Cro Magnon skull shows that our brains have shrunk

Mar 15, 2010 by Lisa Zyga weblog
A 3D image of a Cro Magnon brain. Credit: Times Online.

(PhysOrg.com) -- A new replica of an early modern human brain has provided further evidence for the theory that the human brain has been shrinking. The skull belonged to an elderly Cro Magnon man, whose skeleton is called Cro Magnon 1. The entire skeleton was discovered in 1868 in the Cro Magnon cave in Dordogne, France, and has since become one of the most famous Upper Palaeolithic skeletons. Using new technology, researchers have produced a replica of the 28,000-year-old brain and found that it is about 15-20% larger than our brains.

To produce the brain replica, called an endocast, the scientists first digitally scanned the interior of the empty skull. The images revealed the impression left by the brain on the neurocranium, which was then transformed into a 3D image. Software was then used to fabricate the brain endocast.

The researchers, including Antoine Balzeau of the French Museum of Natural History, said that an initial assessment of Cro Magnon 1's skull supported the theory that brains have grown slightly smaller over the past tens of thousands of years, reversing an earlier trend toward larger brains.

The finding doesn’t suggest that humans today are less intelligent than earlier humans. Although previous studies have found a very small relationship between brain size and intelligence, many other factors affect brain intelligence.

For instance, different parts of the brain have different functions. The researchers found that the Cro Magnon brain appears to have had a smaller - the brain region linked to motor control and language - than our brains today. The researchers explain that this finding shows that some parts of the brain are more “compressible” than others, while other regions seem to provide a benefit by growing larger.

Although scientists don’t know for sure why our overall brains are shrinking, some researchers hypothesize that our brains are becoming more efficient as they grow smaller. Having a large comes at a cost, so smaller brains have an advantage since they enable the body to use the extra energy for other purposes. On the other hand, perhaps a large skull had certain advantages for earlier people. One idea is that Cro Magnons needed large skulls because of the difficulty in chewing their food, which included lots of meat such as rabbits, foxes, and horses. Since our food has become easier to eat, we don’t need such large skulls or jaws. Another theory is that the high infant mortality rate in earlier times meant that young humans had to be physically robust (with large heads) to survive their early years.

The researchers plan to show a mold of the later this week at the National Museum of Natural History in Washington, DC.

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More information: via: Times Online

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User comments : 38

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HeloMenelo
1.4 / 5 (5) Mar 15, 2010
Kinda like processors becoming smaller and more efficient, if smaller means more intelligence i guess Killer whales are more intelligent than humans. :)
Husky
3 / 5 (4) Mar 15, 2010
I probably got to stop watching soap television, before my brains shrinks to peanut size
finitesolutions
1 / 5 (5) Mar 15, 2010
I have a big brain but i only use like 2%. The rest is idle.
Shootist
1.4 / 5 (5) Mar 15, 2010
That cro-magnon had a larger brain-case isn't exactly news. see "The Naked Ape" copyright 1967.
Glyndwr
5 / 5 (2) Mar 15, 2010
But what is the sample size of Cro magnon studies? People today have varying brain sizes lol ...i hope they not assuming brain changes from a few skeletons
tpb
5 / 5 (2) Mar 15, 2010
I sure hope that this conclusion isn't based on only one skull.
Skull sizes vary considerably from person to person.
Thrasymachus
4 / 5 (4) Mar 15, 2010
Funny, I use almost all my brain. Granted, I only use between 2 and 10% at any given time, but then, if all my brain was active all at once, I'd be lying on the floor seizing, drooling, and probably dying.
Loodt
1.1 / 5 (10) Mar 15, 2010
brains have grown slightly smaller over the past tens of thousands of years...ever since they lit that first fire.

We are only just beginning to understand the pernicious long-term effect of over exposure to CO2!
OregonWind
1 / 5 (1) Mar 15, 2010
So much for the futuristic movies showing, in the next step of our evolution, people with huge brains.

However, I have to agree with some of the commentators here, the fossil samples are quite few and the human brain does varies, in size, from people to people.

deatopmg
1.8 / 5 (5) Mar 15, 2010
Glyndwr is correct! This is a sample of 1.
how many std dev's is 10-20% larger than today's norm?
Caliban
3.7 / 5 (6) Mar 15, 2010
Important to remember, though, that these people didn't have writing, books, computers, tools, mechanisms, et c. and all the things that modern humans can utilise as off-board memory. They had to carry around with them, in their heads, everything they knew about themselves and the world, including their culture, information about food, weather, geography, technology, history- their entire world. Probably required a bit more of a brain to do that.
OregonWind
1 / 5 (2) Mar 15, 2010
Caliban

However, are we not required to learn how to read those books we carry, to remember what we read, to learn how to use all the tools we have, to use computers, mathematics, smart phone, driving, piloting, printers, fax machine, etc, etc?

I bet that average modern human carries far more information in the brain that the average guy 28000 years ago.
Caliban
1 / 5 (2) Mar 15, 2010
OW,

While it's true that we possess a lot of devices, et c. that we have to know how to use, a lot , if not most, aren't essential to survival. I understand that you mean that just the knowledge necessary to make use of these things is probably sufficient to offset any difference, but let's just say that I remain uncertain. I think that there is a difference between essential and nonessential relative to ensuring the survival of both yourself and the larger community.
PinkElephant
5 / 5 (1) Mar 15, 2010
I think Caliban has a point, or at least a good fraction of one.

Aside from no externalization of knowledge, ancient humans also lived in smaller tribes, and so had to be more versatile: they couldn't afford to specialize like modern humans do. E.g. I have no idea how to make my own clothes, how to hunt down and prepare my own meal from scratch, make my own tools and weapons, treat my own diseases and injuries, etc. Put out alone into the wild, most modern humans would be dead within weeks...

As to what might be driving us toward smaller brains: how about the narrow(ing?) human birth canal? Obviously, babies with smaller heads have a better chance of surviving birth, and a smaller chance of killing their mothers in the process. I think it's telling that ancient "earth mother" figurines show women with exaggerated pelvises: a universal ancient attribute of female beauty. The prevailing modern ideal of women is closer to that of boys, with hips being the narrower, the better...
PinkElephant
not rated yet Mar 15, 2010
Here's another potential reason for shrinking brains in modern humans: smaller brains are faster. Couple that with the observation, stated in the article, that the larger brain was accompanied by a smaller cerebellum, and what do you have?

Slower reactions, coupled with less refined coordination, would create a disadvantage in battle. As human population densities escalated, war would have become increasingly common and frequent, selecting the quick and the agile, over the ostensibly just clever.

And here's yet another possibility: diet. Maybe the Cro Magnons ate a lot more meat and fat (building blocks for brain matter), while more modern humans eat mostly grains and vegetables (sufficient for overall body maintenance, but not so great for brain construction.) Perhaps part of the blame goes to agriculture (and attendant periodic famines) and in general the maturation environment, rather than genetics. Check this out:

http://en.wikiped...sumption
HealingMindN
not rated yet Mar 15, 2010
It's possible that cro magnon was more well rounded than hominus erectus because they had to know the habits of prey, predator, and the hunt. They were just plain different. Bigger is not necessarily better. It's what you do with it is what counts.
Caliban
1 / 5 (2) Mar 15, 2010
Can't make out for sure if they are saying that CM's cerebellum was smaller in proportion to total brain mass, or if they mean that it was smaller than the cerebellum of a Modern Human.
Hard to say what that might correlate to. Perhaps their's was more efficient? Less? At any rate, I rate it as highly doubtful that they were less well-coordinated than moderns.
Recovering_Human
not rated yet Mar 15, 2010
How does having a larger head correlate with being more physically robust?
DaveMart
not rated yet Mar 16, 2010
It would be interesting to know which bits of the Cro-Magnon brain were larger than ours, as well as which were smaller.
The grater 'compressability' theory does not seem to me to be the least hypothesis - perhaps we are just better now at language and motor skills.
superhuman
not rated yet Mar 16, 2010
I bet that average modern human carries far more information in the brain that the average guy 28000 years ago.


Information is stored in neurons so unless you believe they had larger brain but fewer neurons which seems unlikely they stored a comparable amount of information.

The main difference is the type of information stored, we don't have to worry about many things that used to occupy our ancestors - how to acquire enough food in the wild depending on the season, how to prepare it for eating, where to find water, how to avoid predators, parasites and diseases, which plants are safe and useful, how to produce tools and clothes, how to build shelters, and how to pass all that knowledge to ones offspring.
ontheinternets
not rated yet Mar 16, 2010
It's good to keep gathering evidence, but I figure I should comment that this isn't entirely new -- it's just more evidence. My anthropology prof mentioned this about Cro Magnons more than 10 years ago.. and she didn't say/do anything to give the impression that she thought it was in question.
marjon
1 / 5 (1) Mar 16, 2010
It would be interesting to compare the brains of those who have well developed natural senses like sight, smell, hearing with CroMags.
ontheinternets
not rated yet Mar 16, 2010
After adding my comment, I noticed Shootist's comment. Whoops. Anyway, consider my comment to be in support of his. While I'm at it, I meant to say that perhaps the measurement of the cerebellum is something new at least (the headline may be an attempt at a sensational take on the research, while the researchers were doing something different).
OregonWind
1 / 5 (2) Mar 16, 2010
I am not sure that today we are using our brains in a slower way, actually I doubt it. What about driving or working with computers or playing games? Wouldn't that require a faster brains?

I don't think that the survival instinct had decreased its intensity in the last 28000 years. I think that we have the same needs just in a more complex world. Today's environment should favor a bigger brain. for information storage or faster ones for processing it.

The social and intellectual complexity of the world today is a much bigger challenge to our survival instinct and require us more sophisticated response and adjustment.

The reason our brain is shrinking is not very clear at this point. However, the idea that we changed our diet in the last thousands of years could be a reasonable hypothesis to be considered.
marjon
1 / 5 (1) Mar 16, 2010
The reason our brain is shrinking is not very clear at this point. However, the idea that we changed our diet in the last thousands of years could be a reasonable hypothesis to be considered.

Switching from high protein, high fat diet to grain based diet may be the answer. Certain high fat (specific type) diets help epileptics.
http://www.epilep...nic.html
This was CroMags diet.
OregonWind
1 / 5 (1) Mar 16, 2010
marjon

That hypothesis could be tested in today's world if we find isolated populations living with different diet. A possible candidate would be the natives in the deep Amazon forest. The anthropologists could compare the natives in the deep Amazon ( never affected by today's diet) with the people living in the cities. The natives are hunting and gathering probably (emphasis here) in the same way that did the Cro-Magnons. Are their brains bigger in average or the same size?
OregonWind
1 / 5 (2) Mar 16, 2010
The Amazon natives will also test the above ideas that hunting and gathering food like the Cro-Magnon would keep the brain larger. Even with the Europeans invasion, their living style, diet and culture had not changed much or almost nothing. They are pretty much isolated for thousands of years.

Now if we detect that even the deep Amazon natives also have their brains in the process of going smaller then we would need some other ideas.
Jimee
not rated yet Mar 16, 2010
There is a good article in Scientific American on the changing views concerning brain activity and what constitutes the active level of our consciousness. That 10% may very well be passe.
dsl5000
not rated yet Mar 17, 2010
I could believe that our brains are shrinking...but that is the case with premature babies being born daily, drug abuse far more frequent and wide spread due to advanced factories and cultivation methods.

In addition, we are less active physically. When was the last time you had to go out hunting or gathering to put food on the table (Going hunting at a supermarket and gathering food from aisle 4 doesn't count)?

All that information...a lot of it has become garbled. E.g. Masturbation leads to hairy palms...and blindness.

lol...it's ok to think we are smarter now :) How many jack-of-all-trades are out there? Probably very few. Most of us specialize in a specific field but are clueless in others. It doesn't mean we are stupid...but being smart can be relative :P
dsl5000
not rated yet Mar 17, 2010
following up from my previous statement. It could be that modern Humans are better at warfare, especially if our cerebellum is more extensively developed. Archery, melee combat that requires extensive know-how of balance, etc.

Perhaps in the end, we're just that good at killing stuff. A.k.a. we are the top dogs and the cro-magnons came out as dead dogs :O

Smart at killing and warfare. E.g., a Scientist vs. a Navy seal. Both are intelligent, both specialize in different fields.

Of course, inter-species off-spring is a possibility...we have inter-racial off-spring so...giggidy giggidy, alright! :P
Nyloc
not rated yet Mar 20, 2010
The question is, what was the Cro Magnon's "relative brain size"? Every time I hear references to cetaceans, I hear that though their brains are larger, their brain size relative to their body size is what matters. Even among modern humans, not all our brains are the same size.

If modern humans do have smaller relative brains, it must be due to evolutionary pressure. Agriculture produced surpluses, which gave us the resources to wage war. Medicine saved many who wouldn't have survived birth. Evolution does not favour intelligence, just survival.
breadhead
1 / 5 (1) Mar 21, 2010
You say 28,000 years old, I say no more than 4,400. So what? People today have different sized heads. If this to you is an example of evolution, it is more of, "De-volution". Something (Size) is being lost. You compare the human brain to microprocessor silicon size reductions, and speed increases? Give me a break.
Slotin
1 / 5 (1) Mar 21, 2010
Boskop Man is a type of hominid based on a skull discovered in 1913 in South Africa whose existence and interpretation is controversial. Originally, the skull was claimed to be 30 percent larger than that of modern humans and they were taken to have lived in southern Africa between 30,000 and 10,000 years ago.

http://en.wikiped...skop_Man
Paradox
not rated yet Mar 22, 2010
Perhaps in the end, we're just that good at killing stuff. A.k.a. we are the top dogs and the cro-magnons came out as dead dogs :O


We ARE the Cro-Magnon. They didn't die off, as they are us.
Their brains were about the same size as ours. Some were larger, some smaller, but they averaged out about the same. One specimen says absolutely nothing against the many other skulls that have been found.
The Neanderthals however, had a somewhat larger brain than we do.


That hypothesis could be tested in today's world if we find isolated populations living with different diet. A possible candidate would be the natives in the deep Amazon forest. Are their brains bigger in average or the same size?


If you were to look at some isolated tribe, you would find that again, their brains are about the same as ours.
You can Google all of this, and get more reliable info then you will get here.
jgelt
not rated yet Mar 22, 2010
The limit on how small might be a matter of wattage.
Improved circulation alone could be responsible for allowing a brain of equal or greater wattage to be contained in a smaller cranium. That's just a hypothetical explanation for which I know of no evidence, but there could be reasons that have nothing to do with intellect.
breadhead
1 / 5 (1) Mar 22, 2010
Everything mentioned in the article are guesses at best. How do "Guesses" fit with the scientific method? In the end we are left still with guesses. I can therefore be just as "scientific" by saying these skulls are from people within the biblical timeframe of 4400 years or so.
Glyndwr
5 / 5 (1) Apr 01, 2010
Margin of error anyone? ;) Interesting but lets find more Cro magnon skulls first. Best wishes :)
DonR
not rated yet Apr 02, 2010
Assuming brain capacity/intelligence or whatever being equal across Cro-Magnon and Homo Sapiens, it's not surprising heads are smaller, considering the birthing method we use.

Those with slightly smaller heads would have been easier to birth, meaning less complications and a lower mortality rate for both baby and mother.

Also, to those people sobbing about this being a single skull and the sample size being small, go back and read the VERY FIRST SENTENCE and note the use of the word "further".