Hi guys, today I want to talk about the change of human brain sizes and the possible
correlation with whoever created the megalithic structures. Brain size is one of the most obvious
traits that make us human. The volume of the human brain has increased and nearly tripled
as humans evolved for over 3 million years. With this dramatic brain size increase and the
largest brain to body mass ratio, humans became the most intelligent mammals on the planet.
We made tools, utilized fire, built homes and eventually started civilizations.
However, not too long ago scientists found a surprising reversal in our own species:
that human brains have been decreasing for quite a while and this brain size decline is about 5 times
faster than our body size changes, which means our intelligence level is potentially diminishing.
Believe it or not, our brains are now the smallest they have been
at any time in the past 100,000 years, over 10% smaller. The decrease is in contrast
to the general evolutionary tendency of the human cranial capacity to increase.
The timing and reasons for this decline are enigmatic. How and why did that happen? And how
does this change of human brain size shine light on the age of the megalithic sites?
300,000 years ago, around the time of the rise of our species, the brains of Homo sapiens had about
the same relatively large size as they do today. Researchers discovered that our brain size peaked
100k years ago and stayed stagnant for a while, then started to gradually decrease; some say
for the last 50,000 years, some say the last 40 or 12,000 years. Some argue that most of this decline
occurred in the last 6,000 years, some suggest the last 3,000 years. 100,000 years ago, the average
brain size was about 1,550 cubic centimeters or cc, compared to around 1,450 cc 12,000 years ago.
Many online sources state that our average brain size is 1,350 cc today. Though
a 2007 study indicates that in men the brain volume is around 1,260 cc and in women 1,130 cc.
That means we lost about 190 cc of brain – which is a bit bigger than the volume of a tennis ball.
This is really shocking, isn’t it? If our brain keeps dwindling at that rate,
over the next 20,000 years, it will be approaching the size of that found in Homo erectus, a relative
that lived half a million years ago and had a brain volume of only 1,000 cc.
Over several decades, a large quantity of evidence has consistently shown that bigger
brains tend to perform better at tasks related to intelligence. To clarify, it is not simply
the size of the brain that is relevant here, but the size of the brain in relation to body size,
referred to as the Encephalization Quotient (EQ). Research has found a close relationship between
intelligence and EQ. Hominin development has been marked as a result by increasing encephalization.
The Neanderthals had even bigger brains than modern humans.
Though they also had a bigger body therefore their EQ /brain to body mass ratio is smaller than ours.
Thus the Neanderthals were probably less intelligent than modern humans.
Some studies also pointed out that climate doesn’t seem to affect the human brain size development
thus the glacial or interglacial periods may not matter much to the change of brain sizes.
It is not clear why human brain size has been declining since the Late Pleistocene.
Nor do we know the impact, if any, to human cognition. Assuming relative brain size remained
evolutionarily advantageous to human species, encephalization would likely have continued
to increase. But our absolute brain size and encephalization have declined since 100k years
ago, and have been reducing at an accelerated rate during modern periods. This decrease in cranial
capacity is observed across the board to humans on every continent. Why did our brain size start to
shrink? There have been different theories to try explain the recent reduction in brain size, such
as self-domestication which means people became tamer and more docile to work with each other,
sexual selection, sociality, shifting cognitive demands to tools and technology, externalization
of knowledge, group-level decision-making and emotional plasticity. These are all conjectures
and so far there is no definitive answer on this alarming if not disturbing phenomenon.
Archaic hominins like Homo erectus made stone tools and managed to create fire
over 1 million years ago with a much smaller brain. For 100k years, the Paleolithic humans
had greater cranial capacity and higher EQ than modern-day humans, which indicates
that they were supposedly as intelligent as or even more intelligent than us now.
But somehow these people stayed in the Stone Age for almost 100,000 years. They
made better stone tools than the small-brained Homo erectus, but basically lived a similar life
style with comparable ancient innovations like bone needles, fire hearths and stone arrows.
That implies the bigger brain size of Homo sapiens didn’t really help with improving their overall
quality of life. If this was the case, then what’s the point of growing a bigger brain?
Please remember that brain growth and upkeep take a lot of energy. For our predecessors to develop
bigger brains, they needed more high-energy food. The consensus of scientists is that
brains are extremely expensive to both grow and maintain. Hominins with larger brains had
much higher resting metabolic rates. Even though the brain is only about 2% of our body weight;
it consumes almost a quarter of our energy input. Large brains also increase the risk of death
in childbirth. Evolutionary reasoning demands that species can afford to pay such hefty costs
only if they are outweighed by commensurate benefits. There must be a tremendous benefit
for human species to grow large brains which are particularly energy consuming.
Humans didn’t grow claws or long sharp teeth; we don’t run fast or climb as adeptly as many other
animals. Our survival and dominance are due to the development of our brains. There is little doubt
that a large human brain provides the machinery to execute complex cognitive tasks, including
tool making, forward planning, language use, innovation and social perception.
If so, then why did the large-brained Paleolithic people live like the small brained Homo erectus
and were only able to make minimal process on stone tool making for 100,000 years? If the
significantly smaller brains of Homo erectus were already capable of creating stone tools, I imagine
the archaic Homo sapiens with their larger brains should have accomplished much more. But yet we are
taught that they remained in the Paleolithic period and didn’t make notable innovations.
The Paleolithic period, or the Old Stone Age lasted for an incredibly long time,
it extends from the earliest known use of stone tools by hominins 3.3 million years ago,
to the end of the Pleistocene about 11,650 years ago. Now there is a conflict. We know
that bigger brains are extremely difficult to grow and maintain. If there is no substantial benefit,
then hominin brains shouldn’t have been growing for about 3 million years.
The growth of human brain size signifies there was an immense benefit of having larger brains.
Large brains, complex tools, and bipedalism are some of hallmarks of the human features.
Large brains and high encephalization should be beneficial to tool making. There ought to
be positive correlations amongst brain size, tool making skills, survival rates and overall species
establishment. But even though the Homo sapiens brain increased and peaked around 100k years ago,
there appears to be no significant technological advances around that time. Our ancestors stayed
in the Paleolithic era for another 88k years until 12k years ago. That means the larger brain
didn’t help in the improvement in tool making and other technical skills,
which contradicts the theory that larger brains are evolutionarily
advantageous and high encephalization generally indicates higher intelligence.
However, mysteriously, during the following 12k years, the same group of people jumped from
the Paleolithic period to Neolithic to Bronze Age, then Iron Age, all the way to Industrial
Revolution and built our modern society, while with a smaller brain size. How did this happen?
Why couldn’t they make such technological leaps sooner?
So our predecessors, the larger-brained Homo sapiens who were possibly as smart as or smarter
than us, only used stone tools and didn’t make much innovative growth for 100k years.
Then by some means the same people progressed from stone tools to traveling to the moon and
landing rockets on Mars in 12k years. Are we to believe that? If 12k years is the time needed to
establish a modern civilization rising from the Stone Age with our current reduced brain size,
then there should have been plenty of time for our ancestors who had higher EQ and bigger brains
to create something extraordinary too, right? But why is there no evidence of real ancient
sophisticated productions, other than stone arrowheads? What if there always has been
such evidence, though we don’t see it for what it really is? What if the world-wide
megalithic phenomenon was the creation of these ancient people with larger brains?
These mysterious places could be the footprints of this lost civilization.
Most known ancient megalithic structures and sites are located in Eurasia, Africa and South America.
They include the Giza pyramids, Petra, Baalbeck, Machu Pichu, Sacsayhuaman,
Puma Punku, Yangshan Quarry, Longyou caves and many more. Some sites show amazing precision cuts,
others contain huge stone blocks or giant caves, which engineers and architects find very difficult
to explain how they were constructed by ancient manual labor. Almost all megalithic structures
lack contemporaneous historical records; though that didn’t deter people from making assumptions.
For example, the Greek historian Herodotus, who has been called the “Father of History”
since he was the first historian known to collect his materials systematically.
He admitted that on many topics he was not an eye witness, and he was reporting only what had
been told to him. Maybe that’s why he made some questionable and subsequently proven wrong claims.
So much so that some people call him “the Father of Lies”.
Herodotus wrote about the three great pyramids of Giza being built for the ancient Egyptian kings,
Khufu, Khafre and Menkaure respectively, by enslaving their people. King Khufu’s reign was
around 2600 BC. Herodotus wrote about the pyramids in 450 BC, which is over 2,000 years after.
Where did Herodotus get his source of information? We don’t know. We need to consider how credible
is Herodotus' two millennia later story on the construction of the Great Pyramid.
He wrote about the great pyramid taking twenty years to build
and the base length is the same as the height. He thought iron was used during the construction.
Now we know that the Great Pyramid’s length and height are not the same, since the length is
83 m or 272’ longer. And if Herodotus was right about the pyramid’s building time,
then back then it was the Bronze Age with no iron. Herodotus probably tried his best with
the information he had and likely juiced it up to attract readers when he described
the ancient structures and events, which happened 2,000 + years before his time. Therefore his
account on the pyramids might not be very trustworthy. Archaeological academia, however,
subscribed to Herodotus’ claim and attributed the Great Pyramid to the dynastic king Khufu.
What I’m saying is that, the pyramids, among other magnificent megalithic sites might have
a much longer history. The constructions of Egyptian pyramids, the massive stone boxes
in Serapeum or the uniformed tool marks in Longyou caves or Petra are highly advanced.
Many experienced stone masons and experts in the construction field
have confirmed that these sites were not created by hand chisels. On the contrary,
they exhibit signs of amazing sophistication that are on par or surpass our modern construction
or mining machinery. These places are ancient. Their scopes of works are beyond slave labors,
hand tools or draft animals. Is it possible that these sites were the work of the larger-brained
modern humans who lived for hundreds of thousands of years in the past?
Earlier I talked about the strange absence of superior tools
even though the late Paleolithic people had larger brain capacities.
Humans evolved for millions of years and finally achieved the large brain size
and higher cognitive ability. They should have accomplished a lot more than stone tools
because even the small-brained Homo erectus had made flint tools over 1 million years ago.
What if the megalithic sites were the remnants left from a previous sophisticated civilization
created by our ancestors, the modern humans who were higher encephalized with larger brains?
It seems that this civilization only left megalithic structures without
other evidence. Why there are no artifacts, leftover tools or machinery to be found?
Assuming this civilization was built after the peak of the brain size which is over 100k years
ago, and it took about the same 12k years to progress from Paleolithic to Neolithic,
Bronze Age, Iron Age and forward - then the machines created and used by this civilization
would be about 30,000 years old. Metal objects rust away fairly quickly, like in a few hundred
to a thousand years or so. Surviving metal might be scavenged and recast later.
Some metal might have deteriorated to a state where it looks like hematite.
Also, remnants from that long ago would likely be buried either very deep underground, possibly
under 20 m/ 66’ of sediments, or submerged by water and sea. Though I think it’s possible
that we will find some signs of ancient machinery in the future, like how the over 2,000-year old,
lost technology of the Antikythera mechanism got pulled out from an ancient Greek shipwreck.
Ok, I’ll wrap it up here. Let me know what you think of my hypothesis on the brain size change
and what it might tell us about the megalithic civilization.
I plan to make another video discussing the relationship between the Paleolithic settlements
found by archaeologists and this possible advanced civilization. Please stay tuned.
If you have any insights, please leave me a comment. If you like my video,
please give me a thumb’s up and subscribe. I have a wide range of topics that I want
to share with you. This is Curious Being, I am Tina. Thanks for watching and see you next time.