Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Older estimates have long suggested that billion neurons in the human brain was the magic number, but some more recent research suggests that the brain actually contains fewer neurons than previously believed.
The human brain is made up of a complex network of neurons. These neurons serve as the building blocks of the nervous system, transmitting information to and from the brain and throughout the body.
You probably expect that a large number of neurons are required for such a complex process, but just how many neurons are there in the human brain? According to many estimates, the human brain contains around billion neurons give or take a few billion. This estimate has often been reported for many years in neuroscience and psychology textbooks and for many years was simply accepted as a relatively close approximation. Recently, however, Brazilian researcher Dr. Forget about discovering electricity or building airplanes.
There would be no time for looking at the stars and wondering about what could be. Our great ape cousins, ever the raw foodies, still have at most half as many cortical neurons as we do — and they eat over eight hours per day. But our ancestors figured out how to cheat nature to get more from less, first with stone tools and later with fire. They invented cooking and changed human history.
Eating is faster and much more efficient, not to say delicious , when food is pre-processed and transformed with fire. With plenty of calories available in much less time, new generations gained bigger and bigger brains. And the more cortical neurons they had, the longer kids remained kids, the longer their parents lived, and the more the former could learn from the latter, then from grandparents, and even great-grandparents.
Cultures soon flourished. The book he coauthored, Principles of Neural Science , is often considered a seminal work in the field of neuroscience. The journey Herculano-Houzel made to scientific discovery is impressive; it demonstrates a consistent skepticism that is essential for the development of scientific knowledge. In addition to refuting the billion neuron statistic, her research has refuted other long-held neuroscience dogmas.
As an example, until recently textbooks promoted the claim that glial cells a type of brain cell involved in numerous processes, including supporting nerve cells outnumber nerve cells ten to one in the human brain.
A search for an original source to support the claim failed. Counting brain cells allowed Herculano-Houzel to dispel that myth as well.
The paper was eventually published in the Journal of Comparative Neurology Azevedo et al. Even high-ranking science journals are sometimes resistant to change and do not necessarily practice the skepticism that is essential to scientific thinking. Azevedo, F. Equal numbers of neuronal and non-neuronal cells make the human brain and isometrically scaled-up primate brain.
Journal of Comparative Neurology — The thing is that this ratio between how many glial cells and how many neurons you have, that's highly variable across different parts of the brain. You can have two or maybe even three glial cells per neuron in some parts of the cortex, and less than 0. Getting those numbers for the first time was really exhilarating.
Before that we had mice and rats, which you know, they're just mice and rats. I remember thinking I know something that nobody else does. The next thought is, well I need to get the word out now because this is useless if I know this but nobody else does.
It was about the same thing with the humans with the bonus that once we had those numbers, we could actually start comparing them to other species and that's where you realize that compared to other primates we're just that generic primate with a 1. To me, that's the most important part about having the numbers. It's not just the numbers per say; it's what you can do with them. Narration: Why do you think people held on to the billion neurons myth for so long?
Herculano-Houzel: I think people very rapidly realized that we really did not know these numbers and we really needed those numbers, not just in the human brain, but in a number of other species if we were to find out some basic fundamental properties of how brains develop, how they evolve, how they're put together, how they function, what the constraints are.
The push back was really from people who were maybe very comfortable with the ideas, the notions that we had until then, that were really just based on intuitions like the human brain is special. It has to be, right, because we don't have the largest brain around, so how come we study elephants and they don't study us.
If their brain is this big and ours is just big enough to fit inside the head, there had to be something that's out of the ordinary about the human brain. When we came out and said that we really had just a large primate brain, that was on top of that, that was no much bigger than you would expect for the size of a primate body, some people could just not take that. You read in reviews that this cannot be true, which is just frustrating because that's not what scientists are supposed to say, that this cannot be true.
Fun science fiction aside, we are really the ones studying mice and elephants and what not, and not the other way around. I think it's very understandable to get this feeling that there has to be something very distinctive about humans.
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