Why Have Our Brains Shrunk?

According to an article1 in the New Scientist in the past 10,000 to 15,000 years the average size of the human brain compared to the human body has shrunk from 3 to 4 per cent. The question is why. One explanation for this shrinkage is that the brain has evolved to make better use of less gray and white matter. Some genetic studies suggest that our brain’s wiring is more efficient than it was in the past. However, another explanation is that this shrinkage is a sign of a slight decline in our cognitive abilities.

David Geary of the University of Missouri-Columbia believes that after complex societies developed, the less intelligent could survive on the backs of their more intelligent peers. Previously, the less intelligent would either have died or failed to mate. It appears that this decline might be continuing. Studies have found that the more intelligent people are, the fewer children they have. Today intellectual and economic success are not linked with larger families.

It is interesting to speculate whether this trend will continue or perhaps even accelerate given the widespread use of technology. Is this technology making us smarter by giving us greater access to computations and to external storage (transactive memory)? Or is it making us dumber due to our increasing reliance on technology? At one time multiplication tables needed to be memorized. Now the use of calculators is widespread. At one time more information needed to be committed to memory. Now it can be looked up.

There is even the suggestion that at some point we might no longer need our biological brains. Ray Kurzweil contends that there will be a singularity in the future when our biological brains are replaced by silicon brains (See the Healthymemory Blog Posts, “Are Our Memories Becoming Too Dependent on Technology,” “Achieving the Max in Technical Transactive Memory,’ and “Brain, Mind, and Body”). These questions are interesting to ponder.

1Robson, D. (2011). A brief history of the brain. New Scientist, 24 September, 40-45.

© Douglas Griffith and healthymemory.wordpress.com, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.

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