The human (Homo sapien sapien) brain has been shrinking! Don’t get to alarmed however as it’s been shrinking, reportedly, since the Stone Age! In fact, since the Stone Age there have been many changes in our skeletal features and brains. Now you likely think or have been taught that our brains have been consistently getting bigger over the course of human evolution but that, in fact, is NOT true at all. It WAS true for over 2 million years but there is now a reversal going on. Soooo….are we devolving instead of evolving? Or to put it another way…..without new genes being introduced in our species (breed) are we reverting backwards?
According to Dr John Hawks of the University of Wisconsin-Madison over the past 20,000 years our average brain volume has decreased from 1500 cc (cubic centimeters) to 1350 cc. That a reduction about the size of a tennis ball when in terms of our brain is significant. And it’s just not in one location or environment that we find this phenomena as it is found happening all over the world.
If our brains continue to shrink at this rate then 20,000 years from now they will be the size of Homo erectus who had a brain volume average of about 1100 cc. So are we getting dumber or what? Does brain size really matter that much? Or is it how the brain is “wired” that is more important?
There are many theories floating around attempting to explain our shrinking brain volume. Some theorize that humans are, in fact, getting dumber as the gray matter in our brains disappears. Others theorize it’s not about size but about how the modern human brain is wired. They hold the view that our brain wiring is becoming more efficient making us quicker and more agile thinkers so we don’t need big brain volume anymore. Other researchers argue that our shrinking brain is proof positive that we’ve “tamed” ourselves much like domesticated dogs or cows who have smaller brains than their wild ancestors! Dr Chris Stringer of the Natural History Museum in London and a prominent Paleoanthropologists says science hasn’t given this matter enough attention and many simply ignore it as some sort of insignificant detail in modern humans.
Stringer has pointed out something interesting even though I disagree with him much of the time. That is, the more meat we have on our bones, the more brain we need to control massive muscle blocks. It’s called “scaling.” This is one reason Neanderthals had such big brains (averaged 1600 cc). In fact, the Neanderthals had bigger brains that we modern humans yet we portray them as club carrying ignorant brutes! Does it not follow that if brain size matters since they had bigger brains that we do that they were smarter than our modern human ancestors?
20 kya to 30 kya early modern humans (Cro-mags) had the biggest brains in Europe. Again, if larger brains mean more intelligence then that means Cro-mags and Neanderthals were more intelligent that modern humans!
Frankly, we DON’T KNOW why the modern human brain is shrinking but I personally think Stringer is one to something in this instance. Add his theory to how the modern human brain is wired and I think we may have the answer! If so, then that does NOT mean humans are getting dumber but simply that our brains are evolving and becoming MORE efficient which I think is most likely.
One theory connects our shrinking brains to the advent of agriculture when humans stopped being hunter-gatherers and became farmers. The initial effect of farming was a decline in human nutrition until our ancestors got the hang of it, so to speak. Protein and vitamins in the first farming diets were lacking, severely. Osteologists (scientists who study bones) can see this in ancient human bones from the time when farming began. Chronic malnutrition ensued and it was likely that the brains of the first farmers began to shrink as a result some theorize. One problem with this theory, however, is that farming didn’t arrive in Australia and Southern Africa until modern times yet brain size in those areas is decreasing just like everywhere else!
Some researchers believe our shrinking brain is due to global warming but there have been many eras of global warming in the past and brain size in human ancestors has consistently increased!
And then there is what is being called the “Idiocracy Theory.” Some researchers have found that brain size is connected to population density! They’ve noted that when human populations were low in the past that brain size grew but as human populations increased brain size began to shrink and this starting happening around 10-15000 kya!
Dr John Hawks has researched skulls dating from the Bronze Age 4000 years ago to the Middle Ages. His findings indicate human populations increased and brain size began to shrink more quickly than body size. Hawks says, “For a brain as small as that found in the average European male today, the body would have to shrink to the size of a pygmy!” He also discovered this process occurs in spurts and fits. He says the brain got smaller while the body remained about the same in most cases. Hawks says this trend is NOT alarming as he believes the reduction of brain size in modern humans might be a sign that we are actually getting smarter not dumber.
Hawks has noted that the brain is a energy consumer in a mega-way! In fact, our brains eat up about 20% of all calories we consume! He says a bigger brain takes longer to develop and uses more energy and brain size likely depends on how this all plays out. Perhaps, Hawks theorizes, the most intelligent brain consumes LESS energy! He notes that the greater the population, the greater the gene pool and, thus, the greater the chance of advantageous mutations. “Even Darwin knew this,” Hawks concludes, “and that’s why he recommended breeder maintain large herds.”
Hawks believes our brains have become better wired than those of our ancient human ancestors. More “streamlined.” Neurochemistry has likely shifted for the benefit of our species and our cognitive skills have been boosted as a result.
Recently, a frequent commentator on this blog named JR Bentley noted how his family bred horses and if new genes were not introduced into the breeding the animals would revert backwards eventually. The same is true with dogs and other animals. Is this now what is happening with humans? Does this explain our shrinking brains?
I tend to lean towards the idea that it’s not so much brain size as it is how the brain is wired. Homo erectus had a smaller brain than we do yet they were phenomenal explorers and colonizers spanning from Africa to Asia and I think even into the Americas! They were the first to use fire and were very innovative. They had to be in order to survive! Thus, I think H. erectus was intelligent and in terms of brain size even though they had smaller brains than we do today I believe their brains were wired magnificently! Further, Neanderthals had bigger brains that we do yet they were not the human species that survived to dominate the world. Homo sapiens were and we had smaller brains! I would say even though the Neanderthals had bigger brains than us their brains were not as well wired as ours.
Perhaps in our modern times (since 10 kya) our brains have evolved in terms of wiring and have become streamlined and more efficient perhaps eliminating the need for big brains. I don’t think humans are becoming more ignorant and, in fact, there are signs all around us attesting that we are becoming more intelligent in many ways especially in terms of technologies. We tend to think of evolution as a straight path upwards but this in fact is NOT the case at all. Human evolution has been one of ups and downs like a roller coaster or twisted vine. Perhaps with all of our modern advancements and technologies big brains are no longer required for our survival but, instead, smaller and more efficient brains are now required. In short, better wired brains are needed today.
Then, again, as with just about everything else in life usually there is no one singe cause to something like this as it typically turns out to be a combination of contributing causes. It might be that humans might be “evolving” into something beyond Homo sapien even! Our next step in evolution? Question is just what are we evolving into???
But then there is this to consider………………If the brain evolved (grew) faster than the body and now the brain is shrinking it is possible that we are actually devolving! Assuming this theory is true then the brain would shrink first and the body shrinkage would come later but how much later? Has our gene pool reached it’s end? Are new genes now required to keep us from going backwards? And if so then just what are we devolving into? Erectus? Habilis? Australopithecus? Ardipithecus? Or something else not yet known?
Well now this has got me thinking a lot and my little brain is exhausted and hurting so I’m signing off ………………. :0