Scientific data shows that the size of the human cranium has decreased and it stands to reason that the organ inside has shrunk too.
WHY IS THE HUMAN BRAIN SHRINKING?
From around 2 million until about 20,000 years ago the human brain increased. Then something happened and our brains started to shrink. Cro-Magnon (now the name has changed and you will see them called 'early modern humans', but I will still call them Cro-Magnon) man is estimated to have a brain that was 1500cc in volume, compared to an average man today who has a brain that is 1350cc. That is a loss the size of a tennis ball in just 10-20,000 years, an incredibly rapid shrinkage in evolutionary terms!
If this continues in the same direction at the same rate the brains of our descendants will soon be the size of Homo erectus! What is going on? Why is this happening?
CLIMATE CHANGE
One theory is that since the last ice age the human body has become smaller. Large, bulky bodies are better at conserving heat and so typically do a better job at surviving in cold climates. As the ice receded those large frames became more of hindrance due to the larger calorie needs to sustain them, and providing a benefit that was no longer as crucial.
But the Earth has warmed and cooled many times during our evolution over the last 2 million years and all the evidence points to a gradual increase in brain size during this period, so it might be partly to blame but not fully.
OUR DIET
Since the rise of agriculture happened during this period of shrinkage, could it be the cause? For most its existence, agriculture has been a hard way to eke out a life. Early crops were not nearly as bountiful as they became later on. It took thousands of years to change plants such as corn or wheat from the tiny wild grains that they were to what they have become today. It was also new, the knowledge to maximize the yield was not known and had to be pieced together over many generations. Same goes with farming technology, everything from the hoe to irrigation had to be invented and every little advance helped farming along.
Not only that, but a diet of mainly grains is lacking in protein and vitamins that are known to fuel the growth of the brain. Due to this malnutrition the brain and our bodies may have shrunk. This explanation doesn’t take into account areas where agriculture wasn’t used and people still hunted and gathered and these people have shown a decrease of the same magnitude in their brain size too.
DOMESTICATION
Animals such as dogs, pigs, turkeys and others have shown that their brains have decreased by 10-15% compared to their wild brethren. One of the main characteristics of domestication is reduced aggressiveness and experiments have shown that breeding creatures to be less aggressive results in more slender builds, smaller teeth, flatter faces, and a reduced cranial capacity.
In the wild you need every bit of brainpower to spot predators or food. When in captivity you don’t need to be as smart, and then it becomes a sort of ‘use it or lose it’ scenario over successive generations. In the wild, anything too dumb won’t be able to survive for long. It’s similar to how the weak or sick are the first to be picked off in a herd. It would also mean that humans have become domesticated.
IDIOCRACY THEORY
Similar to domestication, we have gradually moved into larger and larger societies. Earlier humans had to do everything themselves or at least someone in their tiny group had to have the knowledge and skills to perform the task. If these humans that were living solo or in tiny groups made a dumb mistake then they would pay for it, probably with their lives.
In a society, those that made dumb mistakes or were not smart enough to figure out how to do something could be supported by others in the larger group. Trade increased as well. Instead of having to have knowledge of everything required for survival, a person could specialize in one area and trade that skill for everything else.
Two researchers, Bailey and Geary, found that when populations were low cranial size increased and as population density increased the size of the cranium decreased. This has happened to populations all over the globe, as larger societies emerged the brains of people became smaller because they did not need to be as smart to stay alive.
So these individuals that probably would not have survived in the world of the Cro-Magnon are now doing so and breeding. Instead of being wiped from the gene pool, they have tainted it and have brought humanity down a notch.
One good thing about this though, is that even though our brains have gotten smaller the areas responsible for speech, reading and writing (things useful in a large society) have increased, which is nice.
MORE EFFICIENT
Since the bronze age the human brain has shrunk so rapidly that we would have to be the size of a pygmy to maintain proportional scaling. But researcher John Hawks has suggests that our brains have become smaller but have also become more efficient. He says that we have evolved to have a brain that gives us the most intelligence for the least amount of energy. It is estimated that our brain account for around 20% of the energy our body needs to function and we have just been evolving to get the maximum benefit from it, a sweet spot.
There would have to have been several extremely low chance mutations for this to happen, but as our population has increased in density it became more likely. He says his theory would account for many brain-related DNA mutations that have occurred over the past 20,000 years. Our brain’s wiring became more streamlined and our neurochemistry shifted so that we can do the same, or more, with less.
GETTING LARGER
Anthropologist Richard Jantz has a contrary opinion to this whole matter. He has measured the craniums of Americans from the colonial days until the late 20th century and the data has shown that our brain volume is getting larger. He thinks this has to do with the availability of nutrition, and that it has become more abundant over that period of time.
When famine and starvation was commonplace in societies, a large brain would have made that person have a higher chance of dying. Since Americans have not had to worry about that for at least 200 years, a large brain is no longer a problem and started to reverse the downward trend.
PERSONAL OPINION
I find it hard to believe that the trend of smaller brains has been reversed. According to this 2013 study, reaction times and IQ have decreased in Westerners since the Victorian age.
The data shows from 1889 until 2004 the average IQ has decreased by 1.16 points per decade, resulting in a total loss of 13.35 points. If that trend has continued, we are now down by 15 points, which is one standard deviation.
Reaction times have also decreased from 194 milliseconds down to 275. This test is a simple measurement between seeing a visual stimulus and pressing a button. It is useful to gauge a person’s mental processing speed, and is considered an indication of their general intelligence.
I believe that the main reason the human race is becoming less intelligent is the idiocracy theory, but the other theories are helping it along too.
We have coddled the stupid and worthless in ever increasing amounts, even to the point where they receive more government money for having more children. In the beginning of the movie Idiocracy, it shows a man with a low IQ having dozens of kids while the intelligent people end up having none. It is known that IQ is highly influenced by genetic factors.
Also by increasing the safety of everything the dumb mistakes that have cleaned up our gene pool in the past have been lessened. Improved medical technology has saved those that managed to bypass the safety features. These Darwin awards are a necessary and useful tool that needs to happen.
I know some of you will want me to mention technology. Starting ages ago with writing, technology has slowly reduced our need to memorize things, and within the past 20 years or so our need to memorize anything has quickly dissipated. We no longer need to know directions, facts, or phone numbers thanks to technology and the internet. It seems to me that eventually some people will integrate technology into themselves. It will be interesting to see what affect that has upon the brain in future generations.
I hope that I am wrong and our brains are just becoming more complex, more of the folds that massively enhance the connections between different neurons. After all, Einstein’s brain was not any larger than normal, but he had a fourth ridge (normal people have three) in his mid-frontal lobe.
It might not be the size that matters, but how you use it.
Leave a comment with what you believe is happening to our brains.
Sources:
- If Modern Humans Are So Smart, Why Are Our Brains Shrinking?
- Our Brains Are Shrinking. Are We Getting Dumber?
- People Getting Dumber? Human Intelligence Has Declined Since Victorian Era, Research Suggests
- Are brains shrinking to make us smarter?
- We're all getting smaller and our brains are shrinking... is farming to blame?
- Pictures: 1 2 3 4 5 6 7
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@getonthetrain
I love this post.
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Thanks!
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Smaller, Lighter, Thinner, we are the computers of the past! In the future we will just outsource the shrunken part of the brain and go wireless!
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It does seem like the most likely path that many will take! We have always used technology to diminish our weaknesses and enhance our strengths. The technology do so so in our brains is in its infancy, but will soon be developed into something that will be available to those that want it. Thanks for the comment :D
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Interesting thread! I'm actually familiar with almost all of the research you mentioned.. And I was getting ready to respond about Einstein and then at the very end noticed you covered that as well.
I wouldn't necessarily say brain size is what's more important, but the connections and how the brain is wired together and.. Look at computers, they keep getting smaller and smaller, maybe if evolution happened as decribed by many, the shrinking of the brain might also been an evolution, like.. It's figuring out how to do more with less per se.
Who knows though.. I think the Idiocracy theory is a good theory, though.. You could have a big brain and still be really stupid and you can have a smaller brain and be super smart.. So.. I don't necessarily think size is as crucial as many seem to make it seem to be.
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There is definitely the possibility of our brain connections getting better. The problem lies in that we don't have any actual brains from people 10 or 20,000 years ago to study and compare ours with. So we will not know that for sure.
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Lemme ask you a question. If we don't have brains from that far back, how do we know they are shrinking so much from so far back?
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Hey @getonthetrain.
Scary what out heads may look like in a few hundred years, lol! Great post.
Currently at the Steemfest and having a fantastic time. Always checking for your new posts after the day is done, buddy. Excellent job as alwasy, bro!
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Glad you are having a great time over there. I would probably be there too if I wasn't stuck in the middle of the desert for a 6 month tour. :)
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herd animals don't need a lot of agressiveness. pack animals do. I wonder if there are studies contrasting the relative brain sizes.
Are humans pack animals, or herd animals?
Of the other reasons you have listed as possible factors, I like the Idiocracy take the most. We no longer say, "well let's leave Slow Joe to that bear chasing us". Then Slow Joe has kids and now we're all a little slower.
Finally, I would expect that almost all of these factors come into play at some level of contribution.
And to tell you the truth, survival of the species doesn't depend on IQ either, Whether we are pack animals or herd animals, it is the social organization of humans that lets us survive. Sure, the guys with outlier IQs advance the human race, but it's the people getting laid that perpetuate the race.
I hope this following link advances your discussion!
Why are people so stupid????? Honestly, why?
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It is definitely a complex issue, and I suspect that the different theories all have some play in it like you say. If people today are any indication, a high IQ often means that procreation is lower compared to an average or below IQ individual.
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Joe Rogan did a hilarious bit on dumb people having kids. I wish I could find that clip
The introduction to the movie Idiocracy is also pretty good.
But we are missing a trick in linking breeding to IQ. It is going to be the more aggressive males that procreate most successfully.
Kind of brings us full circle
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I think it's partly due to we are using our brain less and depend more and more on technology from calculator to smart phones, etc.
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I can't be convinced that technology has played that large of a role, this has been happening for 20,000 years or so. It is easy to look around at everyone on their smart phones and see the effects of it today, but it hasn't even been one generation with this level of daily technological laziness.
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Another theory. Because we are creatures of habits. So, resistance to change that we rather keep doing the same thing without thinking.
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I agree with you: the user is the problem, not the material :)
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Shared on twitter
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Great! Thanks!
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Disclaimer: I am just a bot trying to be helpful.
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The size isn't important, a T-rex had a huge brain but in relation to it's mass it's brain was tiny. The ratio of the brain size to the body mass (minus fat cells) is what's key - otherwise tall men would always be more intelligent than small men and being overweight would make people incredibly stupid. So height for height a man has heavier bones than a woman so he needs a larger head. Similarly, people with angular leg bones have less mass, height for height, than people with rounder bones, but they have longer legs, a narrower pelvis, a shorter spine, a longer neck and a smaller head.
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If our bodies shrank as fast as our brains have been doing in the last 20,000 we would have to be the size of pygmies to still have the same ratio of proportional scaling.
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Lol. Really? How big were people 20,000 years ago?
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It is not a 1-1 ratio. It takes a large amount of the brain just to control all the 'background programs' needed to live. Once you have that complete, you can add mass but the brain doesn't have to grow as much. If someone is 10% bigger, the brain will only need to become a small percentage larger to control that extra mass, nowhere near 10%. So that 10% of our brain that we lost equals us being pygmy sized.
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Yes, I was wondering if we are pigmy sized compared to people 20k years ago.
Also, maybe the slower reactions are simply due to toxoplasmosis.
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The average I.Q in the 70s in the UK was 107 now it's 100.
Scientists believe that the main factor in I.Q is genetics, but I think that their tests are deeply flawed. The main flaws are that they assume that everyone who takes tests are trying their best and similarly, that everyone is at their optimum when they take a test.
In the 40s Aboriginals came out with an average I.Q of 70, which means over there I.Q 100 makes you a genius! I just don't believe it- I think they just couldn't see the point of the test cos they had stuff to be getting on with. I.Q 100 wouldn't even be capable of inventing the wheel!
I think kids these days lack concentration, they are over indulged and they simply can't be bothered trying.
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Aboriginals have consistently scored the lowest average IQ when tested and they have been tested numerous times spanning decades. The second lowest? Pygmy peoples.
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Maybe they are consistent about not giving a shit about dumb tests.
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