Seven and a Half Lessons about the Brain summary

When we consider how the human brain evolved, we often look at it as a sophisticated thinking machine. But contrary to popular belief, our brains aren’t built for thinking. This is way too simplistic a take on the complex gray matter in each of our heads.

Our brains evolved from ancient underwater creatures like the amphioxi, which can sense their environment through basic skin sensations. One of the first big evolutionary steps involved learning to hunt and gaining the capacity for intricate movements. Another important aspect was allostasis or the body's ability to predict its needs before they arise, a trait even single-celled organisms possess. 

But as we grew in complexity, we needed brains that could efficiently regulate more and more of our bodies’ resources like water, oxygen, and glucose. This is our brains’ primary function: to be our bodies’ manager. They predict our energy needs, ensuring we can function optimally and survive, all in the service of nature's main objective: passing on genes.

Consider that a half lesson. In this Blink, we’ll learn seven more lessons that will shed light on the fascinating and complex organs sitting between our ears.

Now that we can recognize the fact of a single integrated brain, let’s delve deeper into its complex architecture: which is that of a vast, interconnected network. Instead of fixed compartments with specific functions, the brain's beauty lies in its intricate web, termed the "wiring." This wiring seamlessly connects about 128 billion neurons in a manner that’s both efficient and economical.

The brain's communication isn’t just about speed but also about being resource-efficient. Think of the neural network as being like the planet’s air-travel system. There aren’t direct flights between every city on Earth. Instead, all the destinations are efficiently connected through major hubs. There are over five hundred trillion connections between neurons, and while this number seems astronomical, it's actually a minimized version, ensuring the brain doesn't exhaust its resources all at once.

One of the most captivating aspects of this network is its adaptability, known scientifically as plasticity. Throughout our lives, the experiences we gather – from remembering names to learning new facts – reshape the neural wiring. This dynamic adaptability allows, for instance, the neurons in the visual cortex of babies born with cataracts to be repurposed for other senses.

In the vast web of the brain's network, a neuron doesn’t have a sole function. Its involvement can vary based on different cognitive activities. This network perspective underscores the brain’s dynamic behavior and flexibility, and it’s why we describe our brains as having "complexity."

Complexity isn't exclusive to humans, though. Despite our brains being among the most complex, various species demonstrate intelligent behavior due to their own uniquely structured yet complex brains. Consider octopuses; their brains stretch across their bodies and they show remarkable problem-solving abilities. Birds, too, exhibit traits of complexity, displaying tool use and rudimentary language skills, even without a cerebral cortex like ours. Our intricate brains aren't evolution's zenith, but are, instead, merely well-tuned to our environmental demands.

From our understanding of the brain's intricate network, let's dive even deeper into how these networks develop, particularly in young brains. The age-old debate of nature versus nurture often arises when discussing human development in particular. Yet, this distinction blurs when realizing how genes and environment dance together in the process of shaping us. For instance, the development of vision in babies depends significantly on exposure to light post-birth. An infant's auditory sense, too, tailors itself to the specific shape of its ears. Interestingly, some genes that influence our brains aren't even ours – they're from bacteria and other microbes that coexist within us.

When information journeys into a newborn's brain, certain neural pathways strengthen through frequent use, epitomizing the concept of plasticity. This leads to greater complexity in the infant's brain. Two critical processes at play are tuning and pruning. While tuning strengthens connections between neurons, making dendrites more intricate, pruning involves the degradation of seldom-used neural connections. The adage, “If you don’t use it, you lose it,” aptly describes this neural trimming.

Caregivers play a crucial role during this development phase. Their actions or inactions imprint on the young brain. For instance, rocking a baby to sleep every single night may prevent them from learning self-soothing techniques. Ideally, caregivers should strike a balance between providing support and allowing self-dependency. Over time, a child starts seeking validation and understanding from caregivers.

If a balance isn’t found, it can have long-lasting detrimental effects. For example, the 1960s in Romania witnessed countless children being sent to orphanages due to state policies, where many faced neglect. Researchers later found that many of these children, deprived of social needs, ended up developing smaller brains with fewer connections in key areas. This tragic lesson, although painful, underscores the essence of consistent, attentive caregiving.

Ultimately, the environments we create significantly impact how young brains wire themselves. It's imperative to nurture these environments, fostering growth and ensuring that young minds can thrive.

Navigating deeper into the labyrinth of the brain, we arrive at a fascinating mechanism that orchestrates our actions: prediction. Imagine if our brains solely relied on current sensory data; we'd be perpetually lost in a fog of uncertainty. Fortunately, our brains employ memories to craft a clearer path forward.

Contrary to the belief that our sensory organs provide a direct window to reality, it's our brains that interpret and assemble these sensory inputs and give them context. This means what we perceive – be it sight, sound, or touch – is a blend of external reality and our brains’ constructs. In essence, our daily experiences can be likened to controlled hallucinations. They're not the delusions requiring medical intervention, but rather our brains’ standard method to infuse meaning into sensory data, mostly occurring behind the curtain of our consciousnesses.

For instance, have you ever felt immediate relief after a sip of water, even though it's too soon to physiologically quench your thirst? This is your brain's prediction in action. By anticipating the sensory aftermath of hydration, it alleviates thirst before the water has had the chance to directly impact your system.

Yet, this predictive approach isn't a straightforward path. Faced with a situation, your brain churns out a multitude of predictions, weighing the likelihood of each one. Whether it's identifying a mysterious sound in the forest or identifying an unknown object, your brain selects a "winning" prediction that then shapes your sensory experience and actions.

And an interesting caveat emerges here: your brain doesn't always aim for accuracy. Its primary mission is survival. For instance, a soldier might persist with their brain's prediction of a threat even if it doesn't align with sensory inputs from their actual environment.

There's also an intriguing revelation: your brain often acts before you consciously decide. This prompts a profound question about free will. Are you merely a puppet of your memories and environments? Well, while it seems your choices may be initiated by unconscious predictions, you can often intentionally choose which environments you expose yourself to. This, however comforting, offers a semblance of free will.

Every day, you take part in an intricate dance between your brain and those of others. And it's not just a solo act; your brain both influences and is shaped by the interactions with the brains around you.

Remember how caregivers help mold infants’ brains? This mutual influence doesn't end in childhood. Throughout life, you unknowingly make deposits and withdrawals in the metaphorical body budgets of those around you. These exchanges can be beneficial or detrimental, impacting how you live and interact.

As you socialize, your brain is continuously adjusting. While some individuals are hyper-aware of their surroundings and interactions, everyone is influenced by someone. The intricate web of human connections means your brain's structure and functionality are influenced by those around you. Whether it's a loved one or a stranger, your body can resonate with theirs. Your heart rate might sync with theirs during a conversation, or you may mirror each other’s movements in unconscious, brain-choreographed dances.

Being inherently social provides you with numerous benefits. Close, nurturing relationships enhance your lifespan, and working in trustworthy environments boosts your performance. But the depth of these connections also has its downsides. Losing a loved one can feel like losing a part of yourself, as they played a role in maintaining your bodily balance. And connecting or empathizing with those unfamiliar to you may demand more from your body budget, making interactions occasionally challenging and overly draining.

Interestingly, the power of language transcends physical presence. A simple text can influence your biology, changing your heart rate or breathing pattern. This impact isn't metaphorical; your brain's language network, responsible for processing words, also regulates your body's core functions. In this way, words genuinely hold power in your neural wiring. They don't merely convey messages; they influence your biology and that of others.

Recognizing the power and influence your words and actions carry is paramount. True freedom incorporates responsibility. While you’re free to express yourself, you can’t escape the consequences of your expressions. Embracing your interconnectedness means understanding your impact and striving to be more nurturing, making more deposits into the body budgets of those around you.

Along with our discussion about the intricacies of the human brain, it's important to understand that brains can indeed develop into diverse kinds of minds. In fact, the sheer variety is staggering. Within a single culture, minds vary drastically. For instance, prodigious mathematicians can visualize calculations beyond ordinary comprehension. Meanwhile, figures like Greta Thunberg, with her mind on the autism spectrum, courageously confront global issues, attributing her unique perspective as a superpower. Historically, those with conditions like schizophrenia might have been revered as prophets or saints in certain societies.

In essence, humans are born with a foundational brain structure that can evolve into a plethora of different mindsets. Strikingly, the human mind doesn't seem to possess a sole, universal attribute. Some features thought unique to humans, such as spoken language, are absent in specific demographics like infants. Conversely, attributes like cooperation, present in nearly all humans, are also seen in various animals. Nevertheless, some mental characteristics are predominant, not because they're inherent but due to their sheer utility, such as the capacity for relationships.

A particularly salient and near-universal aspect of the human mind is the mood or affect. This constant underlying feeling, varying from pleasure to distress, is more persistent than fleeting emotions. It's a compass that guides our experiences, from the profound to the trivial. For the devout, it's a connection to the divine; for the spiritual, it’s a bond with the universe; and for skeptics, it fuels their certainties.

But how does your brain, consistently managing your body's resources, transform these physical processes into the mental experience of affect? It's a subject of ongoing intrigue in neuroscience.

Another fascinating dimension of the human experience is acculturation, not just across countries, but even transitioning between professional and personal domains. From learning the nuances of a new job to military personnel reintegrating post-deployment, your brain's adaptability in navigating these cultural transitions underscores its remarkable day-to-day versatility.

On the last stop of our journey into the fascinating world of the brain, we’ll now consider the idea that our brains have the astounding power to craft reality. This notion is demonstrated by how our different perceptions can be swayed by our beliefs: a wine is relished more when we think it's pricier, or how a mere "ecofriendly" label can make coffee taste better. Such perceptions are deeply rooted in the brain’s predictions influenced by the societal world we live in.

For such a creation of reality, a brain must have evolved to meet specific criteria. First, our brains need to be inherently creative. Second, they should be adept at communicating with other brains, allowing for the sharing of concepts like nations and their boundaries. Third is the ability to copy, which ensures we establish laws and norms harmoniously. Lastly, broad-scale cooperation is needed to ensure a unified, shared reality.

These capabilities – creativity, communication, copying, and cooperation – are among the five Cs that evolved due to genetic alterations, leading our species to possess large, intricate brains. Yet, mere size and intricacy don't suffice for creating and upholding social reality. That’s where the fifth C comes in: compression. Think of compression as our brains’ ability to craft extensive, layered summaries. This skill allows our brains to think abstractly, which, when combined with the other Cs, becomes the catalyst for creating a social reality.

Breaking it down: the cerebral cortex's architecture enables compression. This compression fosters sensory amalgamation, which then promotes abstraction. This abstraction gives way to the creativity that crafts flexible predictions not based on an object’s physical form but its purpose. Combined with communication, cooperation, and copying, the five Cs are born, creating and sharing our societal reality.

Although traces of these Cs are found in other species – crows being creative, elephants communicating, whales mimicking songs, ants cooperating, and bees abstracting through dance – it's the interconnectedness of these Cs in humans that elevates our capabilities, taking our experiences and realities to unparalleled heights.