metro: 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 s3xes,’ 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.
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.
Source: Published by metro