Extended notes for Seven and a Half Lessons About the Brain

This site accompanies the book Seven and a Half Lessons About the Brain by Lisa Feldman Barrett (Houghton Mifflin Harcourt, 2020).

Here you can find:

• Extended scientific notes for each lesson: ½ • 1 • 2 • 3 • 4 • 5 • 6 • 7
• A glossary of terms
• Errata
• Reviews
• Other recommended books and videos about the brain

Enjoy!

The Half-Lesson: Your Brain Is Not for Thinking

Jump to lesson: ½ • 1 • 2 • 3 • 4 • 5 • 6 • 7

Page	Quote	See this note	In appendix?
1	Amphioxi populated the oceans about 550 million years ago, and they lived simple lives.	Amphioxi populated the oceans about 550 million years ago	✔
1–2	Its meager nervous system included a teeny clump of cells that was not quite a brain.	A teeny clump of cells that was not quite a brain	✔
2	When you look at a modern amphioxus, you behold a creature very similar to your own ancient, tiny ancestor who roamed the same seas.	You behold a creature very similar to your own ancient, tiny ancestor	✔
2‌	The amphioxus didn’t need a brain. Its cells for sensing were connected to its cells for moving, so it reacted to its meager senses without much processing.	It reacted to its meager senses without much processing
2‌‌	Why did a brain like yours evolve?	Why did a brain like yours evolve	✔
2‌‌‌	It’s common to assume that brains evolved in some kind of upward progression—say, from lower animals to higher animals, with the most sophisticated, thinking brain of all, the human brain, at the top.	Brains evolved in some kind of upward progression
4	Both predators and prey evolved to sense more of the world around them. They began to develop more sophisticated sensory systems.	Predation
5	If [creatures] burned up energy fleeing from a potential threat that never arrived, they wasted resources that they might have needed later. Energy efficiency was a key to survival.	Energy efficiency is key to survival
5‌	You can think about energy efficiency like a budget.	Energy efficiency is like a budget
8	The scientific name for body budgeting is allostasis.	The scientific name for body budgeting is allostasis	✔
8‌	Prediction is such a useful capability that even single-celled creatures plan their actions predictively.	Single-celled organisms
8‌‌	...moving takes energy from the [creature's body] budget. The movement should be worth the effort, economically speaking.	The movement should be worth the effort, economically speaking	✔
9	Meanwhile, ancient animals continued to evolve larger, more complex bodies. That meant the insides of bodies became more sophisticated.	The insides of bodies became more sophisticated	✔
9‌	Newer animals, however, developed intricate internal systems, like a cardiovascular system with a heart that pumps blood, a respiratory system that takes in oxygen and eliminates carbon dioxide, and an adaptable immune system that fights infection.	Immune system
10	...a brain that efficiently supervises over six hundred muscles in motion, balances dozens of different hormones, pumps blood...	A brain that efficiently supervises over six hundred muscles in motion
10‌	Your brain’s most important job is to control your body—to manage allostasis—by predicting energy needs before they arise so you can efficiently make worthwhile movements and survive.	Your brain's most important job
11	Sometimes your brain budgets for the short term, like when you drink coffee to stay up late and finish a project, knowing that you are borrowing energy that you’ll pay for tomorrow. Other times, your brain budgets for the long term....	Short vs. long-term budgeting

Lesson no. 1: You Have One Brain (Not Three)

Jump to lesson: ½ • 1 • 2 • 3 • 4 • 5 • 6 • 7

Page	Quote	See this note	In appendix?
13	Your human mind, wrote Plato, is a never-ending battle between three inner forces to control your behavior.	Your human mind, wrote Plato	✔
14	...scientists later mapped Plato’s battle onto the brain in an attempt to explain how the human brain evolved.	Scientists later mapped Plato's battle onto the brain	✔
14‌	The outermost layer, part of the cerebral cortex, is said to be uniquely human and the source of rational thought; it’s known as the neocortex (“new cortex”).	Cerebral cortex
15	The triune brain story is one of the most successful and widespread errors in all of science.	One of the most successful and widespread errors in all of science	✔
16	And rationality and emotion are not at war... they do not even live in separate parts of the brain.	Rationality and emotion do not live in separate parts of the brain
17	Darwin asserted [that] each of us harbors an ancient inner beast that we tame through rational thought.	The Descent of Man
17‌	The astronomer Carl Sagan introduced the idea of the triune brain to the wider public in 1977 in his book The Dragons of Eden....	The Dragons of Eden
17‌‌	By the 1990s, experts had completely rejected the idea of a three-layered brain.	Rejecting the idea of a three-layered brain
17–18	In MacLean’s day, scientists compared one animal brain to another [by] squinting [through] a microscope. Neuroscientists who study brain evolution today still do this, but they also use newer methods...	Comparing animal brains
18	If we find the same genes in certain human and rat neurons, for example, then similar neurons with those genes were most likely present in our last common ancestor.	Genes were most likely present in our last common ancestor	✔
18‌	It turns out that as brains become larger over evolutionary time, they reorganize.	As brains become larger over evolutionary time, they reorganize	✔
18‌‌	Your brain has four clusters of neurons [...] collectively called the primary somatosensory cortex. In a rat brain, however, the primary somatosensory cortex is just a single region that performs the same tasks.	Somatosensory cortex
19	This arrangement among brain regions—segregating and then integrating—creates a more complex brain that can control a larger and more complex body.	Segregating and then integrating	✔
19‌	It’s a tricky business to compare brains in different species to discover what is similar....	Comparing brains in different species
19‌‌	...even if you do find the same genes in the brains of two different animals, those genes can have different functions.	Genes
19‌‌‌	Thanks to recent research in molecular genetics, we now know that reptiles and nonhuman mammals have the same kinds of neurons that humans do, even those neurons that create the fabled human neocortex.	Reptiles and non-human mammals have the same kinds of neurons that humans do	✔
21	The common brain-manufacturing plan begins shortly after conception...	The common brain-manufacturing plan	✔
22	...the human brain has no new parts. The neurons in your brain can be found in the brains of other mammals and, likely, other vertebrates.	The human brain has no new parts	✔
22‌	But the real question here is whether the human cerebral cortex has gotten bigger, proportionally speaking, relative to the rest of the brain.	Changes in brain size
24	There is no such thing as a limbic system dedicated to emotions.	There is no such thing as a limbic system dedicated to emotions	✔
24‌	The triune brain idea and its epic battle between emotion, instinct, and rationality is a modern myth.	The triune brain idea and its epic battle between emotion, instinct, and rationality is a modern myth	✔
25	Natural selection did not aim itself toward us — we’re just an interesting sort of animal with particular adaptations...	We're just an interesting sort of animal	✔
26	Perhaps rationality is better defined in terms of the brain’s most important job: body budgeting...	Rationality
26‌	...cortisol, a hormone that provides a quick burst of energy.	Cortisol
28	But feeling distressed is not evidence...that your so-called emotional brain has hijacked your supposed rational brain.	Amygdala hijack

Lesson no. 2: Your Brain Is a Network

Jump to lesson: ½ • 1 • 2 • 3 • 4 • 5 • 6 • 7

Page	Quote	See this note	In appendix?
29	Aristotle thought of the brain as a cooling chamber for the heart....	Brain metaphors
29‌	...a popular idea called phrenology portrayed the brain as a jigsaw puzzle,where each piece produced a different human quality...	Phrenology
29‌‌	A cooling chamber, a house for the soul, a jigsaw puzzle — these are all just metaphors, invented to help us understand what brains are and how they work.	Metaphors in science
30	Your brain is a network—a collection of parts that are connected to function as a single unit.	Your brain is a network	✔
31	Your brain, in turn, is a network of 128 billion neurons connected as a single, massive, and flexible structure.	A network of 128 billion neurons	✔
31‌	Generally speaking, each neuron looks like a little tree...	Types of neurons
31–33	This arrangement of axons, dendrites, and synapses knits your 128 billion individual neurons into a network. To make things simpler, I’ll refer to this whole arrangement as the “wiring” of your brain.	I'll refer to this whole arrangement as the "wiring" of your brain	✔
33	Your brain network is always on.	Your brain network is always on
33‌	Communication in your brain is a balancing act between speed and cost.	Neural communication must balance speed against cost
33‌‌	...over five hundred trillion neuron-to-neuron connections.	500 trillion connections
33‌‌‌	...you have a more frugal wiring arrangement that is sort of like the global air-travel system.	Airport metaphor
34	...neurons are grouped into clusters...	Neurons are grouped into clusters
36	Hub damage is associated with depression, schizophrenia, ...	Hub damage
36‌	You can thank natural selection for this lean and potent hub structure.	Hub structure
36‌‌	These chemicals, such as glutamate, serotonin, and dopamine, are called neurotransmitters, and they make it easier or harder for signals to pass across synapses. [...] some of these chemicals, such as serotonin and dopamine, can also act on other neurotransmitters to dial up or dial down their effects. When brain chemicals act in this way, we call them neuromodulators.	Neurotransmitters and neuromodulators
37	Neuromodulators and neurotransmitters together allow your brain’s single structure to take on trillions of different patterns of activity.	Neural configurations
37‌	Anytime you learn something—a new friend’s name or an interesting fact from the news—the experience becomes encoded in your wiring so you can remember it, and over time, these encodings can change that wiring.	Memory
37‌‌	As neurons change conversation partners, a single neuron can take on different roles.	Neurons can change conversation partners
37‌‌‌‌	...your ability to see is so intimately tied to an area of the brain called the occipital cortex that the area is routinely called the visual cortex...	The area is routinely called the visual cortex	✔
37‌‌‌‌‌	...if you blindfold people with typical vision for a few days and teach them to read braille, neurons in their visual cortex become more devoted to the sense of touch.	If you blindfold people with typical vision	✔
37‌‌‌‌‌	...the area is routinely called the visual cortex; however, its neurons routinely carry information about hearing and touch.	No brain area has a single psychological function
38	...neurons in the visual cortex become repurposed for other senses.	Visual cortex becomes repurposed
38‌	Some neurons are so flexibly connected that their main job is to have many jobs.	Many jobs
38‌‌	...one part of your famous prefrontal cortex, called the dorsomedial prefrontal cortex.	Dorsomedial prefrontal cortex
38–39	Even a simple reaching action [...] can be guided by different sets of neurons.	Simple act of reaching
39	This phenomenon is called degeneracy.	Degeneracy
41	A system has higher or lower complexity depending on how much information it can manage by reconfiguring itself.	A system has higher or lower complexity	✔
41‌	We’ll call this one Meatloaf Brain because its structure is so uniform.	Meatloaf Brain	✔
42	This brain is like a collection of specialized tools that work together, so we’ll call it Pocketknife Brain.	Pocketknife Brain	✔
43	If you have to move from the equator to Northern Europe, or from a laid-back culture to one with strict rules, you’ll adapt more swiftly with a complex brain in your head.	Laid-back vs. strict cultures
44	Octopuses can solve puzzles and even dismantle their tanks in aquariums.	Octopuses can solve puzzles
44‌	Some bird species can use simple tools and have a bit of language ability...	Birds
45	...genes are sometimes described as "blueprints." [...] Physicists sometimes say that light travels in waves...	Physicists sometimes say that light travels in waves	✔
46	...other kinds of brain cells, called glial cells, that function in ways that scientists don’t fully understand yet.	Glial cells

Lesson no. 3: Little Brains Wire Themselves to Their World

Jump to lesson: ½ • 1 • 2 • 3 • 4 • 5 • 6 • 7

Page	Quote	See this note	In appendix?
47	...an infant chimp can cling to its mother’s hair.	Hair or fur
47‌	...little human brains are born under construction. They don’t take on their full adult structure and function until they finish their principal wiring, a process that takes about twenty-five years.	Human brain development takes about 25 years
48	To a remarkable extent, a baby’s genes are guided and regulated by the surrounding environment.	Epigenetics
48‌	The brain areas that are most centrally involved in vision, for example, develop normally after birth only if a baby’s retinas are regularly exposed to light. An infant’s brain also learns to locate sounds in the world based on the specific shape of the baby’s ear.	Brain development and the world outside the brain
48‌‌	...a baby’s body requires some additional genes that sneak in from the outside world.	Additional genes sneak in from the outside world
48‌‌‌	A baby’s wiring instructions come not only from the physical environment but also from the social environment....	Wiring instructions from the social environment
48‌‌‌‌	When you cradle a newborn girl in your arms, you expose your face to her at just the right distance to teach her brain to process and recognize faces.	Learning to see faces
48–50	When you expose her to boxes and buildings, you’re training her visual system to see edges and corners.	Edges and corners
50	...causing gradual brain changes that we’ve called plasticity. These changes nudge the infant’s brain toward higher complexity via two processes we’ll call tuning and pruning.	Tuning and pruning
51	As neuroscientists like to say, “Neurons that fire together, wire together.”	Neurons that fire together, wire together	✔
51‌	A human embryo creates twice as many neurons as an adult brain needs, and infant neurons are quite a bit bushier than neurons in an adult brain.	A human embryo creates twice as many neurons
51‌‌	Both processes [tuning and pruning] continue throughout life.	Critical and sensitive periods
51‌‌‌	Your bushy dendrites keep sprouting new buds, and your brain tunes and prunes them. Buds that aren’t tuned disappear within a couple of days.	Dendrites keep sprouting new buds
52	These actions help the baby’s brain maintain its body budget, so her internal systems operate efficiently and she stays alive and healthy.	Caregivers help a baby's brain to maintain allostasis
53	... the "cocktail party effect."	Cocktail party effect
53‌	Your adult brain can effortlessly focus on one thing and ignore others, similar to a spotlight in the darkness.	Spotlight of attention
54	But the newborn brain doesn’t have a spotlight. It has more of a lantern...	It has more of a lantern	✔
54‌	They still lack the wiring that narrows their lantern into a spotlight.	Wiring that narrows the lantern
54‌‌	The infant brain is then able to construct its own environment of what is relevant to its body budget and what can be ignored. Scientists call this environment a niche.	Niche
55	After months of practice sharing attention with caregivers, an infant will learn to elicit shared attention from them.	Shared attention
55‌	When tested in a lab, newborns can distinguish a wide range of language sounds...	Newborns can distinguish a wide range of language sounds
55‌‌	Scientists think this sort of pruning may be one reason that children have an easier time learning languages than adults do.	Children more easily learn language
55–56	If people interacted with you in multiple languages when you were a baby, then your brain was likely tuned and pruned to hear and distinguish the sounds in those languages.	Multiple languages
56	...people tend to live around people of the same ethnicity, so babies are often not exposed to a wide array of facial features.	Faces of people who are from another ethnicity
56	Your brain assembles these sensations into a cohesive whole. Scientists call this process sensory integration.	Sensory integration
57	If you put a newborn on his mother’s belly, he will wriggle up to her breast by following the aroma.	Aroma of breast milk
58	In the 1960s, the Communist government of Romania outlawed most contraception and abortion. [...] As a consequence, hundreds of thousands of children were sent to live in orphanages.	Romanian orphans
59	When children are persistently neglected, in all likelihood they’ll suffer ill effects eventually.	Persistent neglect
60	This nontypical wiring imposes a pernicious burden on the body budget that accumulates over years, raising the odds of serious health problems later, such as heart disease, diabetes, and mood disorders like depression, all of which have metabolic underpinnings.	Body budget burden and health
60‌	Research shows that early and long exposure to poverty is bad for the developing brain.	Effect of poverty on little brains
61	Some kids are fortunate enough to be naturally resilient to the insidious effects of adversity and poverty.	Resilience to adversity
61‌	Childhood poverty is a colossal waste of human opportunity. Recent estimates suggest that it’s far cheaper to eradicate poverty than to deal with its effects decades later.	It's far cheaper to eradicate poverty than to deal with its effects decades later	✔

Lesson no. 4: Your Brain Predicts (Almost) Everything You Do

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Page	Quote	See this note	In appendix?
64	...I received an e-mail from a man who served in the Rhodesian army in southern Africa in the 1970s, before the end of apartheid.	A man who served in the Rhodesian army	✔
65	Your view of the world is no photograph. It’s a construction of your brain...	Vision is constructed
66	Faced with these ambiguous scraps of sense data, your brain must somehow figure out what to do next.	Ambiguous scraps of sense data	✔
66–67	Your brain assembles these bits into memories to infer the meaning of the sense data and guess what to do about it.	Your brain assembles these bits into memories	✔
67	Your past experiences include not only what happened in the world around you but also what happened inside your body.	What happens inside your body
67‌	The last time I encountered a similar situation, when my body was in a similar state, what did I do next? [...] what did I see next? What did I feel next?	The last time I encountered a similar situation
69–70	The painter Marcel Duchamp once said that an artist does only 50 percent of the work in creating art. The remaining 50 percent is in the viewer’s brain. (Some artists and philosophers call the second half “the beholder’s share.”)	The beholder's share	✔
70	...your brain also constructs what you feel inside your body.	What you feel inside your body
71	Neuroscientists like to say that your day-to-day experience is a carefully controlled hallucination, constrained by the world and your body but ultimately constructed by your brain.	An everyday kind of hallucination	✔
72	This whole constructive process happens predictively. Scientists are now fairly certain that your brain actually begins to sense the moment-to-moment changes in the world around you before those light waves, chemicals, and other sense data hit your brain.	Prediction
72‌	Water can’t possibly quench your thirst in a few seconds. So what relieved your thirst? Prediction.	Thirst and prediction
73	...Ivan Pavlov, the nineteenth-century physiologist who famously taught his dogs to salivate upon hearing a sound....	Ivan Pavlov
73‌	Imagine its smell, its taste, and how it feels in your mouth. Are you salivating yet?	Are you salivating yet?
74–75	... the winning prediction becomes your action and your sensory experience.	The winning prediction becomes your action
75	If your brain has predicted well, then your neurons are already firing in a pattern that matches the incoming sense data.	If your brain predicted well, then your neurons are already firing
77	Think about the last time you acted on autopilot. Maybe you bit your nails.	Acting on autopilot
78	All of us have had a nervous feeling before a test, but for some people, this anxiety is crippling.	Test anxiety
79	...determination seeds their brains to predict differently in the future so they can get their butterflies flying in formation.	Butterflies flying in formation
79‌	An organization called Seeds of Peace tries to change predictions by bringing together young people from cultures that are in serious conflict, like Palestinians and Israelis, and Indians and Pakistanis.	Seeds of Peace
80	Everyone who’s ever learned a skill, whether it’s driving a car or tying a shoe, knows that things that require effort today become automatic tomorrow with enough practice.	Automatic with practice
81	If your brain doesn’t merely react to the world but actively predicts the world and even sculpts its own wiring, then who bears responsibility when you behave badly? You do.	Who bears responsibility when you behave badly	✔
82	Things are different after you grow up. You can hang out with all kinds of people.	You can hang out with all kinds of people

Lesson no. 5: Your Brain Secretly Works With Other Brains

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Page	Quote	See this note	In appendix?
83	Part of being a social species, it turns out, is that we regulate each other's body budgets...	We regulate each other's body budgets
84	This co-regulation has measurable effects. Changes in one person’s body often prompt changes in another person’s body.....	Co-regulation
85	If your loved one is in pain, you can lessen her suffering merely by holding her hand.	Holding hands
85‌	...we live longer if we have close, supportive relationships with other people.	Living longer with close relationships
86	Another advantage of being a social species is that we do better at our jobs when we work with peers and managers that we trust.	Higher job performance
86‌	We may be healthier and live longer if we have close relationships, but we also get sick and die earlier when we persistently feel lonely....	Longevity and loneliness
87	This is one argument for why solitary confinement in jail—enforced loneliness—is like capital punishment in slow motion.	Solitary confinement
87‌	...when people are less familiar to you, it can be harder to empathize.	Empathy
87–88	...other creatures regulate each other’s body budgets. Ants, bees, and other insects do this using chemicals such as pheromones. Mammals like rats and mice use chemicals to communicate by smell, and they add vocal sounds and touch. Primates like monkeys and chimpanzees also use vision to regulate each other’s nervous systems.	Other creatures regulate each other's body budgets
89	In my research lab, we run experiments that demonstrate the power of words to affect the brain.	Experiments that demonstrate the power of words	✔
89‌	Why do the words you encounter have such wide-ranging effects inside you? Because many brain regions that process language also control the insides of your body,...	Many brain regions that process language also control the insides of your body	✔
90	We see similar wiring in other animals too; for example, neurons that are important for birdsong also control the organs of a bird’s body.	Birdsong
90‌	Brief withdrawals from your body budget followed by deposits create a stronger, better you.	Some stress is good for you
91	Over time, anything that contributes to chronic stress can gradually eat away at your brain and cause illness in your body. This includes physical abuse, verbal aggression...	Verbal aggression	✔
91‌	Simply put, a long period of chronic stress can harm a human brain. Scientific studies are absolutely clear on this point.	A long period of chronic stress can harm a human brain	✔
92	Two other studies, which I find remarkable as a scientist but unnerving as a person, measured the effects of stress on eating.	The effects of stress on eating	✔
95	We pay the costs of increased health care for illnesses, like diabetes, cancer, depression, heart disease, and Alzheimer’s disease, that are worsened by chronic stress.	Cost of illness
95‌	We also pay the costs of reduced innovation in a global economy, because when people are persistently stressed, they don’t learn as well.	When people are persistently stressed, they don't learn as well
95‌‌	Your brain already burns 20 percent of your body’s entire metabolic budget, making it the most “expensive” organ in your body...	Your brain is metabolically expensive

Lesson no. 6: Brains Make More Than One Kind of Mind

Jump to lesson: ½ • 1 • 2 • 3 • 4 • 5 • 6 • 7

Page	Quote	See this note	In appendix?
98	When people from the island of Bali in Indonesia are afraid, they fall asleep. Or at least, that’s what they’re supposed to do.	When people from the island of Bali in Indonesia are afraid, they fall asleep	✔
99	...people who grow up in Balinese culture, as well as in the Ilongot culture in the Philippines, do not experience what we Westerners call cognition and emotion as different kinds of events. They experience what we would call a blend of thinking and feeling, but to them it’s a single thing.	Thinking vs. feeling
99‌	The Himba people of Namibia often figure each other out by observing each other’s behavior, not by inferring a mental life behind that behavior.	Himba people and opacity of mind
100	[Greta] Thunberg’s mind is on the autism spectrum, and she says things that others aren’t willing to say.	Thunberg’s mind is on the autism spectrum	✔
100‌	Hildegard of Bingen, a twelfth-century scholar and nun, experienced visions of angels and demons and heard disembodied voices that were believed to come from God.	Hildegard of Bingen	✔
100‌‌	...humankind has a single brain architecture...	Humankind has a single brain architecture
101	[I'm] not saying people come into the world with their brains fully realized so that there’s a single, universal human nature. That’s the sort of mind that might emerge from Pocketknife Brain...	The sort of mind that might emerge from Pocketknife Brain	✔
101‌	One of Charles Darwin’s greatest insights was that variation is a prerequisite for natural selection to work.	Variation is a prerequisite for natural selection to work	✔
102	... variation is the norm — and is a blessing for our species ...	Variation is the norm
102‌	[Scientists] try to tame the variation by organizing it into categories. They sort people into neat little boxes with labels.	Taxonomy
102‌‌	Some people are labeled as having a warm personality, and others are cold. Some people are more dominant and others more nurturing.	Other categories of personality
102‌‌‌	Some cultures prioritize individuals over the group, while others do the opposite. Each box represents a feature of the mind that seems universal, and scientists use the boxes to catalog human minds.	Individualist vs. collectivist cultures
102‌‌‌‌	You may have seen personality tests that collect information about you and assign you to a little box. A great example is the Myers-Briggs Type Indicator...	Myers-Briggs Type Indicator	✔
102‌‌‌‌‌	...I prefer the Hogwarts Sorting Test, which has only four boxes and is far more rigorous.	Hogwarts Sorting Test
103	For example, homosexuality was listed as a psychological illness for many years in the official catalog of mental disorders maintained by the American Psychiatric Association.	Catalog of mental disorders
103–104	For example, many Western cultures draw strong dividing lines between the mental and the physical. [...] But in some Eastern cultures, such as those that practice Buddhism, mind and body are much more integrated.	Distinctions between body and mind
105	Feelings of affect range from pleasant to unpleasant, from idle to activated.	Feelings of affect range from pleasant to unpleasant, from idle to activated	✔
105‌	If you're a religious person, affect helps you feel connected to God.	Affect and belief in God
106	...your organs, hormones, and immune system are producing a storm of sense data, and you’re barely aware of it.	A storm of sense data
106‌	Your brain summarizes what's going on with your body in the moment, and you feel that summary as affect.	Interoception and affect
106‌‌	Affect is like a barometer for how you’re doing. Remember, your brain is constantly running a budget for your body.	A budget for your body
106‌‌‌	Ideally, evolution would have given you something more specific, like an app or a smart watch to regulate your body budget precisely.	An app or a smart watch to regulate your body budget	✔
107	Even though every human culture produces minds that feel pleasure, displeasure, calmness, and agitation, we don’t necessarily agree on what makes us feel these things.	Affect may be universal
108	These chemical modification last for only a short time.	Chemical modifications
108‌	Your mind must acclimate to the new culture. Scientists call this activity acculturation...	Acculturation
108‌‌	Even the simple question of what is food and what is not food can be an adventure in a new culture.	What is food
109	This is particularly true for the children of immigrants. They are of two cultures—their parents’ culture and their adopted culture—and have to pivot between two kinds of minds, which adds a burden to their body budgets.	Immigration and illness

Lesson no. 7: Our Brains Can Create Reality

Jump to lesson: ½ • 1 • 2 • 3 • 4 • 5 • 6 • 7

Page	Quote	See this note	In appendix?
111	We all live in a world of social reality that exists only inside our human brains.	Social reality
111‌	The boundary between social reality and physical reality is porous, and we can use scientific experiments to reveal this.	The boundary between social reality and physical reality is porous	✔
112	Scientists don’t know for sure how our brains developed this capacity, but we suspect it has something to do with a suite of abilities that I’ll call the Five Cs...	A suite of abilities that I'll call the Five Cs	✔
113	I've read about explorers in the 1800s who ventured into inhospitable, uncharted parts of the world, where many of them died.	Explorers in the 1800s	✔
114	...large brain size and high complexity are not enough to make and maintain social reality. You also need the fifth C, compression...	You also need the fifth C, compression	✔
115	...compression begins with small neurons that carry sense data from your eyes, ears, and other sense organs.	Sense data from your eyes, ears, and other sense organs	✔
116	...compression makes it possible for your brain to think abstractly...	Compression makes it possible for your brain to think abstractly	✔
117	Your brain compresses away the physical differences of these objects and in the process, you understand they have a similar function.	Abstraction and concepts
118	Each of the Five C's is found in other animals to varying extents.	The Five Cs in other animal species
119	In humans, however, the Five Cs intertwine and reinforce one another, which lets us take things to a whole other level.	The Five Cs intertwine and reinforce one another	✔
119‌	...as far as we know, humans are the only animal whose brains have enough capacity for compression and abstraction to create social reality.	Evolution of abstraction
120	If a troop of chimps agreed that whosoever pulls a particular stick out of the ground becomes king of the jungle, that would be social reality, because it imposes a sovereign function on the stick that goes beyond the physical.	It imposes a sovereign function on the stick that goes beyond the physical	✔
120‌	...evolution blended the Five Cs into a potion that spurs us to bend the world to our will.	Bend the world to our will
120‌‌	Social reality is human niche construction.	Niche construction
120‌‌‌	"We don't create a fantasy world to escape reality. We create it to be able to stay."	We don't create a fantasy world to escape reality. We create it to be able to stay	✔
120–121	[Social reality is] so powerful that it can alter the speed and course of our genetic evolution.	Gene-culture co-evolution
121	Another example is China’s one-child policy, which, in a culture that values sons over daughters, led to more male offspring than female and ultimately to millions of Chinese men who cannot marry Chinese women.	China's one-child policy
121‌	The concept of “race” often includes physical characteristics such as skin tone.	Physical characteristics such as skin tone	✔