?

From that CORRELATION we infer that the force of gravity which CAUSES the object to move together follows an inverse square law.

Look at the CORRELATIONS revealed by variations of the double-slit experiment [wikipedia.org] . And the CAUSES that are inferred from those CORRELATIONS.

Re:Then how do we ever get to causation? (1)

Anonymous Coward | about 4 months ago | (#47753809)

His comment already answers all of your questions, before you even asked them. Maybe you didn't understand the gist of his message? Here, let me quote it for you:

CORRELATION DOES NOT IMPLY CAUSATION!

Re:Then how do we ever get to causation? (1)

tepples (727027) | about 4 months ago | (#47754003)

Then what not-correlation thing does imply causation?

Re:Then how do we ever get to causation? (0)

Anonymous Coward | about 4 months ago | (#47754213)

Isn't this one obligatory in this situation? :) http://xkcd.com/552/

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47753829)

Correlation does not imply causation!

What do you mean?

Re:not so fast (2, Funny)

AK Marc (707885) | about 4 months ago | (#47754089)

Every time I shoot you in the brain, you die. But correlation does not imply causation, so it must be some other reason.

Re:not so fast (3, Insightful)

Zuriel (1760072) | about 4 months ago | (#47754373)

'Imply' means something different in formal logic. You can use this line instead: "Just because two things happen at almost the same time doesn't prove that the first one caused the second."

The guy who got shot in the brain could have had a heart attack seconds earlier. You still need to do the autopsy to prove that the shot was the cause of death. Yeah, it probably was, but 'probably' isn't proof.

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47754481)

'Imply' means something different in formal logic.

we're talking about the real world, so the formal-logic definition of imply doesn't apply. It only makes sense in math. Imply in real-world terms means hint at.

You can use this line instead: "Just because two things happen at almost the same time doesn't prove that the first one caused the second."

That's a different statement. If A doesn't cause B but there is a C that causes both, this is a causation.
  Of course our measurements for A and B could still be correlated without any causal relation that connects them, but that's improbable.

Re:not so fast (1)

Anonymous Coward | about 4 months ago | (#47754489)

Also, 'happen at the same time' is something very different from 'are correlated'.

Re:not so fast (1)

arth1 (260657) | about 4 months ago | (#47755677)

Imply in real-world terms means hint at.

No, it doesn't. You have the wrong idea of what "imply" means. It is not a synonym for "hint at" or "suggest" any more than "implication" is a synonym for "hint" or "suggestion". It is a near synonym to "mean".

That you have two X chromosomes and no Y chromosome implies that you are female. It does not merely hint at it.

When I used the word imply in the real world example of my GPP, it was to say exactly what I said. Not your uneducated guess at what it means.

Re:not so fast (1)

luis_a_espinal (1810296) | about 4 months ago | (#47757667)

'Imply' means something different in formal logic.

we're talking about the real world, so the formal-logic definition of imply doesn't apply. It only makes sense in math. Imply in real-world terms means hint at.

Just because the real world is full of illiterate people, that does not mean the precise meaning of words suddenly vanish. The mindless masses murder the language all the time using the wrong words to express what they want to say (if they even had the capacity to build a cogent statement).

"Imply" is "imply" and it is distinct from "hint" - check your dictionary. Yes, real world people are too stupid to use a dictionary, but that doesn't invalidate the definitions in it.

You can use this line instead: "Just because two things happen at almost the same time doesn't prove that the first one caused the second."

That's a different statement. If A doesn't cause B but there is a C that causes both, this is a causation. Of course our measurements for A and B could still be correlated without any causal relation that connects them, but that's improbable.

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47754111)

You don't have to say "Correlation does not imply causation!". We already understand this.

What you fucking children that shout "Correlation does not imply causation!" in response to every study don't seem to nuderstand is this:
There are a reasons why we look for correlations.

First is that for many things, if not almost everything that happens, it is not obvious how it works. We simply don't know the details of how it works.
You cannot determine causal relationships in evolution from first principles, writing syllogisms, logical deductions, ABA testing or whatever because no one saw it happen. No one was there to record the data. No one was there to conduct experiments.

Secondly, we look for correlations because when you have a causal relationship, then there will always be a correlation, and if there is not correlation, then there is not causal relationship. it the starting point for figuring how things work.

Stop bothering the grownups. Seriously.

Re:not so fast (2, Interesting)

Anonymous Coward | about 4 months ago | (#47754125)

RE "Correlation does not imply causation!"

You are wrong. Correlation does indeed imply causation.

If you had said "Correlation does not prove causation!", then I would say you are correct.

Re:not so fast (2)

Your.Master (1088569) | about 4 months ago | (#47754439)

In the formal logical sense, imply means prove. That comes from its formal logical definition: http://whatis.techtarget.com/d... [techtarget.com] .

You are using "imply" in a more casual sense, which would be fine if you didn't also call him wrong. Now that you've broken out the weird pedantry, I have to tell you he's not wrong, he's actually perfectly accurate and you're being pedantic.

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47754447)

Yes it does. When two items are correlated in a statistically significant way, this often means that there is some (not necessarily straightforward) causal relation between them. Stop screaming and rephrase your statement.

Re:not so fast (1)

wonkey_monkey (2592601) | about 4 months ago | (#47754669)

Just because there is a correlation it DOES NOT mean that there is causation!

Just because someone implies a causation doesn't mean they've automatically made the mistake you're raving about.

Did you, perhaps, try reading the paper to understand why this claim is being made?

Re:not so fast (1)

tsqr (808554) | about 4 months ago | (#47756033)

Correlation does not imply causation!

Well, maybe. [xkcd.com]

Re:not so fast (1)

Will.Woodhull (1038600) | about 4 months ago | (#47756357)

You missed one:

Correlation does not imply

Ah, fuck it. Multiple repetitions of a meme does correlate with poor language skills and a consequent inability to express anything of value.

Beyond that, there is nothing more to say.

Re:not so fast (1)

Dutch Gun (899105) | about 4 months ago | (#47753611)

Growing to adult size by age 7 might be detrimental to survival.

Really? That hypothesis doesn't make a lot of sense to me. Larger and stronger at a younger age would seem to be a good survival trait, not a bad one. It doesn't seem like the benefits of parental protection instincts for young children would outweigh the negatives of being weaker and smaller, purely on the basis of survival traits. Besides which, I don't think parental protection instincts necessarily disappear when a child reaches adulthood. Talk to my mother if you're not convinced.

Still, it doesn't seem as simple as the brain using up too many nutrients either, for the obvious reasons you describe. If it was regulated by diet, then it seems we should be able to adjust growth in the same way, and that doesn't happen - although long-term growth is certainly affected by diet. It's certainly true the brain is an "expensive" organ in terms of nutrient consumption, but I think there are other regulating factors as well which we just don't understand yet.

Re:not so fast (5, Insightful)

Dahamma (304068) | about 4 months ago | (#47753769)

The evolutionary reality is even simpler that that (though the achievement of those is clearly not). The three main factors are:

1. be able to reproduce
2. be able to attract/acquire a mate
3. be able to care for/protect offspring long enough for them to reach #1

Clearly if it was just up #1 we would still be living alongside the rest of the primates. #2 can be a fairly complex social interaction - but insects are just as capable of it as humans. #3 is where the whole thing explodes, and is the key to investing all of those resources into the brain (and is what made it more evolutionarily advantageous to extend the time to #1 and #2).

Though of course in modern human society, social and technological advancement in #3 has so outpaced the first two that they barely seem to matter, and is why we are basically blowing past any "natural" population control. Our brains are letting us find clever ways of surviving and stripping the planet of resources, but unless we figure out a way to expand beyond the planet or stop using its finite resources we'll go through the same collapse seen in any other species going through a population explosion...

Re:not so fast (1)

Oligonicella (659917) | about 4 months ago | (#47753793)

Larger and stronger at a younger age would seem to be a good survival trait, not a bad one. It doesn't seem like the benefits of parental protection instincts for young children would outweigh the negatives of being weaker and smaller, purely on the basis of survival traits.

It is axiomatic that, as far as Homo sapiens is concerned, evolution disagrees with you. I believe the reason is you limit what survival traits are to less than what they truly are.

Re:not so fast (1)

wvmarle (1070040) | about 4 months ago | (#47753805)

Humans are by far the most intelligent creatures on this world, and thanks to that intelligence can learn a lot.

Learning primarily takes place in the childhood stage, when parents directly teach their children all they need to know to survive (which until not so long ago, was indeed mostly survival skills: how to grow your own food and so). A long childhood (and with that, long parental care) may for this reason be an advantage: longer time to learn typically makes for a better end result.

As another poster pointed out, childhood is not the most robust stage of the life cycle of a human, especially early childhood. And even if parental care during childhood improves survival during that stage of life, it's genetically not exactly a productive stage of life - no procreation yet, so surviving that part is great but it doesn't necessarily help to spread those presumably beneficial long childhood genes in the overall population. Procreation tends to happen when the parental care has finished.

Re:not so fast (2)

jandrese (485) | about 4 months ago | (#47753827)

This doesn't really follow. Animals that suddenly find themselves an abudance of food don't grow massive, rather they reproduce in greater numbers. If food were always highly available then we might select for large size and big brains over time, but any one person with too much food is not going to suddenly become superman.

I'm not an expert in this, but my guess is that our energy hungry brains are one of the factors in the relatively long development period for our offspring, but it's not the only factor.

Re:not so fast (1)

rogoshen1 (2922505) | about 4 months ago | (#47754425)

Well, glucose in the blood is basically a toxin; by overfeeding carbohydrates you're really just taxing the bodies ability to cope with blood sugar (IE, insulin spikes and making you fatter).

The brain has its own needs, and will take what it needs basically no matter what. Not enough dietary carbohydrates to provide glucose? No problem, some of your muscle (or protein from our diet) is broken down and converted by the liver. Bear in mind the amount of glucose the brain needs per hour, and the fact that at any given time you have around 2 teaspoons of glucose circulating... the body is very very (very) good at preventing the brain from running out.

Re:not so fast (1)

asmkm22 (1902712) | about 4 months ago | (#47754515)

You assume the body can process as much glucose as you can feed it, which simply isn't true. There's a point where any glucose beyond this threshold is "wasted" for the purpose of positive development, but it does still get processed (into fat). Put another way, the a child's body is a machine that can process 100 units of glucose (arbitrary number) at any given time, 80 of which go to the brain. If you feed it 120 units of glucose during that time, it still only processes 100. Again, 80 goes to the brain, 20 goes to other uses, and the excess 20 probably goes to the gut.

Re:not so fast (1)

LWATCDR (28044) | about 4 months ago | (#47756099)

"If that were the case, kids who are overfed carbohydrates would be smarter and taller, not fatter and dumber."
Every look at an AP class? Fatter does not mean dumber.
Of course the best combination might be a high carbohydrate and a high activity diet for young people.

Re:not so fast (0)

Anonymous Coward | about 4 months ago | (#47757107)

The opposite could be true: Kids with overdeveloped physiques who engage in high levels of physical activity (who can consume 5000 or more calories a day and use it) cause their bodies to rob the brain of the energy needed to develop. As a result, jocks are dumb.

Re:not so fast (1)

operagost (62405) | about 4 months ago | (#47756235)

If that were the case, kids who are overfed carbohydrates would be smarter and taller, not fatter and dumber.

Now who's drawing premature conclusions!

Here's the legendary Slashdot car analogy. Put an 850 CFM Holley on a straight six in a 1960s Pontiac Lemans. Will that turn it into a GTO? No! The human body can't process those calories any faster. They have to be changed into glucose.

Your implication that being overweight makes kids dumber is so stupid, I wonder what your motivation is.

Re:not so fast (1)

arth1 (260657) | about 4 months ago | (#47757287)

The human body can't process those calories any faster. They have to be changed into glucose.

They already have been changed to glucose before they become fat, which means that the body quite obviously could process them. That they became fat is because there weren't any takers for the glucose.

Re:not so fast (1)

jellomizer (103300) | about 4 months ago | (#47756887)

Wow! I can't believe such an ignorant comment was a +5 insightful.

1. The correlation between obesity and intelligence doesn't seem to have a connection. There is a stronger correlation between obesity and poverty and poverty with low test scores. But that is chaining a bunch of consolations together to come up with a faulty premise. You will need to compare Intelligence of Fat vs Skinny people in similar economic environments.

2. Obesity is a factor of over use of a nutrients, not a normal healthy usage. Just like too much of any nutrient will at some point be harmful, as it is more then the body needs. Humans in particular do crave sweets more then other animals, because we do need the sugar more then other animals. But to say if we eat a lot of sugar we will become taller and smarter is rather stupid, as out body needs to regulate it. Fat as well comes from having excess calories sugar and white carbs have a lot of empty calories. So while the good parts of the sugar may go to good use, when there is too much the calories will just add up.

Our body isn't about if a little is good for us then a lot must be better. However obese kids do tend to start puberty at a younger age, so the sugars may be causing parts of them to mature faster.

Re:not so fast (1)

arth1 (260657) | about 4 months ago | (#47757201)

Wow, I can't believe that someone missed the point so completely!
The point being that it is unlikely that the brain is stealing the glucose and thus stunting growth like the article supports, because when kids are fat, that means they have metabolized carbs->glucose->fat, and thus have had plenty of glucose. That fat kids' bones don't appear to shoot past normal kids in growth strongly suggest that there are other reasons why kids don't grow physically to adults in half the time.

I suggest that being smaller and having different proportions to adults triggers the "do not harm" and "protect" instinct in most adults, thus increasing the chance of reaching adulthood and bringing one's genes on.
There are probably other survival advantages, like having less mass and more flexible bones might be adventageous at the age one learns to climb trees and cliffs.
When reaching the age where one is going to procreate and bring up own children, the advantage is to have a more adult body, capable of hunting, foraging, carrying and protecting.

Get it now, or are you going to get sidetracked by a single word again?

Possible related factors (1)

PapayaSF (721268) | about 4 months ago | (#47753567)

There are other related factors that seem to fit.

  1. Humans also have a lot more to learn than other primates: e.g. language and culture. It makes sense that we evolved with extended childhoods to give us time to learn things.
  2. Neoteny: [wikipedia.org] It's well-known that humans have an innate attraction for the general proportions of children: small, with big eyes and a large head. The longer kids look like kids, the more likely parents and other humans are likely to nuture, protect, and teach them.

Precious Moments (1)

tepples (727027) | about 4 months ago | (#47754047)

It's well-known that humans have an innate attraction for the general proportions of children: small, with big eyes and a large head.

That explains the popularity of Precious Moments [dragoart.com] and other super-deformed [orain.org] franchises. The problem with that in real life, of course, is that it's harder for a big head to fit out mama's birthin' hole [orain.org] . Bulldogs already have big enough heads to run a serious risk of cephalopelvic disproportion [ufaw.org.uk] .

Re:Possible related factors (1)

Jack Griffin (3459907) | about 4 months ago | (#47754451)

The candle that burns twice as bright takes twice as long to light, or some shit...

More soda for all my friends (0)

Anonymous Coward | about 4 months ago | (#47753647)

So, I guess giant soda's filled with sugar should cure that problem in no time.

Pretty obvious (1)

jtownatpunk.net (245670) | about 4 months ago | (#47753673)

Gotta milk that free ride as long as possible.

that doesn't hold up... (1)

Anonymous Coward | about 4 months ago | (#47753713)

... we have been feeding children tons of sugar in US and they don't seam to grow faster.

Re:that doesn't hold up... (0)

Anonymous Coward | about 4 months ago | (#47754465)

... we have been feeding children tons of sugar in US and they don't seam to grow faster.

Instead they burst at the seems faster.

slow growth humans (1)

turkeydance (1266624) | about 4 months ago | (#47753777)

just another effect of climate change. 30 is the new 16, dude.

It's always been a badge of the upper class (0)

Anonymous Coward | about 4 months ago | (#47753787)

To have wives and teenage and sometimes adult children who are pampered and useless, contributing good appearances (hopefully) but little else.

Critical Path (5, Insightful)

Livius (318358) | about 4 months ago | (#47753897)

I would speculate that it's simply that, for humans in their eusocial foraging societies, brain development was the priority and there was no point in reaching sexual maturity and adulthood before the brain had developed and the individual had learned enough to be a full member of the community. The brain and the rest of the body are not competing for glucose, the brain is simply the critical path and the rest of the body has no need to develop faster.

Re:Critical Path (0)

Anonymous Coward | about 4 months ago | (#47754147)

I agree with what you are saying. However, eusocial is the wrong word; humans are not an eusocial species. AFAIK, the only eusocial vertebrates are the mole rats.

Humankind and eusociality (5, Interesting)

tepples (727027) | about 4 months ago | (#47754241)

humans are not an eusocial species.

I decided to fact check this claim. Eusociality, according to Wikipedia and the references it cites, is defined as three aspects of the behavior of a species:

  • "cooperative brood care (including brood care of offspring from other individuals)": Daycare is a thing.
  • "overlapping generations within a colony of adults": Grandparents are a thing.
  • "a division of labor into reproductive and non-reproductive groups": Humankind appears to be moving in the direction of breeder vs. thinker classes. More affluent classes already tend to produce fewer children, and the public has become more accepting of a gay lifestyle. Furthermore, I've seen plenty of contempt for "breeders" and other childfree-by-choice advocacy on Slashdot.

I agree that humans are not as close to the eusocial ideal as bees and mole rats, but we're closer than a lot of other species.

Re:Humankind and eusociality (1)

NoImNotNineVolt (832851) | about 4 months ago | (#47756249)

Furthermore, I've seen plenty of contempt for "breeders" and other childfree-by-choice advocacy on Slashdot.

Breeders are morally bankrupt, selfish assholes. Join the Voluntary Human Extinction Movement [vhemt.org] today!

So that means.... (1)

Whiteox (919863) | about 4 months ago | (#47753913)

So that means that tall gangly kids are stupid?
Disclaimer: I'm short and a genius :)

I'm really not buying it (3, Interesting)

Michael Woodhams (112247) | about 4 months ago | (#47754129)

For most species, childhood is all risk, no benefit (where benefit = breeding), and so it is to be got through as fast as possible (or at least in time for next breeding season). If glucose shortage was the only reason for doubling the length of our childhood, there would be a huge evolutionary pressure towards kids who could metabolize much more food and reach adulthood in half the time.

There is an obvious reason why humans have such a long childhood - it is because we have so very much to learn. Little bodies can learn as well as big bodies, and cost less to maintain.

Re:I'm really not buying it (1)

phantomfive (622387) | about 4 months ago | (#47754603)

For most species, childhood is all risk, no benefit (where benefit = breeding)

Unless the benefit is that the older generation can live longer, and gain more wisdom, before the younger kids become......teenagers.

That is, the race would benefit from the greater wisdom of older folks, not individuals.

Wrong (but still the brain's fault) (2)

penguinoid (724646) | about 4 months ago | (#47754187)

If it is the brain stealing calories that slows development, how come when you feed a child a high-calorie diet he becomes a fat child rather than a young adult?

How about this: if we took only three years (or less!) to reach adulthood like some animals, you'd have toddler with an adult body. I'm pretty sure it's actually an advantage that our young are easily restrained. It's actually rather common for more intelligent creatures to take longer to mature. Taking longer to prune the excess synaptic connections seems to allow for greater learning at the cost of slower development. In the case of humans, we're also born with an especially undeveloped brain and a squishy skull, for which your mother is probably grateful.

Re:Wrong (but still the brain's fault) (3, Insightful)

wonkey_monkey (2592601) | about 4 months ago | (#47754691)

If it is the brain stealing calories that slows development, how come when you feed a child a high-calorie diet he becomes a fat child rather than a young adult?

Probably because "stealing calories" is just an over-simplified journalistic bit of fluff.

Consumption (0)

Anonymous Coward | about 4 months ago | (#47754269)

Pondering existence is expensive

I'm a small fry (0)

Anonymous Coward | about 4 months ago | (#47754295)

This explains why

These are some tasty apples...

typical slashdot responses (1)

asmkm22 (1902712) | about 4 months ago | (#47754535)

Leave it to the Armchair Slashdot Scientist crows dismiss a study and throw in their own contrary opinion.

Load of crap ... (0)

Anonymous Coward | about 4 months ago | (#47754941)

Look at any fat kid - plenty of glucose for 8 brains in that lard.
No you grow up slow because your body needs to not waste construction on something it cant control properly yet and which might even be risk to survival. (Baby with adult sized/strengthed body - much easier to break things and itself)

Always looked young (1)

Culture20 (968837) | about 4 months ago | (#47755193)

I've always looked young for my age; now I know why. Yes, my brain does use more glucose than most people's, ladies.

*Points to the human brain* (0)

Anonymous Coward | about 4 months ago | (#47755383)

Hideki!

Society also does this.. (2)

Lumpy (12016) | about 4 months ago | (#47755673)

WE have some wierd fetish with letting kids be kids for as long as possible. Sorry but at 13 you are biologically an adult so you need to have adult responsibilities and adult expectations. these teenagers need to get off their asses and work, build, etc.. Instead we extend this out to age 20 before we expect them to get a job and start being responsible.

Less than 100 years ago it was not uncommon for marriage at age 16 and that young couple working hard to build their family Average age of a woman getting married was around 21 years of age. Today it is far higher at 26 years of age and insanely uncommon for a 16 year old marriage, Although outside the USA it is far lower. Mexico has a median for women at around 18 years old. Many states in the USA still have the age of consent at age 16. This means that 16 year olds can make decisions as an adult, yet for some reason we think they cant today and are still children.

Note on marriage ages, some of this is economics, back 100 years ago it was a lot easier to make a living as you made about $35.00 a month working at a foundry or smelter and typically renting a house is $5.00 a month less that 20% of your income was your rent. today most of the young pay 60% of their income as rent and have to split that rent with room mates because they can not even hope to even meet rent with their meager income. So 100 years ago it was easier for young and uneducated to make it in the world with the sweat of their brow.

Re:Society also does this.. (0)

Anonymous Coward | about 4 months ago | (#47757755)

13 Hell, We need to teach them about the real world from the time they're born. As soon as they can walk and talk, they are more than capable of doing most blue collar jobs in America. Leave school for the rich kids. By 13, if they can't work a 16 hour day and bring home a steady paycheck, they don't deserve to live! Like they used to say on the farm, "You want to eat, you better work!" You want to get rid of childhood obesity, force them to put in 16 hours, if they want dinner.

I am personally sick of all this crap about "recess" and "play time" and "summer vacations". I've never had a vacation in my life. I certainly never had "play time." We would do 16 hours on the farm in spring and summer, and fall and winter we spent in the mines. That is the West Virginia way. At least it was until all that touchy-feely crap in the 70's. Even in college in the 70s, I took night classes so I could still work the farm and mines and even then I was called a lazy bastard for only working 10 hours because of sissy school work.

I say we abort them all and start fresh with a generation of kids who know what real work is. "Wah Wah 40 hours a week is so hard boo hoo. I want to watch Sesame Street and eat candy wah!" These lazy kids need to do the right thing and jump off the roof so their families can collect the insurance money. At least then they would have contributed something!

Re:Society also does this.. (2)

geekoid (135745) | about 4 months ago | (#47757905)

"Sorry but at 13 you are biologically an adult s"
false.

Re:Society also does this.. (0)

Anonymous Coward | about 4 months ago | (#47758063)

can they have or make babies? yes? then they are.
Lumpy is correct, you are wrong.

Re:Society also does this.. (2)

prgrmr (568806) | about 4 months ago | (#47757943)

So many poor assumptions there. The average life expectancy was a lot less 100 years ago: http://demog.berkeley.edu/~and... [berkeley.edu] Consequently, people got married earlier because they died sooner; this goes back through the beginning of recorded history, and it was really only in post-WWI 20th century that marrying while a teenager became not just not the norm, but socially frowned upon. Also, look at the drops in life expectancy in 1918 and 1943; what you are seeing it the effects of both world wars and the spanish influenza epidemic in 1918. So life wasn't just short, it was unpredictably precarious in a very real, life-limiting way.

While there are definitely observable fetish aspects to the celebration of youth in our current culture, we no longer marry immediately post-pubescent because, for the very most part, we no longer need to as a practical necessity to be able to have family or an otherwise "full life".

You assumptions on economics are so bad they border on ridiculous. Up until the 1920s, 30 percent or more of the US population were farmers: http://www.pbs.org/wgbh/amex/t... [pbs.org] And yes, as the percentage of workers in agriculture declined, those in manufacturing rose; however, the real economic differentiator remains education, and that trend has only been slowly improving: http://en.wikipedia.org/wiki/E... [wikipedia.org]

Re:Society also does this.. (1)

Lumpy (12016) | about 4 months ago | (#47758085)

Where were the population centers? How many farmers lived in NYC?

30% were farmers so 70% were not farmers. Thus the Bulk of workers were NOT farmers.

I learned 2 things from the summary (1)

Anonymous Coward | about 4 months ago | (#47755889)

I learned 2 things from the summary

  1. Humans grow up - really? Don't see much evidence for that these days.
  2. Brain development detracts from maturing - so why are there so many stupid adults?

wrong (1)

slashmydots (2189826) | about 4 months ago | (#47756051)

This article is incorrect, as everyone else said. Eating more sugar doesn't make you grow faster so it's wrong. If children grew any faster, their bones and joints wouldn't take the stress. My evidence is kids who grow too fast and have bone and joint problems (duh). Also, if they grew any faster, they were be even less coordinated due to limb length alterations and prone to accidental injury or death.

Re:wrong (1)

geekoid (135745) | about 4 months ago | (#47757939)

" Eating more sugar doesn't make you grow faster so it's wrong. "
where does the paper say that?

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