A human story of our evolving brain

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Joseph Jebelli is a neuroscientist and writer. His research specialization focuses on neurodegenerative diseases, and alongside numerous academic articles on the brain, his work can be found in The Telegraph, The Guardianand the Welcome Trust.

Below, Joseph shares 5 key insights from his new book, How the Mind Changed: A Human Story of Our Evolving Brain. Listen to the audio version – read by Joseph himself – in the Next Big Idea app.

1. Humans have developed huge brains.

The first known human ancestor is called Sahelanthropus tchadensis, otherwise known as Toumaï, and had a tiny brain, around 350cc, about the size of a child’s fist. Ours are four times bigger, with spectacular capabilities that we are only beginning to understand.

Over nearly seven million years of human evolution, our brains have increased in size dramatically. Humans with 900cc brains began to appear, followed by humans with a capacity of 1000cc. Then, about 500,000 years ago, brain size jumped to 1,500 cc, the size of a cantaloupe. If the human brain has ever had a Big Bang, this is it.

Seven million years is not that long in terms of evolution. It’s amazing, then, that in what was essentially an evolutionary heartbeat, the brain went from consuming 8% of the body’s energy to 20%, despite only making up 2% of total body weight. . Although elephants and whales have larger brains than humans, our brains are three times larger than you would expect for an ape our size. Relative to body mass, we have the largest brains of any living creature.

There are many theories as to why humans have such huge brains. There is a theory that a rare genetic mutation shrunk the jaw and allowed the skull to expand. the invention of cooking saves energy that would have been used to digest raw food; and the activation of genetic switches that nearly doubled the number of neurons in humans compared to other great apes. In its colossal size, unique identity and marvelous eccentricity, the human brain has become our crowning achievement.

2. Emotions are a social construct.

Our brain has developed the neurobiological hardware to feel primary emotions, such as anger, surprise, disgust, joy, and sadness. It is not known exactly how this happened, but it is believed that the brain evolved at least two regions to do this: the amygdala (an almond-shaped structure buried deep in the brain) and the neocortex (the folded outer layer of the brain).

The amygdala is particularly important. As cognitive scientist Adam Anderson said, “If everyone is a stage, then the amygdala can be the emotional spotlight.” But our own influence on emotions is missing from this biological narrative. We are not the subjects of inexorable biological forces, but rather have the power to shape and control our emotions.

“We build emotions all the time. We are not born with them.

Take fear, for example. We have over thirty words in English for fear: panic, terror, worry, anxiety, trepidation, etc. But we all know that the fear of falling off a cliff is different from the fear of a job interview: one is a natural trigger, the other a socially constructed trigger. Both rely on evolved neural circuitry, but the constructed trigger is the product of what our environment has conditioned us to view as “scary.”

Or consider that people began to smile regularly in the Middle Ages thanks to improvements in dentistry. That’s not to say ancient people didn’t curl their mouths into something resembling a smile, but the smile we perform today is a constructed emotion.

We build emotions all the time. We are not born with them. They are not wired into the brain. When we think about that upcoming exam, or desire someone else’s possessions, or encounter an old flame, emotions of anxiety, envy, and love can automatically come and go. They are as fleeting and ephemeral as memory – and just as dependent on time. Compare what we think about the environment and gender roles today with what we thought only a few decades ago. The brain invents emotions, from moment to moment, to make sense of an ever-changing world.

3. Memory is not about the past.

When we think of memory, many of us imagine a giant library or filing cabinet in which files are ready to be accessed with the correct cues. In ancient Greece, Plato viewed memory as a wax tablet: our memories and thoughts could be stamped, stored and later retrieved. Socrates compared memories to birds in an aviary, saying, “some in exclusive flocks, some in small groups, and some flying alone, here, there, and everywhere among all the others.”

But that’s not why it evolved. Memory concerns the present and the future. When we reflect on experiences, we access past brain states to influence our current behavior and predict the future. Let’s say you’re hosting a dinner party and making a joke about accountants. The guests laugh politely, but you find out later that one of them is an accountant and was offended. Chances are you won’t make a similar joke again in the accountant’s business, not out of shame, but because you remember the negative consequences of your behavior. This is what neuroscientists call the self that remembers. This is how our brain plans the future.

The act of remembering is a type of learning. It is a constructive process that allows us to predict the future based on the past. This is why we are poor witnesses in court: our future-oriented memory is better able to imagine possible scenarios than to remember real ones.

“The brain is as much memory as the skeleton is bone.”

The reason scientists have misunderstood memory in the past is because of the language used to describe memory – terms like memory retrieval, memory acquisition, memory consolidation, etc. These terms presuppose the notion of memory as something distinct from the person who remembers. Language defines memory as separate from the mind, when in reality your brain does not store or retrieve memories. This is memories. The brain is as much memory as the skeleton is bone. As the novelist John Irving said, “You think you have a memory; but he has you!

4. Autism has played a crucial role in the evolution of the brain.

Autism is not a disorder, it’s just a different type of mind, a neurodiverse mind. The autistic brain functions differently from non-autistic brains and is often linked to increased intelligence, memory and attention to detail (systematization). For this reason, our autistic ancestors probably played a fundamental role in shaping early human societies by suggesting new ways of seeing the world.

For example, many people with autism possess a deep understanding of natural systems, which would have enhanced our understanding of calendar systems and maps. These were essential innovations in times of environmental conflict, such as the Ice Age. Additionally, people with autism often possess enhanced vision, taste, and smell. The incorporation of these skills into early human groups would have led to specialists within the community that would have been indispensable for tracking, hunting, and farming systems.

Art may have also benefited our autistic ancestors. Rock art, such as the paintings in the Chauvet Cave in southern France, demonstrate exceptional realism and a mysterious love of detail. Early humans relied on memorizing their surroundings, and the autistic brain’s ability to focus on parts rather than wholes would have made them skilled artists.

For many autistic people, a new understanding of how autism has shaped human evolution helps them see themselves as a diverse community of extraordinary individuals with unique brains, long oppressed by a dominant culture of unenlightened neurotypicals. and undisputed. It is indisputable that autism is with us for a reason, and without autism, human communities would not be where they are today. Autism should never be something to fix. This is one of the greatest spin-offs of brain evolution.

5. The future of human brain evolution is not what you think.

Our brains are still evolving, but more importantly, the very nature of brain evolution is also changing. New technologies such as brain-computer interfaces (BCIs), artificial intelligence, reprogrammable stem cells, and genetic tools such as CRISPR (a technology that allows scientists to make precision modifications to DNA) could forever changing what it means to be human.

Take the example of brain-computer interfaces (BCI). Many people now use BCIs. In 2017, researchers at the University of California, Irvine used BCI technology on a paraplegic man to restore his walking after a spinal cord injury. Other researchers are using BCIs to stimulate the visual cortex to treat the blind, restore lost connections in stroke victims, and scan the brain to detect depression. Treating the mind with dubbed machines electroceuticals has helped hundreds of thousands of people with hearing loss (using cochlear implants) and thousands of people with Parkinson’s disease and epilepsy (using deep brain stimulation).

“The next step for our brain may not be organic evolution.”

This technology allows humans to shape their own evolution. The first to do just that is Neil Harbisson, the world’s first officially recognized cyborg: a half-human, half-machine being. Harbisson has a rare genetic condition called achromatopsia, or complete color blindness, which means he sees the world in shades of gray. If you encountered Harbisson, you would notice a long black antenna protruding from its head, which translates wavelengths of light into musical notes. This gives Harbisson the extrasensory perception of literally feeling the colors in his head.

The next step for our brain may not be organic evolution. Futurist Ian Pearson imagines a future in which humans merge with machines to become a new species, called Cybernetic Homo. And it’s fascinating to watch a new movement called transhumanism take root, which aims to improve humans with genetic enhancements, self-repairing brains, and technological implants to such an extent that we become different, posthuman beings.

Nothing in our brain is fixed. In its endless cycles of change, its susceptibility to nurture, and its power to shape the world, our minds offer limitless possibilities.

To listen to the audio version read by author Joseph Jebelli, download the Next Big Idea app today:

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