Our brains are getting smaller.
They may have shrunk by around 17.4% over the last 20,000 years, research suggests.
And unlike the controversial claim that people are growing ‘horns’ in their skull due to phone use, our shrinking brain problem can’t be blamed on modern technology.
‘There are indications from the fossil record that suggest that our brains have become somewhat smaller in the past 10,000 to 20,000 years,’ Michel A. Hofman, professor of neurobiology at the Netherlands Institute for Neuroscience, tells Metro.co.uk.
This is well before the advent of the smartphone.
Actually, in more recent times, evidence that this shrinkage is continuing has been difficult to find.
‘There’s absolutely no scientific evidence that the modern human brain has been getting smaller during the last centuries,’ Prof Hofman says.
‘Generally, these stories are based on inappropriate datasets and bad statistics.’
This ‘estimate’ is because there aren’t any old brains to look at – just best guesses from endocranial casts, models made of the inside of old skulls.
They give an indication of how brain size, shape and surface has changed over the millennia, but some scientists believe they provide only limited data.
Despite the lack of definitive proof, it’s still a concerning prospect to wrap our shrinking heads around.
Although smaller and smaller phones, laptops and computers might be a sign of progress, losing that all-important grey matter doesn’t sound as appealing.
Why are our brains getting smaller? What does this mean for the future? And does a smaller brain mean we’re becoming less intelligent?
‘It does not mean that we are less intelligent than our fossil ancestors,’ Prof Hofman says.
In fact, Anna Henschel MSc, a final year PhD candidate at the University of Glasgow’s Social Brain In Action Laboratory, tells us that the size of the brain is not a good indicator of IQ at all.
‘The relationship is weakly correlational at best,’ she says.
This is a little confusing because, as we’ve evolved, our brains have become bigger on the whole.
They’ve gradually grown in relation to body size from early primates to hominids to Homo sapiens.
But if a bigger brain always equated to more intelligence, then whales and elephants with brains much larger than ours would be much smarter than humans.
Instead, relative brain size might be more important than absolute brain size in determining factors such as intelligence and behavioural complexity.
But again, that’s not always the case.
We have a relative brain-to-body mass of about 2%, which is bigger than many other mammals.
But the brain of a shrew can be 10% of its entire body mass.
As Prof Hofman reminds us, ‘size isn’t the whole story’ and there is a lot more going on.
‘It’s important to consider the brain’s neural organisation, how it works and how the neural network is organised,’ he says.
‘In that respect, you may compare our brain with a computer: bigger does not necessarily mean more powerful or faster.’
A good example, Prof Hofman tells us, is the difference in brain size between men and women.
‘Although females have a considerably smaller brain than males, there are no differences in intelligence between the sexes,’ he says.
‘It simply turns out that male and female brains are differently organised.’
A smaller brain may not mean a less intelligent brain, but why are our brains changing at all?
There’s no definitive answer. At least not yet.
The structure and organisation of the brain are still some of the great unknowns of biology.
Instead, what makes this topic both frustrating and fascinating is that many scientists and researchers have proposed different theories over the years, linking brain size to all kinds of things, including change in climate, lack of aggression and living in big groups.
‘It’s very likely related to the decline in humans’ average body size during the past 10,000 years,’ Prof Hofman says.
‘This may be a consequence of the changes in climate, diet, predation and food availability since the last Ice Age.’
Brain size often scales to body size because a larger body will need a larger nervous system to make it work.
As our bodies became smaller, so did our brains.
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And our shrinking body size could be related to the warmer conditions on Earth since the last Ice Age.
We know colder climes often favour bigger bodies because they’re better at conserving heat.
Others propose our brains became smaller in response to humans becoming less aggressive, more sociable and more domesticated.
You can imagine that, in the distant past, we’d need different skills in order to help us evade predators and hunt for food.
This rings true with Brian Hare’s survival of the friendliest theory, also known as self-domestication hypothesis, which posits that natural selection has favoured friendly, sociable, less aggressive and helpful humans and our brains have changed as a result.
Numerous studies found this to be the case in animals that live in the wild compared to similar domesticated animals.
The wild ones, like wolves, tend to have larger brains and are better at existing without the help of humans.
Smaller-brained animals, like dogs, perform higher on tests regarding social intelligence and have learned to live alongside humans.
Next up there’s what some scientists call idiocracy theory.
This refers to the 2006 film about a man who hibernates, wakes up 500 years later and finds everyone to be way less intelligent than they were.
Cognitive scientist David Geary, of the University of Missouri, and colleagues argued that, as society became more complex, brains became smaller because people needed to be less intelligent to survive and could rely on others for help.
Could our brains be smaller because we’re just, well, dumber than our ancestors?
That depends on your definition of dumb.
Just like the domestication theory, our environments, lifestyles and priorities have changed, so our brains have too.
One 2014 study suggests there could be a correlation with cultural development.
Because much of our memory and cultural information is now stored externally, in stories, art or books, this has altered our brain significantly.
This would suggest that our brains aren’t becoming smaller and dumber but, like your latest smartphone, smaller and more efficient.
Many scientists have suggested it makes sense for our brains would get smaller.
After all, the cost of producing and maintaining a brain is high – it takes a lot of energy to keep one working.
One 2005 study proposes that brain size should be reduced through natural selection whenever the costs outweigh the benefits.
Another study suggested that, although some large animals have greater numbers of neurons in their brains, there might be a lower density of neural activity at any one time.
A smaller brain could mean less overall neurons but more active neurons working simultaneously.
In short, scientists are rushing to find answers and theorise the reasons behind it but there are no clear answers yet.
But maybe none of this matters because we’ll soon develop tech to fill the gaps.
The ability to enhance our brains used to be a mainstay of science-fiction.
Now a number of companies are working on ways to stimulate, enhance and augment our brains with the help of tech.
The most recent example is entrepreneur Elon Musk’s Neuralink.
Musk claims that the company can implant small devices into our brains, which will allow us to better interact with the tech around us.
But it’s still early days.
‘The effectiveness of these devices has recently been called into question in the scientific community,’ Henschel says.
‘Increasing the activity in one brain area might take away activity in another brain area.
‘The different parts of the brain don’t function in isolation.’
This is because of the stability required by living systems to function, known as homeostasis.
This means temperature, salt levels, blood sugar and many more functions are kept balanced by the brain and any external influences are quickly addressed to maintain it.
The reason this subject is interesting and confusing in equal measure is the same reason we don’t know exactly why our brains are shrinking or why experts believe tinkering with our brains with the help of tech might be risky: there’s still so much we don’t know about our own brains.
Maybe a different approach is needed entirely.
Prof Hofman believes the greatest potential lies in our collective abilities.
‘We don’t have to worry in the future about our cognitive faculties,’ he tells us.
‘The 7.5 billion human brains on this planet are forming one huge, highly integrated superbrain with a processing information capacity far beyond that of a single human brain.’
He believes that by viewing brains as part of a larger network in this way we can imagine a whole that’s bigger, smarter and different.
We can see this in the way information about a new discovery or technological achievement can be transmitted to everyone so quickly.
‘We are like an ant colony,’ he says. ‘One ant, on its own, is pretty dumb.
‘But together they know how to form colonies that work with remarkable efficiency and intelligence.’
It’s normal to hear that our brains are shrinking and assume that means something has gone horribly wrong. But the reality is much more complex than that.
There’s no better or worse here, smarter or dumber.
Like our bodies, our lifestyles and our environments our brains may have adapted to better serve us too.
Only when the biggest brains of the science community figure out exactly how the brain works will we get clearer answers.
The Future Of Everything
This piece is part of Metro.co.uk’s series The Future Of Everything.
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