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People like to think there is a positive correlation between brain size and cognitive function. That is to say, the bigger the brain the more powerful it will be.
This belief perhaps stems from an understanding that a bigger brain has more neurons, and therefore can operate with higher power and function.
According to recent discoveries, however, it seems that is not the case. Emerging research has prompted scientists to question their understanding of the brain.
For example, some research shows that a higher level of gray matter—the outer layer of the brain—makes for a higher IQ.
This has left researchers puzzled, since it was around this time that huge technological progress was made. For the first time, humans walked around and formed complex civilizations.
Researchers have come up with a number of hypotheses to explain why the size of the average human brain has dwindled over the course of these three millennia.
The first hypothesis is based, somewhat surprisingly, on what we know about the brains of ants. Despite the obvious difference in size, the brains of some species of ant are strikingly similar to ours.
In fact, some ant species even practice a form of agriculture, which involves their growing and harvesting huge amounts of fungus inside their nests.
The anthropologists from Dartmouth studied the brain size of a number of ant species and found that those in large societies had bigger brains, unless they also had the agricultural ability.
This suggests, in turn, that more complex social systems might cause ant brains to shrink, perhaps because there is a greater division of labor and cognitive capabilities are divided.
This discovery prompted the researchers to question whether the same thing happened in humans; whether at some point we began to share and externalize information in the brains of others.
Of course, there are huge differences between human and ant brains, so any parallels between the two should be drawn with great caution.
Another hypothesis for why the human brain has shrunk is related to the emergence of writing. We began putting pen to paper around 5,000 years ago, two millennia before the shrinkage.
Researchers have questioned whether the emergence of the possibility to put thoughts down on paper, and therefore externalize them, could have had an impact on brain volume.
There are other theories out there, but these are quickly discredited if we accept that the shrinkage only began as recently as 1000 BCE.
For example, it was thought for a while that domestication might have caused our brains to get smaller. We see this in many other species, after all.
For now, the question as to why our brains are smaller than our ancestors remain unanswered. But there is another important question to consider: does bigger actually mean better?
The reality is, however, that a bigger brain doesn’t really make for a smarter person, unless the conversation is about tiny differences across a vast population.
As described earlier, we often correlate brain size with brain power. We like to think that people with bigger brains are somehow smarter.
In 2018, a team of researchers studied the brain size and IQ of 13,600 people. It found, on average, that those participants with bigger brains did slightly better on IQ tests.
Crucially, however, the relationship was non-deterministic. Some participants scored very high on the IQ test despite having a smaller brain, and vice versa.
It might also be the case that other structural features have a material impact on a person’s intelligence.
There is still a huge amount we don’t know about the brain, but the general consensus is that structural differences are more likely to impact intelligence than sheer size.
We know that the brain has shrunk to its current size over the last 3,000 years. But will it continue to shrink, and what does that mean for our species?
Sources: (BBC)
See also: Are you left-brained or right-brained?
It is pretty common knowledge that the brain is a complex organ. Responsible for pretty much everything our bodies do, the human brain is powerful and elusive.
Most people think that having a bigger brain must equate to higher brain function. By that logic, the 21st-century human brain should be larger than the brain of centuries and millennia gone by. Emerging research suggests, however, that our brains have actually shrunk over the last 3,000 years. This discovery is keeping researchers busy as they look to understand why our brains are getting smaller.
Intrigued? Check out this gallery to learn all about the human brain and why it might have shrunk.
Why the human brain has shrunk
And some analysis of whether it matters
LIFESTYLE Curious
It is pretty common knowledge that the brain is a complex organ. Responsible for pretty much everything our bodies do, the human brain is powerful and elusive.
Most people think that having a bigger brain must equate to higher brain function. By that logic, the 21st-century human brain should be larger than the brain of centuries and millennia gone by. Emerging research suggests, however, that our brains have actually shrunk over the last 3,000 years. This discovery is keeping researchers busy as they look to understand why our brains are getting smaller.
Intrigued? Check out this gallery to learn all about the human brain and why it might have shrunk.