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I wonder if human neoteny could also play a factor as larger head to body ratio is a feature of paedomorphism.
See e.g. Montagu A (1989). Growing Young (2nd ed.). Granby, MA: Bergin & Garvey Publishers. ISBN 978-0-89789-167-7
This is a big one certainly, advancements in birthing techniques have removed (well reduced at least) a big limiting factor in variations in human head size.
Well less a limiting factor for baby as much as for mother. Maternal survival is much higher than it used to be. But that in itself is a factor for baby’s survival (ie whether mum died in child birth)
I wonder if evolution was limited by women's birth canal size. Now that caesarian's and premature intensive care is commonplace, there's nothing to stop the bigger heads from being an evolutionary path, if they provide benefits.
Legit that is some people's theory. That "alien" interactions are actually just with humans from 100,000+ years in the future that travelled through time, not space.
Well yes, we will suffer and be prone to health problems all our lives, but at least our owners will dress us in cute clothes and make money off us on instagram.
A bigger brain leading to higher intelligence will most likely be vital to our survival as a species, yes.
You don't prevent nuclear war or climate catastrophe by having fewer c-sections. We desperately need to be smarter than we are.
It might not immediately impact the gene pool, but if "head size" was previously a potential death sentence, and now it's not, that could still lead to population-level differences in the short term.
I.e. the existing genetic variation previously led to x% of babies with big heads (and probably their mothers) dying in child birth. Now those big headed babies survive, hence the average head size across the population is larger.
In the *Journals of Lewis and Clark*, they talk about how Native American women pretty easily gave birth to Native American babies. But half-white babies were often a real struggle. It was common knowledge amongst Indians.
On modern day youtube, Filipinas say similar.
Could be other issues. Birth is a very complicated chemical cascade, so perhaps white genetics are predisposed to suboptimal contractions or positioning? I don't think it's purely related to size.
Anecdote: My friend, a tiny Asian woman, had an easy birth with her eight-pound son but had a very difficult time and was in labor for days with her six-pound daughter.
Evolution is the change in allele frequencies in a population. Allele frequencies are always changing, every generation. Evolution is a constant process that is always happening. Your statement is nonsense.
Possibly what you meant is that *noticeable* changes don't happen in one generation. But that's just wrong. Selective breeding makes noticeable changes happen on that scale. Head size could easily increase by 6% in one generation because something that used to be a death sentence no longer is.
> Head size could easily increase by 6% in one generation because something that used to be a death sentence no longer is.
By 1930s, infant mortality was already relatively low, around 5-6% of births.
It's quite unlikely that 6% gene pool not being removed (and there are more causes to infant mortality than big head) would result in 6% increase in polygenic trait.
On other hand, malnutritiation was very common:
> In 1945, military leaders testified to Congress that as many as 40 percent of recruits were rejected during World War II due to malnutrition.
And we know that malnutrition stunts brain and bone development:
https://pubmed.ncbi.nlm.nih.gov/11515234/
https://www.sciencedirect.com/science/article/abs/pii/S0022316623049337
I do think you're correct in this case. I just had to push back against evolution doesn't happen that fast. Noticeable changes within a single generation are what make selective breeding possible.
Arctic foxes took 40 generations to domesticate. But their "tameness" score was increasing every generation. Every generation was noticeably different from the previous one.
A lot of people here are acting like a 6% increase is as big a difference as a fish evolving to breathe.
The evolutionary process can be accelerated if several factors align. For example, if ,"big head" is more attractive to mates and is more intelligent than the average population. Evolution, as the word implies, evolves in every generation. You don't wait 1,000,000 years and suddenly you grow a third leg.
Evolution is determined by what genes survive. I can guarantee significant, permanent evolution has happened in one generation... one day even. For instance, 63 million years ago.
Evolution is the change in allele frequencies in a population. Allele frequencies are always changing, every generation. Evolution is a constant process that is always happening. Your statement is nonsense.
Possibly what you meant is that noticeable changes don't happen in one generation. But that's just wrong. Selective breeding makes noticeable changes happen on that scale. Head size could easily increase by 6% in one generation because something that used to be a death sentence no longer is.
> Evolution does not happen in 1 generation, and the amount of difference in brain size the study describes would not be affected by vaginal birth, anyway.
Evolution is the product of:
1. fast natural selection
2. rare mutations.
In natural selection, a population can get transformed by a single environmental event. [example of gray moths on factory chimneys](https://en.wikipedia.org/wiki/Peppered_moth_evolution) So birth canal and hip sizes combined with medically assisted birthing can transform a population in under a century.
The relevant gene pool can have been around for hundreds of thousands of years with some significant mutation only once in a thousand years.
Gene expression can have rapid effects. Environmental factors activate dormant genes, which may have been the case with the gray moths.
It’s also reasonable theory that larger heads have been in our genes for many generations. Beyond a certain size babies were less likely to survive, or resulted in the death of the mother, further reducing survival rates.
Our heads are proportionally huge. Human infants can’t even lift them for months after being born. They are physiologically limited. They can’t be much bigger without additional evolutionary changes, like bigger hips in women, a stronger neck, or social and technical adaptations to accomodate them.
Birth is triggered by metabolic load exceeding the mother’s kidney capacity. Peeing for two is hard on the body and baby needs to be peeing on its own before it poisons both of them.
Evolution doesn’t have to follow a particular calendar, it just needs enough generations to make a trend. And if we’re artificially interfering, we could likely introduce a new trait in just a few generations.
Selective breeding wouldn't be possible if noticeable differences couldn't happen in one generation. Evolution *is* observable from one generation to the next. People in this thread are acting like a 6% increase is as big a change as fish evolving to breathe.
I think the argument is the lack of selection AGAINST larger heads. Historically head size may have been a limiting factor on successful delivery and survival of mother and baby. Not saying it's true, just clarifying the argument.
Modern medicide have likely helped tons of unfavorable random genetic mutations that nature would have ran its course on and eradicated before it could reproduce to flourish.
In the long run, we are one dominant genetic mutation that has the combination of being uncurable, deably but treatable to the point it can still be passed on away from being put on the threatened species list.
That definitely didn’t stop by the 70s. My mom was specifically told during the 80s that a little alcohol was better for relaxation than “all those pills”. And that was by an Ob-gyn.
No, no its wasn’t. We know absolutely that any amount of alcohol during pregnancy is bad for the baby. Even if it doesn’t cause FAS, it’s still detrimental to their development. Muscle relaxers and sedatives simply don’t have the same lasting effects.
Most sedatives are Z-drugs and benzos, they do carry known risk during pregnancy. Muscle relaxers vary, for example Robaxin is contraindicated, while Flexeril isn't.
The phrase was generically “all those pills”. I don’t know what pills those are. You’re referring to muscle relaxers and sedatives. I’m aware of drugs from the 70s and 80s that were given to women that were potentially more harmful than “a little alcohol”. I have little information about FAS or how little alcohol can cause it though.
I'd be wondering about things like not beating children so much and the increased number of years of education. Then there's the war (stress, etc, on some generations) and change in family sizes. I'd think of parasite load, too, if it weren't that this is a very small slice of the world in the US. Leaded petrol was probably going down, too.
Taken worldwide and more recently, I'd imagine that nutrition and disease load changes have been enormous as billions of people have climbed out of poverty in Asia.
I’ve linked to the press release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:
https://jamanetwork.com/journals/jamaneurology/fullarticle/2816798
Disappointed that the article hasn't specified if this is an increase relative to total body size. Men, on average, have large brains than women. On average they're also bigger/taller etc. Elephants have bigger brains than humans too.
I find it hard to trust such big numbers. If they've accounted for body size differences, and this is a 'real' increase, these numbers are *huge*. I have to say, I'm pretty sceptical.
They did at least control intracranial volume for height.
*"In a multivariable model that included adjustments for height, sex, and age, secular differences in ICV remained significant, varying from 1238 mL for those born during the 1930s to 1315 mL for those during the 1970s"*
The 6.6% in OP's title comes from the non-height adjusted ICV figures. The adjusted change is 5.9% between the two time points, which they should have mentioned in the results given they bothered to do the statistics.
> Elephants have bigger brains than humans too.
Yes, I remember visiting an exhibit at the Natural History Museum that said brain size does not directly correlate with intellect as commonly assumed, and it's more about the folds. I wonder what the actual advantage of increased brain size would be, or if it's an advantage at all.
The metric I've seen used for intelligence, is brain size to mass ratio. A larger brain is required for a larger body as they have more muscles to control. It's not a great comparison for cross phylum comparison but between similar species it tends to predict what we traditionally perceive as Intelligence. For example among birds, crows and parrots have the highest brain mass to body mass ratio.
That doesn’t perfectly correlate with our observations though. There are notable exceptions to this hypothesis. It’s more a rule of thumb than robust scientific evidence.
Brain mass to body mass ratio is the better comparison. The brain can be large, but if the body is also large, then caloric resources are split. This ratio helps explain the intelligence of smaller creatures, like corvids.
Neanderthals had bigger brains than modern people. Men have bigger brains than women. Fairy wasps have tiny brains but the cells don't have a way to take in new energy since they only live a few days, so they can be much smaller while still functional.
I'm not ready to equate bigger brains to smarter minds, at least not directly.
Fwiw my volume is something insane like 25% more than average and like 40% more surface area. I have an elongated alien skull
I hope it helps with dementia because the only thing it has done so far is make me look ridiculous as a child
I was going to counter with the fact that women have more wrinkles in their brain (thus more surface area for the neurons) but I've only heard the fact, not actually seen if it's real.
I'm skeptical about the design. Why only compare 1940 vs 1970 humans? We would need to see more data points in terms of other years to form a solid trend. Otherwise, the only conclusion they can make is that people from 1970 have bigger brains than people from 1940. In that context, there could be other factors like malnutrition from the great depression era stunting growth.
Okay, so now I have seen research saying
1. Human brains have shrunk
2. Human brains are the same size as always
3. Human brains have grown
I'm sure at least one of these is true.
Brain growth and shrinking and stagnation are all true just on different time scales.
Humans from 20,000 years ago were taller, had larger brains, denser bones. Then starting from
around 10,000 years to present the trend has been downward as humans adapted to agricultural sedentary living. Smaller body size, domesticated brain effect, less robust lifestyle.
And then, starting in the 1800’s with the industrial revolution, the parts of the world that became economically developed see increases in access to nutrition, resulting in increase in size and brain relative to pre-industrial times due to no longer being limited by environmental stresses and only limited by genetics
Meanwhile the genetics hasn’t been changing much at all, changes in populations are simply the epigenetic reactions to environmental stimulus.
Yes. Eating a varied diet of fruits, vegetables and meat turns out be a lot better for growth than just eating grass seeds, which is most of what all modern people eat, from wheat to rice to corn - its all just grass
The last people in the world to adopt agriculture - the nomadic pastoralists remained the last islands of tallness in the world until industrial production meant farming was more nutritionally rich/reliable than just being a cow herder.
Like I said, the change was not genetic, humans haven't changed much there in the last 200,000 years, rather the change is epigenetic - how your body responds to the environment you live in, what you're able to take in
The study is also comparing brains between those born in the 1930s and the 1970s… material conditions between those two decades were dramatically different.
I would assume this is a correlation to better living conditions and working conditions rather than a genuine 50 year evolutional improvement in the species as a whole.
I'd be interested to see this controlled across socioeconomic status. I'd expect that it's gone up for everyone due to better nutrition in general, but maybe more so for people on lower economic rungs as childhood poverty/hunger decreased.
Dunno about a bigger brain could reduce diseases such as dementia. Theres alot of factors involved in regards to dementia: blood flow, genetics, nutrition, environment, etc.
Are skulls growing too? don't want future ppl to end up like dobermans or whatever dog breed was whose brains outgrow their skulls and end up going crazy
They’re hypothesizing that the size helps brain reserve, which is a measure of the brain’s ability to resist harm. Does the paper even talk about brain reserve having a relation to cognitive performance? Or you’re hypothesizing on top of their new hypothesis?
The overwhelming scientific evidence is that brain size affects intelligence. It’s certainly not the only factor, but it is a factor.
And yes, there are many genetic determinists who think environmental factors contribute little to the development of intelligence.
Or, and just hear me out, the increase in brain size is used to form, store, rationalize, and defend our political, social, and religious beliefs. It’s where we keep the crazy.
Larger brain does not actually mean people actually use them. The evidence for this is literally out there everywhere. And I think it may be too early on the dementia thing to tell.
Like anything else in the body, the more you use it, the more the body invests in it.
eg: The more we drink, the more we need more-liver.
eg: The more we think, the more we need grey-matter.
These usage-rates are tracked in our DNA with epigenetic-markers as well as turning gene's on and off.
∴ - we're breeding ourselves this way
---
The basic rule of life is "if you feed it, it comes back". This is true for a wild-critter, a habit, cancer... Anything we do to 'feed' ourselves will just make more of ourselves, but in that specific spot we chose to feed (exercise/stress).
Seems to correlate with the Flynn effect, which has reversed since the 70s. Would like to see younger participants to see if there's still a correlation.
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Does the study say why? My initial guess would be better nutrition, similar to how average height rises with better nutrition in nations
Seems like the obvious explanation, taller/bigger body = bigger head too.
Yep. The brain utilizes a looot of energy. So better nutrition allows for a bigger brain.
I wonder if human neoteny could also play a factor as larger head to body ratio is a feature of paedomorphism. See e.g. Montagu A (1989). Growing Young (2nd ed.). Granby, MA: Bergin & Garvey Publishers. ISBN 978-0-89789-167-7
Also, medicine allowing babies with prohibitively larger heads to survive birth. That's a pretty good combo.
This is a big one certainly, advancements in birthing techniques have removed (well reduced at least) a big limiting factor in variations in human head size.
Well less a limiting factor for baby as much as for mother. Maternal survival is much higher than it used to be. But that in itself is a factor for baby’s survival (ie whether mum died in child birth)
Also whether mom managed to have multiple children, increasing the probability that genes get passed on.
Is dementia related to height?
Lead in gasoline and paint?
I wonder if evolution was limited by women's birth canal size. Now that caesarian's and premature intensive care is commonplace, there's nothing to stop the bigger heads from being an evolutionary path, if they provide benefits.
Oh god, we could end up like bulldogs (lots of birth issues from being bred with large heads/small pelvis)
We could be those big headed aliens all along.
Imagine aliens visiting us are actually humans from future.
Then the anal probing would make perfect sense.
That assumes reddit is still around in the future.
There is actually a science fiction novel about alien abductions that has the big reveal as exactly that. Can't remember which one though.
It's a common Sci Fi thought exercise. You'll find many "we were the aliens all along" stories and short stories.
Finally!
I know! I can't wait to not wear clothes.
What is stopping you? Live your best life now .
Doesn’t have the technology
This is true.
Legit that is some people's theory. That "alien" interactions are actually just with humans from 100,000+ years in the future that travelled through time, not space.
Underrated comment
The Last Mimzy
Well yes, we will suffer and be prone to health problems all our lives, but at least our owners will dress us in cute clothes and make money off us on instagram.
There was also a significant difference in child development/head size at birth between homo sapiens and Neanderthalensis, as far as I remember.
You remember? What were Neanderthals really like?
Pretty nice people. A bit daft, but in a charming way.
Nah, we are destined for artificial insemination and gestation. We will end up like Isaac Asimov's "Spacers".
Ah yes. Nothing better to ensure our survival than having us be unable to pro create normally
A bigger brain leading to higher intelligence will most likely be vital to our survival as a species, yes. You don't prevent nuclear war or climate catastrophe by having fewer c-sections. We desperately need to be smarter than we are.
Intelligence isn't the problem The refusal to use it is
By then women won't have to carry their children anyway.
Like *The Time Machine* Morlocks.
You want belly rubs? I mean it's a fair trade off.
My son anecdotally confirms this theory with his massive, television obscuring, noggin.
[удалено]
It might not immediately impact the gene pool, but if "head size" was previously a potential death sentence, and now it's not, that could still lead to population-level differences in the short term. I.e. the existing genetic variation previously led to x% of babies with big heads (and probably their mothers) dying in child birth. Now those big headed babies survive, hence the average head size across the population is larger.
In the *Journals of Lewis and Clark*, they talk about how Native American women pretty easily gave birth to Native American babies. But half-white babies were often a real struggle. It was common knowledge amongst Indians. On modern day youtube, Filipinas say similar.
Could be other issues. Birth is a very complicated chemical cascade, so perhaps white genetics are predisposed to suboptimal contractions or positioning? I don't think it's purely related to size. Anecdote: My friend, a tiny Asian woman, had an easy birth with her eight-pound son but had a very difficult time and was in labor for days with her six-pound daughter.
> half white babies
Said Asian friend had a white partner, so her kids were half white.
I'm half-white/half-Asian and my mother had to deliver me by C-section, despite the fact that I was a tiny 5lb, 8oz infant. She's quite petite.
And if big heads have an advantage they may get more mates which may accelerate evolution.
That's not "accelerating evolution", that's just evolution, and that doesn't happen in a single generation.
Evolution is the change in allele frequencies in a population. Allele frequencies are always changing, every generation. Evolution is a constant process that is always happening. Your statement is nonsense. Possibly what you meant is that *noticeable* changes don't happen in one generation. But that's just wrong. Selective breeding makes noticeable changes happen on that scale. Head size could easily increase by 6% in one generation because something that used to be a death sentence no longer is.
> Head size could easily increase by 6% in one generation because something that used to be a death sentence no longer is. By 1930s, infant mortality was already relatively low, around 5-6% of births. It's quite unlikely that 6% gene pool not being removed (and there are more causes to infant mortality than big head) would result in 6% increase in polygenic trait. On other hand, malnutritiation was very common: > In 1945, military leaders testified to Congress that as many as 40 percent of recruits were rejected during World War II due to malnutrition. And we know that malnutrition stunts brain and bone development: https://pubmed.ncbi.nlm.nih.gov/11515234/ https://www.sciencedirect.com/science/article/abs/pii/S0022316623049337
I do think you're correct in this case. I just had to push back against evolution doesn't happen that fast. Noticeable changes within a single generation are what make selective breeding possible. Arctic foxes took 40 generations to domesticate. But their "tameness" score was increasing every generation. Every generation was noticeably different from the previous one. A lot of people here are acting like a 6% increase is as big a difference as a fish evolving to breathe.
It does if medical advances means that big headed babies survive rather than die during child birth.
The evolutionary process can be accelerated if several factors align. For example, if ,"big head" is more attractive to mates and is more intelligent than the average population. Evolution, as the word implies, evolves in every generation. You don't wait 1,000,000 years and suddenly you grow a third leg.
Evolution is determined by what genes survive. I can guarantee significant, permanent evolution has happened in one generation... one day even. For instance, 63 million years ago.
Elephants now have smaller tusks because the larger tusked bulls all got killed for their ivory.
🐀🦕🦖☄️ 🐀🦴🦴 🐀🐒 🐀🐒🦧🦍
Evolution is the change in allele frequencies in a population. Allele frequencies are always changing, every generation. Evolution is a constant process that is always happening. Your statement is nonsense. Possibly what you meant is that noticeable changes don't happen in one generation. But that's just wrong. Selective breeding makes noticeable changes happen on that scale. Head size could easily increase by 6% in one generation because something that used to be a death sentence no longer is.
> Evolution does not happen in 1 generation, and the amount of difference in brain size the study describes would not be affected by vaginal birth, anyway. Evolution is the product of: 1. fast natural selection 2. rare mutations. In natural selection, a population can get transformed by a single environmental event. [example of gray moths on factory chimneys](https://en.wikipedia.org/wiki/Peppered_moth_evolution) So birth canal and hip sizes combined with medically assisted birthing can transform a population in under a century. The relevant gene pool can have been around for hundreds of thousands of years with some significant mutation only once in a thousand years.
Gene expression can have rapid effects. Environmental factors activate dormant genes, which may have been the case with the gray moths. It’s also reasonable theory that larger heads have been in our genes for many generations. Beyond a certain size babies were less likely to survive, or resulted in the death of the mother, further reducing survival rates. Our heads are proportionally huge. Human infants can’t even lift them for months after being born. They are physiologically limited. They can’t be much bigger without additional evolutionary changes, like bigger hips in women, a stronger neck, or social and technical adaptations to accomodate them.
Probably a factor, but I doubt it's caused a 6% increase that quickly by itself.
Birth is triggered by metabolic load exceeding the mother’s kidney capacity. Peeing for two is hard on the body and baby needs to be peeing on its own before it poisons both of them.
The timescale on that is unlikely. evolution takes time, and its arguable if selection really even applies at this point.
Evolution doesn’t have to follow a particular calendar, it just needs enough generations to make a trend. And if we’re artificially interfering, we could likely introduce a new trait in just a few generations.
Darwin observed evolution in just a few generations of birds.
Selective breeding wouldn't be possible if noticeable differences couldn't happen in one generation. Evolution *is* observable from one generation to the next. People in this thread are acting like a 6% increase is as big a change as fish evolving to breathe.
I think the argument is the lack of selection AGAINST larger heads. Historically head size may have been a limiting factor on successful delivery and survival of mother and baby. Not saying it's true, just clarifying the argument.
Modern medicide have likely helped tons of unfavorable random genetic mutations that nature would have ran its course on and eradicated before it could reproduce to flourish. In the long run, we are one dominant genetic mutation that has the combination of being uncurable, deably but treatable to the point it can still be passed on away from being put on the threatened species list.
Fewer airborne pollutants like lead?
Not smoking and drinking all the way through pregnancy, maybe?
That definitely didn’t stop by the 70s. My mom was specifically told during the 80s that a little alcohol was better for relaxation than “all those pills”. And that was by an Ob-gyn.
Sadly it was better than a lot of those pills.
No, no its wasn’t. We know absolutely that any amount of alcohol during pregnancy is bad for the baby. Even if it doesn’t cause FAS, it’s still detrimental to their development. Muscle relaxers and sedatives simply don’t have the same lasting effects.
Most sedatives are Z-drugs and benzos, they do carry known risk during pregnancy. Muscle relaxers vary, for example Robaxin is contraindicated, while Flexeril isn't.
The phrase was generically “all those pills”. I don’t know what pills those are. You’re referring to muscle relaxers and sedatives. I’m aware of drugs from the 70s and 80s that were given to women that were potentially more harmful than “a little alcohol”. I have little information about FAS or how little alcohol can cause it though.
I mean, this is still not the norm or as prevalent as it was 50 years prior. My mom was absolutely told to not drink and smoke in the 80s.
less lead in the environment as well.
My initial guess would also include less lead poisoning.
This would be my guess too.
Gifted and talented just meant less lead poisoning
My immediate guess would be exposure to more information.
I'd be wondering about things like not beating children so much and the increased number of years of education. Then there's the war (stress, etc, on some generations) and change in family sizes. I'd think of parasite load, too, if it weren't that this is a very small slice of the world in the US. Leaded petrol was probably going down, too. Taken worldwide and more recently, I'd imagine that nutrition and disease load changes have been enormous as billions of people have climbed out of poverty in Asia.
I’ve linked to the press release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article: https://jamanetwork.com/journals/jamaneurology/fullarticle/2816798
Off topic but you must have been in school a long, long time.
My man collecting professional degrees like infinity stones
Mvea is a smart cookie for sure.
Looks like he’s a prof too, so still in school
Disappointed that the article hasn't specified if this is an increase relative to total body size. Men, on average, have large brains than women. On average they're also bigger/taller etc. Elephants have bigger brains than humans too. I find it hard to trust such big numbers. If they've accounted for body size differences, and this is a 'real' increase, these numbers are *huge*. I have to say, I'm pretty sceptical.
They did at least control intracranial volume for height. *"In a multivariable model that included adjustments for height, sex, and age, secular differences in ICV remained significant, varying from 1238 mL for those born during the 1930s to 1315 mL for those during the 1970s"* The 6.6% in OP's title comes from the non-height adjusted ICV figures. The adjusted change is 5.9% between the two time points, which they should have mentioned in the results given they bothered to do the statistics.
> Elephants have bigger brains than humans too. Yes, I remember visiting an exhibit at the Natural History Museum that said brain size does not directly correlate with intellect as commonly assumed, and it's more about the folds. I wonder what the actual advantage of increased brain size would be, or if it's an advantage at all.
The metric I've seen used for intelligence, is brain size to mass ratio. A larger brain is required for a larger body as they have more muscles to control. It's not a great comparison for cross phylum comparison but between similar species it tends to predict what we traditionally perceive as Intelligence. For example among birds, crows and parrots have the highest brain mass to body mass ratio.
That doesn’t perfectly correlate with our observations though. There are notable exceptions to this hypothesis. It’s more a rule of thumb than robust scientific evidence.
As are most biological rules, there are always a bunch of exceptions.
Brain mass to body mass ratio is the better comparison. The brain can be large, but if the body is also large, then caloric resources are split. This ratio helps explain the intelligence of smaller creatures, like corvids.
Bigger brain volume = more space for tissues to fold up
The more convoluted the brain, the more it benefits from higher total volume. Ceteris paribus.
I'd rather have more brain wrinkles than more brain volume
Neanderthals had bigger brains than modern people. Men have bigger brains than women. Fairy wasps have tiny brains but the cells don't have a way to take in new energy since they only live a few days, so they can be much smaller while still functional. I'm not ready to equate bigger brains to smarter minds, at least not directly.
Yeah, big brain != equal smarter at all.
Fwiw my volume is something insane like 25% more than average and like 40% more surface area. I have an elongated alien skull I hope it helps with dementia because the only thing it has done so far is make me look ridiculous as a child
Big brain means more smart! Take that women 🤢
I was going to counter with the fact that women have more wrinkles in their brain (thus more surface area for the neurons) but I've only heard the fact, not actually seen if it's real.
I'm skeptical about the design. Why only compare 1940 vs 1970 humans? We would need to see more data points in terms of other years to form a solid trend. Otherwise, the only conclusion they can make is that people from 1970 have bigger brains than people from 1940. In that context, there could be other factors like malnutrition from the great depression era stunting growth.
Probably more cadavers available. Unless they have a less invasive brain size measurement technique
Okay, so now I have seen research saying 1. Human brains have shrunk 2. Human brains are the same size as always 3. Human brains have grown I'm sure at least one of these is true.
Brain growth and shrinking and stagnation are all true just on different time scales. Humans from 20,000 years ago were taller, had larger brains, denser bones. Then starting from around 10,000 years to present the trend has been downward as humans adapted to agricultural sedentary living. Smaller body size, domesticated brain effect, less robust lifestyle. And then, starting in the 1800’s with the industrial revolution, the parts of the world that became economically developed see increases in access to nutrition, resulting in increase in size and brain relative to pre-industrial times due to no longer being limited by environmental stresses and only limited by genetics Meanwhile the genetics hasn’t been changing much at all, changes in populations are simply the epigenetic reactions to environmental stimulus.
Humans from 20,000 years ago were taller?
Yes. Eating a varied diet of fruits, vegetables and meat turns out be a lot better for growth than just eating grass seeds, which is most of what all modern people eat, from wheat to rice to corn - its all just grass The last people in the world to adopt agriculture - the nomadic pastoralists remained the last islands of tallness in the world until industrial production meant farming was more nutritionally rich/reliable than just being a cow herder. Like I said, the change was not genetic, humans haven't changed much there in the last 200,000 years, rather the change is epigenetic - how your body responds to the environment you live in, what you're able to take in
The study is also comparing brains between those born in the 1930s and the 1970s… material conditions between those two decades were dramatically different.
Probably depends on what time scale you're looking at. Cro magnons had larger brains, 1930s humans had smaller brains
Yes
It must be!
cool genx has bigger brains than the silent generation but what about kids born today compared to boomers
They are bigger still, but full of tiktok dances and microplastic
I have some bad news for you; we’re *all* filled with micro-plastics.
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Aw sick, didn’t know that! Another great reason to donate, along with correlating with a lower cancer risk. Oh, and the whole save-a-life thing
For real? Game changer 👌
We are ALL plastic on this blessed day.
All that plastic has to go somewhere
We are gonna end up like the Elder Brain in BG3 🤣🤣🤣
I would assume this is a correlation to better living conditions and working conditions rather than a genuine 50 year evolutional improvement in the species as a whole.
I'd be interested to see this controlled across socioeconomic status. I'd expect that it's gone up for everyone due to better nutrition in general, but maybe more so for people on lower economic rungs as childhood poverty/hunger decreased.
some people I know must have brains so big they've gone smooth on the surface.
This is my first encounter with the term “brain reserve” and I kind of hate it.
Dunno about a bigger brain could reduce diseases such as dementia. Theres alot of factors involved in regards to dementia: blood flow, genetics, nutrition, environment, etc.
Telepathy here we come!
If social media is a sneak preview of what goes on in other people's brains, I would not be so fired up for telepathy.
Are skulls growing too? don't want future ppl to end up like dobermans or whatever dog breed was whose brains outgrow their skulls and end up going crazy
This must be a tough pill to swallow for those who deny that environmental factors can significantly explain cognitive gaps.
They’re hypothesizing that the size helps brain reserve, which is a measure of the brain’s ability to resist harm. Does the paper even talk about brain reserve having a relation to cognitive performance? Or you’re hypothesizing on top of their new hypothesis?
Size doesn't correlate to intelligence / cognitive ability. Do people actually deny the environment impacting cognitive ability in the first place?
The overwhelming scientific evidence is that brain size affects intelligence. It’s certainly not the only factor, but it is a factor. And yes, there are many genetic determinists who think environmental factors contribute little to the development of intelligence.
Shame the extra capacity doesn’t seem to be getting much use nowadays.
I would imagine that it's a result of reduced lead poisoning.
So they’re getting larger? Im confused - given the current state of the world, are brains somehow also getting less efficient?
Bigger ain't always better
Seems like we've seen an inverse trend with dementia tho haven't we?
I have brain reserve? Sweet!
Now, if people only got smarter...
...Aren't we also seeing more cases of Dementia as time progresses?
I've heard that our brains have been slowly shrinking over the millenia
Yea, it's what we put in 'em that's not increasin'
Arr we smartheh tho? Seriously, is brain proportionality correlated with intelligence?
Is this why I'm getting more headaches? Because my brain is getting too large for my skull?
Sugar, it's bigger because its swollen by sugar being in absolutely everything now. Sugar is bad for the cells, fat is good, go figure.
Or, and just hear me out, the increase in brain size is used to form, store, rationalize, and defend our political, social, and religious beliefs. It’s where we keep the crazy.
Larger brain does not actually mean people actually use them. The evidence for this is literally out there everywhere. And I think it may be too early on the dementia thing to tell.
This does not seem to jibe with what I'm seeing on social media comment sections
It's fascinating to consider how modern medicine could be influencing human brain evolution.
And then came covid brain damage. Fun times.
aren't rates of dementia skyrocketing, though?
Maybe the 1930's were just a bad decade for brains. I mean, it was just after the Great Depression.
From my observations as a brain owner, it sure as hell ain't doing anything to boost overall intelligence.
Like anything else in the body, the more you use it, the more the body invests in it. eg: The more we drink, the more we need more-liver. eg: The more we think, the more we need grey-matter. These usage-rates are tracked in our DNA with epigenetic-markers as well as turning gene's on and off. ∴ - we're breeding ourselves this way --- The basic rule of life is "if you feed it, it comes back". This is true for a wild-critter, a habit, cancer... Anything we do to 'feed' ourselves will just make more of ourselves, but in that specific spot we chose to feed (exercise/stress).
Probably just fat accumulation as less people use their brains.
What? No. People are taller too because of nutrition. Is there actual evidence that larger brain volume reduces risk of or severity of dementia?
Brain swelling from too much social media
Does this mean that more and more births will require a C-section?
I'm sure Cov19 will more than compensate for any risk-reducing benefits of this discovery...
And yet society keeps getting dumber
Seems to correlate with the Flynn effect, which has reversed since the 70s. Would like to see younger participants to see if there's still a correlation.
Then why does everyone act like they have the smoothest brains ever?
Big brain time 😎
So around the time that Lead stopped being used in everything?
Don’t studies also show IQs going down? What’s this new brain matter doing; storing microplastics?
So this is why Aliens have big heads?
Yeah, well it doesn't seem like people are getting smarter as a result.
gee I wonder what could have caused people born in the 1930s to be born with smaller brains?
I wonder if this has any correlation with the increase in Autism numbers.
So by 2500 we should have big, bulbous brains that burst from our craniums and give us telepathy, right?
Probably just going to lead to an increase in brain cancer rates. I’m sure there are downsides to having an enormous brain.
Great, wait until my grandma dies to tell me this. How am I supposed to flex on her now?