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Why Humans Are Getting Dumber: Our Brains Are Shrinking!

Got a crotchety old guy who kept telling you that youngsters today are getting dumber by the minute (right before he told you to get off his lawn)?

Well, he may be onto something: scientists discovered that our brains are actually shrinking!

The downsizing of human brains is an evolutionary fact that took science writer Kathleen McAuliffe by surprise.

"I said, 'What? I thought it was getting bigger!'" she tells NPR's Jacki Lyden. That was the story up to 20,000 years ago, she learned. Then, the brains of our ancestors reversed course and started getting smaller — and they've been shrinking ever since.

Cro-Magnon man, who lived in Europe 20,000 to 30,000 years ago, had the biggest brains of any human species. In comparison, today's human brain is about 10 percent smaller. It's a chunk of brain matter "roughly equivalent to a tennis ball in size," McAuliffe says.

The experts aren't sure about the implications of this evolutionary trend. Some think it might be a dumbing-down process. One cognitive scientist, David Geary, argues that as human society grows increasingly complex, individuals don't need to be as intelligent in order to survive and reproduce.

I don't know about the science, but it sure explains Jersey Shore! http://www.npr.org/2011/01/02/132591244/our-brains-are-shrinking-are-we-getting-dumber

Photo: Emergency Inflatable Brain from the NeatoShop


Why does smaller mean dumber? We still know so little about the brain and how it works that couldn't it be that our brains are getting smaller but more complex in its function?

Or did I just prove that we are getting dumber?
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i heard this piece on npr and they were pretty clear about the fact that it doesn't seem to be making us dumber

rather creatures with smaller brains are more likely to work cooperatively and actually succeed in tasks that require more than one person

they pointed to experiments comparing chimpanzees with bonobos (bonobos have smaller brains and more cooperative groups)

while the question of whether or not this cooperative function is akin to intelligence is still debatable, as intelligence in many ways is hard to measure, i would be willing to venture a guess that the people who manage to succeed in a task (civilized humans and bonobos over chimps) are probably the "smarter" ones.
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But the Flynn Effect states that each generation is progressively scoring higher and higher on standardized IQ tests - spatial reasoning seeing the largest jump. If our brains are getting physically smaller, maybe it's a more a matter of "trimming the fat" so to speak.
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I am pretty sure an elephant has a larger brain than I do, and I know elephants are pretty smart as far as beast goes, but I don't think you could teach one differential calculus.

So is brain size really an indication of intelligence.
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Smartness between a chimpanzee and a human is pretty clearly observable. But smartness between two humans is more often difficult to detect. Imagine you are plopped down in the middle of Southern Africa with Albert Einstein at his most productive age. If you encounter a bushman who finds you food, water, and shelter you will be sure to consider him much smarter than Einstein who keeps babbling about God and dice.

Anyway, brain size is probably not a very useful proxy for problem-solving ability. More likely, the size and health of the neo-cortex is a better indicator as it probably correlates to higher number of synaptic connections. Even then, if we discover a correlation between a kind of smartness and brain physiology, I doubt it would be a good measure of how successful, productive, motivated, happy, wise, etc. the person will be. Sometimes a hardship with a good set of mentors and friends produces the best results.
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@Krikkit - the idea is brain size relative to body size. Our brains are (relatively) bigger than elephants' brains. Don't ask me why relative brain/body size is supposed to be important - it's just how the story goes.
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Here's my uneducated theory: our brains might be smaller now because the extra brains we were carrying around were devoted to our sense of smell as that sense would be highly valuable in locating food sources both animal and vegetable in our hunter/gathere past. As we learned how to domesticate animals and grow our own food, a highly developed sense of smell was less necessary and the attending brain matter lessened over the generations.
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If we are to suppose that brain size is correlated with intelligence, then we should be forced to conclude that men are smarter than women, on average.

Furthermore, we would be forced to conclude that Neanderthals were smarter than homo sapiens. Again, a hypothesis that is generally unsupported by the available evidence.

Here's an alternative hypothesis: brain shrinkage is correlated with agricultural development. Maybe our diets have changed to allow for smaller, more efficient brains. After all, there is certainly evolutionary pressure to have smaller, more efficient organs that consume less energy to perform th same tasks.
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"brain shrinkage is correlated with agricultural development." - cwcaton.

I would be curious to know whether the pattern of shrinkage coincided with the development of agriculture as that may play into either or both of our hypotheses.
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