In this episode, we discuss Seven and Half Lesson about the Brain by Lisa Feldman. The conversation challenges common misconceptions about brain function, arguing that the brain's primary role is body regulation, not solely higher-level thinking. Barrett discusses the brain's development, emphasizing the pruning of neural connections and the impact of the environment on shaping the brain. Furthermore, the discussion explores evolutionary biology, rejecting the idea of humans as the pinnacle of evolution and highlighting the ongoing influence of cultural biases in scientific understanding. Finally, the interview touches upon the implications of these findings for individual and societal well-being.

Key Themes and Ideas:

1. The Limits of Our Understanding:

• We are far from fully understanding the brain. The speaker estimates we are only about "25 percent of the way there" with current measurement tools. However, this percentage is tentative, as new discoveries are expected to reveal previously unknown questions.
• Our current perspective might be limited, similar to seeing a limited spectrum of light. The complexity of the brain’s operation might be much greater than what we currently perceive. As the speaker put it, "when we're looking at the brain the way we look at it now we could be looking at you know very small spectrum of what of what you know the whole operation is".
• The tools we use to measure the brain are key, and better tools may reveal new layers of complexity we don't know to ask questions about yet.

1. The Brain's Primary Function:

• Contrary to popular belief, the brain did not evolve primarily for thinking. The speaker states emphatically, "the brain did not evolve for thinking."
• The brain's most important job is to keep the body alive and well. As the speaker notes, "the brain's most important job is to keep your body alive and well because frankly um you can look at the evolutionary story and it's certainly consistent with that but you can also just think well you know um if you if your brain isn't controlling your body you die."
• The brain evolved alongside increasing bodily complexity to manage these complex systems.

1. Debunking the "Triune Brain" Myth:

• The common idea of a “triune brain” with a layered structure—lizard brain (instincts), limbic system (emotions), and neocortex (rationality)—is a metaphor, not a literal description.
• This model is rooted in Western philosophical ideas that value rationality and depict emotional/instinctual parts as an “inner beast” needing control.
• The neocortex is not a recent evolutionary addition; most vertebrates share a very common brain plan. "Most of the what's called the neocortex where where rationality was assigned a home isn't new."
• Brains of different creatures may look different to the eye but are genetically very similar.

1. Evolutionary Perspective:

• Evolution is not a linear progression with humans at the “pinnacle.” Many ancestral forms still exist because their environments have remained relatively stable, not because they are less evolved. "Pressures on them have not changed and as a consequence they themselves have not changed."
• Genetic variation is the norm. What’s remarkable is when things stay the same due to strong selection pressures. The speaker explains, "if you just left things alone what you would see is that um that genetic change is the rule variation is the norm it's not the oddball".
• The idea that DNA has a "desire" to reproduce is anthropomorphic and scientifically inaccurate. The selection pressures act at the level of the organism, not the DNA. “Evolution it doesn't have a motive, neither does DNA”.

1. The Brain as a Network (Concept, not Metaphor):

• The concept of the brain as a network is not a metaphor but a literal description of a complex system of interconnected elements.
• The brain is comprised of billions of neurons and glial cells that communicate and produce outputs greater than the sum of their parts. The speaker states, "it's it's um you know billions and billions and billions of little elements that are constantly communicating with each other and producing outputs that are more than the sum of their parts meaning um that that when they work together they produce outputs that none of them could produce on their own".
• Metaphors, such as brain “wiring,” are useful but must be distinguished from the literal concept of a network.

1. Brain Development:

• Fetal brains produce an exuberant amount of neurons and connections, which are later pruned back based on environmental input. The speaker describes this as "an exuberance in the number of neurons"
• The brain "bootstraps" a model of its world, tuning itself to the specific physical and social environment it’s exposed to. "An infant brain is not a miniature adult brain it's a brain that is waiting for wiring instructions from the world".
• Caretakers play a vital role in curating the environment that an infant brain wires itself to, creating a major responsibility.

1. Subjective Reality and the Brain:

• Brains construct an internal model of the world, acting as a filter for all sensory data. "What the brain is doing is it's building an internal model of its body in the world and it's using that model as a filter for all incoming sensory data."
• This internal model makes it impossible to perceive the objective physical world directly.
• We don’t see or hear the world “as it is,” but as an internal reconstruction based on past experience, current sensory data and the brain's current internal state.
• The brain has a "spotlight of attention," which allows us to foreground certain features of the world and background others. "We have the ability to foreground um certain features of the world and background other features by virtue of this spotlight of attention that we have which basically allows us to choose to some extent what is signal and what is noise in the world".

1. Sensory Substitution and Technology:

• Scientific tools extend our senses, allowing us to perceive beyond the limitations of human senses. However, they do not give us a direct view, but instead translate data into forms our brains can process.
• Technology is sensory substitution, not sensory enhancement. For example, we can see things outside the visible spectrum by translating them into the visible spectrum to perceive them. "What we can do is detect things outside that spectrum and translate it into a visible spectrum so we can see it".

1. Humility and the Scientific Method:

• A scientific attitude involves humility, open-mindedness, and a willingness to revise beliefs based on new evidence. The speaker says, "the best way to say it is is this you know we know electron it's not that we discovered that electrons exist in the real world in the physical world what we know is that given our ability to measure things the way that we can something that is described well as an electron exists in the in the physical world but we that's that's about the best we can do right".
• Science aims to explain how things work, even when the answers are not always comfortable or fit our intuitions.

1. Body Budget and Metabolic Efficiency:

• The brain's primary function is to regulate the body's internal systems, maintaining a "body budget." The brain is "always running a budget for your body".
• Metabolic efficiency is a significant selection pressure.
• Uncertainty and new learning are metabolically expensive. "The most expensive thing that your brain can do is move your body or learn something new".
• Stress, sleep deprivation, unhealthy diet, social isolation and over-stimulation are all “taxes” that can bankrupt a body budget. "Each of these costs that you pay they're not like huge costs they're like little taxes little taxes that add up over time to a big deficit".
• When the budget is in deficit, the brain will slow down activity, reducing movement and learning, and cultivating "silos" of information to minimize metabolic cost.
• Even healthy food, if eaten when stressed, is metabolized less efficiently.

1. Social Regulation and the "Family Brain":

• While there isn't a "family brain" in a literal sense, social animals regulate one another's nervous systems. The speaker notes, "nervous systems all all animals who are social animals do this to some extent we do this though humans do this in remarkable ways including with the rays of an eyebrow or just a couple of words".
• Humans do this through remarkably subtle means, such as language, expression, and tone of voice.

1. The Primacy of Feelings:

• Our sense of feeling pleasant or unpleasant is more fundamental than our thoughts and shapes the way we experience and interpret the world. The speaker explains, "these feelings are like properties of consciousness to some extent they could be in the background they could be in the foreground but they're always there".
• Feelings are not “emotions” but simpler, more fundamental experiences arising from the body.
• Sense data from the body, experienced as feelings, may set the stage for the next round of thoughts.

1. Impact of Brain Understanding on Evolution:

• Understanding the brain can help us make more informed decisions about how we raise children, create policy (e.g. addressing childhood poverty) and improve societal well-being.
• The science is clear about how certain policies, like separating children from caregivers at the border, can cause significant harm.
• The knowledge that our brains and those of others are not fixed at birth but shaped by our environment can help to create more nurturing environments for development.

Conclusion:

This discussion provides a compelling challenge to traditional ways of thinking about the brain and our own existence. The key takeaways include the idea that the brain is primarily designed to keep the body alive and well, not simply to think; that it builds models of the world, not necessarily perceiving "objective" reality; and that the body's internal state deeply influences our thoughts and feelings. The discussion also emphasizes the importance of humility, the scientific method, and the potential impact our understanding of the brain can have on improving our lives and our society.

https://a.co/d/bS4Qt51