Brane Space: Yes, Evidence Shows Human Brains Have Shrunk 10 Percent In Last 3-5 Millennia. The Question is: Why?

Degree of brain shrinkage in humans over last 3-5,000 yrs.

We have now learned that a growing body of evidence indicates our brains have shrunken in size sometime following the end of the last Ice Age. This, thanks to the research by Jeremy DeSilva and co-authors. According to DeSilva, a professor of paleoanthropology at Dartmouth College, quoted in a WSJ piece (Sept. 9):

“Most people think of brain evolution happening in this linear way. It grows, plateaus and stops. But we’ve lost brain tissue equal to the volume of a lime—it isn’t a tiny little sliver we’re talking about.”

While the precise timing of that post-Ice Age brain shrinkage has remained a mystery until now, DeSilva and his team made a major breakthrough. They used a mixture of fossil and modern specimen data to pinpoint that this loss of gray matter happened between 3,000 to 5,000 years ago, according to research published in June in the journal Frontiers in Ecology and Evolution.

Many anthropologists had initially posited the changes coincided with the advent of agricultural practices around 10,000 years ago, and a global shift away from hunting and gathering. This isn’t surprising and underlies the hypothesis (see e.g. 'The Evolution of Consciousness' by Robert Ornstein) that humans in a hostile, (e.g. Ice Age) environment, needed vastly more wits to survive and hence relied more on their individual brains. These challenges, met and resolved, led to an explosion in the size of the neocortex.

But, the arrival of agriculture- and in a more favorable climate- implied more communal action so depended less on the individual for survival. Thus the more-recent dates from DeSilva’s group point to booming eras for ancient civilizations in North Africa, the Middle East and South America—complex societies that they think may have played a role in the shrinkage.

In effect, human societies got so cooperatively organized in the past 3,000 years that we began relying on what researchers call collective intelligence. James Traniello, a biology professor at Boston University and one of DeSilva’s co-authors put it this way:

“It is the idea that a group of people is smarter than the smartest person in the group. So basically, if you live in a group, you solve problems more rapidly, more efficiently and more accurately than what’s possible for any individual.”

That sounds entirely logical and Traniello even admits he got the "inspiration" from the existing example of ultrasocial” insects such as ants. Ants form highly cooperative societies in which division of labor has favored smaller-brained individuals due to an advanced level of social organization. But I am not sure I'd carry this too far.

More plausible to me is the analogy used by Christof Koch, a neuroscientist at the Allen Institute, a Seattle-based bioscience research nonprofit and Lars Chittka- professor of behavioral and sensory ecology at Queen Mary University of London. That is, our mental circuitry evolved to be more optimized—with improved neural connections in a smaller package. So where once IBM computers - like I used in my original solar research- were the size of a room, they now have thousands of times more capacity and fit in your hand.

Lastly, all these researchers point to increasing use of social media, cell phones, laptops etc. as further impetus for collective intelligence and its optimization. But I am not buying. The fact is that all this tech advance has still kept large swaths of the American public at a dumb level - believing almost anything Trump and the GOP rats burp out of their pieholes. Not to mention, the incessant blabbering of the mainstream media about Joe Biden's age - as if not fully realizing the dangerous threats to our democracy they are unleashing.

So, the jury is definitely still out on whether our shrunken brains are truly "optimized" for function - or access to too much of the wrong "information" is merely paving the way for excess shrinkage via collaborative stupidity.

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