Total number of neurons— not enlarged prefrontal region —hallmark of human brain
A new scientific study puts the final nail in the coffin of a long-standing theory to explain human’s remarkable cognitive abilities: that human evolution involved the selective expansion of the brain’s prefrontal cortex.
It does so by determining that the prefrontal region of the brain which orchestrates abstract thinking, complex planning and decision making contains the same proportion of neurons and fills the same relative volume in non-human primates as it does in humans.
“People need to drop the idea that the human brain is exceptional,” said Vanderbilt University neuroscientist Suzana Herculano-Houzel, who directed the study. “Our brain is basically a primate brain. Because it is the largest primate brain, it does have one distinctive feature: It has the highest number of cortical neurons of any primate. Humans have 16 billion compared with 9 billion in gorillas and orangutans and six-to-seven billion in chimpanzees. It is remarkable, but it is not exceptional.”
In her popular science book The Human Advantage: A New Understanding of How Our Brain Became Remarkable (MIT Press: March 2016), Herculano-Houzel explains how human brains grew so large, even larger than the brains of gorillas and orangutans, whose bodies are larger than ours. Her answer is surprisingly simple. It is the invention of cooking.
Cooking allowed early humans to overcome the energetic barrier that limits the size of the brains of other primates, she has determined. However, when the human brains grew larger they maintained the basic structure of the primate brain, including the size of the prefrontal cortex, her latest study has found.
The comparison of the relative size of the prefrontal region in primate brains is described in a paper titled “No relative expansion of the number of prefrontal neurons in primate and human evolution” by Herculano-Houzel and postdoctoral fellow Mariana Gabi published online this week in the Proceedings of the National Academy of Sciences early edition.
PR:
https://news.vanderbilt.edu/2016/08/09/total-number-of-neurons-not-enlarged-prefrontal-region-hallmark-of-human-brain/
Book:
https://mitpress.mit.edu/books/human-advantage
#neuroscience #humanbrain #evolution #science #neurons #research
I intuitively believed this theory was wrong all along. As a rough analogy, better algorithms don't correlate to more lines of code. Regarding the ratio to body size though, I don't see why that would be a relevant normalizing factor for cognitive regions of the brain. If I was twice as large as I am, why would I need twice as many neurons working on a math problem to solve it? ☺️
ReplyDeleteI wonder if those with highers IQ's actually have higher density of neurons, or it is just that they are more efficiently arranged? Why do some have IQ that is high and others don't, is it a genetic thing, or can it actually be trained? I'm not entirely sure as you can have a 'child genius', where their parents or grand parents weren't. Similarly, highly intelligent parents don't always have smart children
ReplyDeleteÈ sicuramente vero che a parità di neuroni una rete puó essere più efficiente di un'altra! Ma è altrettanto vero che una rete piu sofisticata richiede un numero maggiore di neuroni. Ne sà qualcosa chi ha provato a programmare in linguaggio macchina, avendo disponibili solo un numero limitato di celle di memoria. Un 286 risolve un problema di matematica, un Multicore di certo lo risolve prima, più velocemente ed è capace di risolvere cose talmente complesse che risultano impossibili per un 286.
ReplyDeleteI am a bit wary of how the singularity of what's possible to answer first to any question -- here the question "why?" -- may be overstating the case of whatever cause is selected for the role -- here, "cooking". I mean, tales we can tell perforce arrange their elements linearly, but causes can be simultaneous.
ReplyDeleteI simply cook...
ReplyDeleteStrange way to use analogies, I don't follow the authors and their conclusions.
ReplyDeleteLike for computers, more memory space doesn't involve a better efficiency, it's the software that makes the difference. What really matters is the organization, the connectivity, and mainly the plasticity of the connections, etc... You can add to the humanity specifications the langage and the writing that permit a rapid transmission of the knowledge, suitable with a life time (schools) and everything that makes a culture... Non-human primates have a limited culture, they barely transmit some technics to their youth and that's all, as far as we know.
I think the process of evolution is misunderstood by many and when it comes to the brain we still have a lot to learn. I like new ideas and approaches, maybe they're wrong ideas, but even so...the wrong paths will allow us to find the right ones.
ReplyDelete