The missed measure of man was overlooked during earlier investigations of human cranial capacity that focused on its relationship to intelligence. That is what the book to the right set about to disprove. Unfortunately, the subject of cranial capacity due to it’s ties to human intelligence has since become taboo to discuss due to political correctness. This is unfortunate because cranial capacity may play a key role in neurodegenerative diseases such as Alzheimer’s, Parkinson’s and multiple sclerosis and has nothing to do with intelligence. The missed measure of man that was overlooked is the design, layout and capacity of the posterior fossa in particular.
Some scientists once believed that there was a direct correlation between cranial capacity and human intelligence. It is a myth I cover in the last chapter in my book. The first problem is that there is no direct linear correlation between brain size and intelligence. If there were then elephants and whales would be smarter than humans. Similarly speaking, parrots have small cranial capacities but are far more intelligent (due to the way we test intelligence) than many mammals with much larger brains. Furthermore, regardless of race, females tend to have a smaller cranial capacity compared to males and Einstein, who was considered by many to be a genius, had an exceptionally small cranial capacity. In fact, his cranium was at the very low end of female capacity.
There is another problem and that is the way we measure intelligence. The brain is a survival organism. It’s job it to help us manipulate and master our environment. IQ tests are prejudiced against indigenous people who must master and remember many things about their environment and rely on ingenuity to survive and thrive. IQ tests fail to measure the subtleties and full spectrum of human intellect such as creativty, imagination and intuition among other things. Instead, modern IQ tests measure abstractions and memory in ways that may be important to people living in industrialized socities but are useless to indigenous people. Many people with so called high IQ’s wouldn’t be able to survive in similar circumstances. The bottom line is that the correlation between IQ and cranial capacity doesn’t work.
Presumably there are about one hundred billion nerves cells in the brain. Interestingly, the cerebellum sits in the posterior fossa and has more nerves that the rest of the brain put together. The truth is no one has actually counted. It is simply a guess based on average brain weight, the amount of fat and other factors. The average brain in humans weighs 1300-1400 grams or about 2.75-3.5 pounds. About half of it is fat. The rest of it is nerve cells. As far as we know for now, until proven otherwise, all humans are born with roughly the same number of nerve cells in the brain give or take a few billion or so. Bigger heads simply have bigger brains with larger nerves and more fat, not necessarily more nerves.
Nonetheless, a great deal of time and energy was wasted at the time measuring the size of the head and the capacity of the cranial vault. The famous book by Jay Gould pictured above was published in 1984 called The Mismeasure of Man. In it Gould refutes the arguements of the day, some of which were racially motivated.
Disregarding the old ignorant debates about cranial capacity and intelligence, there are many important issues to consider when it comes to race, gender and health. Just as females and males have different health concerns, certain health conditions have a higher incidence in particular races and ethnic groups. For example, thalasemia and sickle cells affect Asians and Africans far more than northern Europeans. Europeans living on the Mediterranean, however, are likewise effected. Thalasemia and sickle cell anemia are believed to have been protective mechanisms against malaria. The downside is they predispose afflicted people to anemia. Just as blood cells affect our physiology so does the design of the skull.
It is easy to see racial differences, including mixed races, simply by looking at the face. In this regard, it is interesting to note that the design of the facial part of the skull is intimately connected to the design of the base of the skull. They grow together during development and have a strong influence on one another. Their growth in childhood follows the musculoskeletal system of the rest of the body.
Together, the face and base of the skull determine the basic layout of the floor of the cranial vault. The bones that form the curved walls and cap the top of the cranial vault follow the growth of the brain. The cover over the cranial vault stops growing early in life when the brain stops growing in size.
There are significant racial and gender differences in the incidence of multiple sclerosis. There are also geographic differences but that’s a different story. When it comes to race, people of Asian and African descent appear to have a distinct advantage in that they appear to have a much lower incidence of MS than European people. When it comes to gender, regardless of race, females appear to have a distinct disadvantage in that they have a significantly higher incidence of MS compared to males. The difference in incidence in both race and gender may be due to design diffferences in the posterior fossa.
The white lines in the brain scan above represent the outline of the posterior fossa. The top line is missing because it represents the opening in the covering over the posterior fossa. The covering is called the tentorium cerebelli. The opening is called the tentorial notch or incisura. The scan is from a paper called, “Dimensions of the posterior fossa in patients symptomatic for Chiari 1 malformation but without cerebellar tonsillar descent,” by Sekula et. al., published in Fluids and Barriers of the CNS in 2005.
Among other things, a smaller or hypoplastic posterior fossa is more susceptible to Chiari malformations. In this regard, females most likely have a smaller posterior fossa compared to most males. They also have a higher incidence of multiple sclerosis compared to males.
Up until the eighth decade, they also have a higher incidence and get Alzheimer’s sooner than males. Females are also far more susceptible to Chiari malformations and to Dandy-Walker syndrome. Dandy-Walker syndrome, as you may recall, is related to enlarged ventricles and cysts that effect CSF flow mentioned in the previous post. The increased incidence of these particular conditions in females may have to do with the design of the posterior fossa, especially its capacity.
When it comes to race, a fairly recent orthodontic study on racial differences in craniofacial design done in Scotland showed that Europeans tend to have a shorter clivus in the base of the skull. This is interesting because a shorter clivus could decrease the capacity of the posterior fossa in Europeans compared to Asian and African designs. Thus, if the old arguments regarding a correlation between cranial capacity and IQ were true, then European brains would have fewer nerves compared to Asian and African brains. In addition to the capacity of the posterior fossa, other design issues to consider are the angles and pitch of the clivus and the tentorium cerebelli, as well as the angle of the base of the skull to the upper cervical spine.
Another issue to consider is, although they don’t get classic MS, Asians and Africans do get optic spinal multiple sclerosis and Devic’s disease. What’s more, Devic’s tends to be relatively more severe and disabling. Both optic spinal multiple sclerosis and Devic’s may be variants of multiple sclerosis due to design differences in the posterior fossa. The problem may lie in our method of diagnosing MS, which is based on classic lesions. Apparently, Asian and African people don’t get classic lesions. Aside from that, they otherwise get similar signs and symptoms. Consequently, many cases of MS among African and and Asian races may have been and continue to be overlooked and marginalized.
In addition, the condition of hydrocephalus is as old as the human race. It started with standing upright. All races are equally susceptible. Lastly, as we continue to learn more from upright MRI, just as I predicted in my book, it appears Chiari malformations also referred to as cerebellar tonsillar ectopia (CTE) are far more common than once thought. They can occur later in life due to trauma, aging and misalignments of the upper cervical spine that cause the brainstem to get pulled down or to sag slightly, due to low pressure, toward the base of the skull and into the foramen magnum. Tethered cords from a genetically short cord or from degeneration and abnormal curvatures of the spine can also cause CTE. Humans are susceptible to CTE by design and CTE can cause hydrocephalic-like conditions. Furthermore, hydrocephalic conditions and CTE may be at the core and cause of many neurodegenerative diseases. One of the causes lies in the design, layout and capcity of the posterior fossa. Other causes will be discussed as my blog and website continue to grow. For further information visit my website at www.upright-health.com.