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Shrinking Brain in Humans

Scientists are alarmed by shrinking of the human brain

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A study published earlier this year confirmed what scientists have long believed to be the case – the human brain is shrinking.  For more than 7 million years the hominid brain has grown increasingly bigger, almost tripling in size.  But for the last 10,000 years, the human brain has been shrinking at an alarming rate and no one really knows why. New research has attempted to answer this question by examining size changes in specific regions of the brain.

The study published in the American Journal of Physical Anthropology was carried out by a team of Chinese researchers who looked at over 500 endocasts from the past 7,000 years. Endocasts are moulds of brains created from the imprints on the inside of the skull. They are an invaluable resource when studying human evolution, allowing us to track how our brain has evolved over the past few million years.  The results confirmed what has long been suspected – our brains are getting smaller.

 

It was in 2010 when researching a skull that belonged to a Cro Magnon man that scientists first discovered the brain of our ancient ancestor was significantly larger than humans today. This has been replicated time and again and it can now be said that the human brain has decreased from 1,500 cubic centimetres (cc) to 1,350cc, irrespective of gender and race.  If we continue on this path, we will end up having the same-sized brain as Homo Erectus, an ancient human species which had a brain of 1,100 cc.

Does a smaller brain mean less intelligence?

Scientists have been debating for many years about whether a smaller brain means less intelligence, and no agreement has been reached.  To clarify, it is not simply the size of the brain that is relevant here, but the size of the brain in relation to body size, referred to as the Encephalization Quotient (EQ).  Research has found a close relationship between intelligence and EQ. 

Over millions of years, the hominid body has been shrinking but the worrying fact is that our brains are shrinking faster than our bodies. Does this mean human beings are getting dumber, or are smaller brains not necessarily bad?

The human brain is shrinking faster than the shrinkage of the body

The human brain is shrinking faster than the shrinkage of the body. Image credit: Superscholar.org

Many scientists have argued that bigger doesn’t always mean better.  Duke University anthropologist Brian Hare says "the decrease in brain size is actually an evolutionary advantage" because it could indicate we're evolving into a less aggressive animal. For example, the common chimpanzees have bigger brains than bonobos, but they are less likely to resolve issues through teamwork because they're more aggressive. 

Other proponents of the ‘bigger isn’t better’ hypothesis have argued that our ancestors had a larger visual cortex because good vision was necessary for survival. But as social support increased, vision became less important. Those with smaller visual cortexes had more resources available for social regions of the brain, thus increasing chances of survival.

However, the findings of the new study conducted in China are not consistent with these theories because the results indicated that it was not one particular area of the brain that was shrinking – the whole brain has been getting smaller. If the hypothesis about the visual cortex was correct, we should see shrinkage only in that region of the brain.

The one exception is the frontal lobe, which actually seems to be increasing in size. The frontal lobe is the region of the brain responsible for speaking, comprehending the speech of others, reading and writing. It is possible that we are doing a lot more of that now – at least the reading and writing part – compared to our ancient past.

While plenty of hypotheses have been put forward to justify the shrinking of the human brain, there remain many who are less optimistic. The authors of a study published in 2012 maintained that humans lost the evolutionary pressure to be smart once they formed agricultural settlements. 

"A hunter-gatherer who did not correctly conceive a solution to providing food or shelter probably died, along with his/her progeny, whereas a modern Wall Street executive that made a similar conceptual mistake would receive a substantial bonus and be a more attractive mate. Clearly, extreme selection is a thing of the past," the researchers wrote in the journal article published in the journal Trends in Genetics.

More than 4,000 years ago, great civilizations existed around the world and the ancient inhabitants built incredible buildings and cities with great precision and beauty, often with astronomical alignments that we are only just beginning to realise. Nowadays, technology has taken over, rendering our need to apply skill, creativity, and memory virtually redundant. Instead of memorising navigational routes we switch on our ‘sat navs’ and rather than storing phone numbers and addresses in our memory banks, we have them all to hand on our iPhones and Blackberries.  Our technology is evolving rapidly, but sadly it seems that we are not.

By April Holloway

Comments

The human brain has great potential, but if we keep being fed rubbish, we will eventually loose whatever potential we have.you not lose potential from fed brain rubbish but you brain with age need more time to rewire. So you will need more time to increase your brain efficiency but dont lose this ability to change except childrens due to brain growth(development wrong stimulation can alter brain growth in some regions).

I agree with you our brain is very plastic there are even few case where people have 70% damage from stroke and their brain reorganize and create connection which allow them function normally. What expierience you give brain so you will had a brain. "Film, Television" I will say that contents cause effect there can be highly stimulating programs on tv and I see recently study which shows some benefits to brain from wathing tv. But also dumg programs can be beneficial because our brains must sometimes rest and with little stimulated programs have good opportunity(there are some studies showing correlation with overworking brain and neurodegenerative diseases) We can conclude that average people are less inteligent but this is due to increased borns in families with lower inteligence. Many video games gets attention among rehabilitants. SO as I say contents not device cause stimulation to brain and this organs can adapt to virtualy all situation.

The powers that be are shrinking our brains by giving it less to feed on.  Film, Television, and the rubbish we are fed, tend to dumb us down, and it is working well.  

The human brain has great potential, but if we keep being fed rubbish, we will eventually loose whatever potential we have.

We are not even capable of making good decisitons about our earth.  Instead, we are fed rubbish.

It is time to take back control again, and use our brains in more demanding areas.

Glee

johnblack's picture

Very good points :-)

P.S about We use glasses instead of exercizing our eyes" many refractive errors are due to shape of cornea not muscle only some of them are from using near subject but only small % of all refractive errors. that why you exercise cant do anything and glasses dont cause that your vision will detorate look at studies which research that.

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