See Also: Book Notes, (me), Notes on Consciousness, Happiness Hypothesis, Consciousness and the Brain, 7.5 Brain Lessons, Human: Makes Us Unique, Righteous Mind, Consciousness: Confessions, Blank Slate, Neuroscience of Human Relationships, Thinking, Fast and Slow

What is Health: Allostasis and the Evolution of Human Design

Peter Sterling <> Great Interview <> SciAm: Empathy

Book Page 32 page preface, 177 pages text, 38 pages of notes, 8 pages index.

This book is about human evolution from single cells, to our current state with the endemic health issues: obesity, hypertension and deaths of despair. One story arc is energy efficiency with deep dives into details like the 4000rpm nano-turbine that produces ATP (energy) to Watt's steam engine. The other arc is computational efficiency, chemicals ( hormones ) are cheaper than neural pulses. Specialized brain regions allow shorter wires and more computes. Fascinating science! well written! Usual disclaimer, not a summary, just things I want to remember.

Key for me: 1) Very clear model of how dopamine and the reward system work.
2) Cerebral specialization .. expands our species’ computational capacity. Yet each individual .. must rely on others to supply what’s missing.
3) Sacred rituals are needed to keep the tribe of varied individuals cooperating.
4) Three generation family model, because kids create a "caloric debt" until age 20 and do not pay it back until age 45.

image SterlingFig2_8.jpg

Sterling and Joseph Eyer coined the term Allostasis

p.xi - "For this model of “predictive regulation” to challenge homeostasis it would need a name. Therefore, advised by a professor of ancient Greek, we called it allostasis—meaning “stability through change.”

I wish every wizard who needed to coin a word would take as much care. And Allostasis and the predictive coding model have legs.

We depend on small pulses of dopamine for our well-being

The reward system sends small pulses when we solve a problem or find novelty. If we do not get them we sink into despair. If we use drugs, gambling, food, porn to flood the reward system with dopamine, it increases tolerance. The small pulses that reward problem solving do not increase tolerance. As Cozolino says: "When you depend on a substitute for love, you never get enough"!!!

p.41 - C. elegans’ neural mechanism for learning follows the mathematically optimal rule of reward-prediction error. Moreover, the worm brain’s internal signal to repeat a useful behavior is dopamine. This rule and this chemical signal have been used by all subsequent animals including flies and humans ... p.71 "So it is dopamine’s release in several key brain regions that delivers a pulse of “satisfaction.” We can live without daily rewarding pulses of dopamine — but we may not want to."

p.172 - "Since dopamine pulses are as essential to human health as vitamins, alternatives are sought in activities that deliver dopamine without effort and in large surges: the addictive drugs, rich foods, gambling, pornography, and so on. The medical profession and the biomedical research establishment seek to treat each problem technically.But there are reasons to doubt their likelihood of success. A more rational approach would be to develop new avenues to restore meaning and challenge to daily life—for everyone."

p.131 - "Modern sapiens has lost myriad sources of positive reward-prediction error: loss of rewards from reciprocal sharing and all the losses of satisfaction that accrue to the "less equal." For youth, there is loss of play and loss of learning that carries personal significance. Entering the "labor market" at peak physical capacity, most young adults are ciphers—of no individual significance—with rare opportunities for rewards by increasing mastery."

p.121 - "Clearly these systems [jch:dopamine/serotonin] are delicately poised to modulate many small decisions that matter in aggregate. When modern life becomes impoverished of daily meaningful decisions, the few remaining ones may generate larger regrets and correspondingly larger spikes of serotonin—in analogy to large surges of dopamine that drive the addictions. Current practice now treats this complex balance with an SSRI (selective serotonin reuptake inhibitor) that raises the steady level of brain serotonin. However, it seems doubtful that an SSRI could accomplish what is really needed: restore meaning to the activities of daily life."

Csikszentmihalyi's "flow state" is more than just dopamine hits, but that is a big part of it. A Review on the Role of the Neuroscience of Flow States in the Modern World

The Challenge of Human Differences

Sterling does not use the word tribe, but we evolved to be in small groups with neurodiversity. For any given problem, someone will likely have a better answer, but, with the distributed skills, it takes a village. As Sterling puts it: individuality enhances communal computational capacity.

p.159 - Each member of our species receives only a partial set of physical, intellectual, and emotional capacities. This allows cerebral space for some circuits to expand through practice while other circuits receive just enough territory to get by (see figure 4.14). This feature of human design extends the principle specialize from subcellular proteindiversity to the highest level of neural circuitry and behavior. Cerebral specialization, powerfully shaped by culture, continually expands our species’ computational capacity. Yet each individual, being incomplete, must rely on others to supply what’s missing. This core aspect of our design, extreme individuality coupled to extreme sociality, renders us awesome as a species, but the cost is individual suffering."

p.xxi - "A class of 20 medical students usually includes about one-third who are strongly empathic. Another third focus initially on “the lesion” but then reveal some empathic capacity. They grasp that Sacks’ question “What keeps a man together?” cuts deeper than “Where is the lesion?” They can appreciate the value of connecting these questions—of considering how Ave Maria might bind a fragmented personality. To support such students and foster that impulse, I replayed the tape annually for many years. The remaining students are obviously impatient with the story and the ensuing discussion. Fingers drum, legs jiggle, and eyes roll."

p.162 - H. sapiens’ individual strangeness affects the structure of communities and larger societies. By design, some of us are naturally empathic and altruistic, whereas some are naturally indifferent to others and narcissistic to the point of psychopathy. The former may become healers, and the latter may become political leaders. Empathy and psychopathy may well represent tails of a continuous trait distribution like height (see figure 6.8), but in any case they belong equally to our design and may have contributed equally to our survival."

Barrett on neurodiversity, p.101 - "It's important for humans to have many kinds of minds, because variation is critical for the survival of a species. One of Charles Darwin's greatest insights was that variation is a prerequisite for natural selection to work." How Autism Drives Human Invention by Simon Baron-Cohen

Sacred Practice Emerged Early

p.102 - "Sacred practice includes sex, music, dance, drama, and a multitude of unifying ceremonies surrounding birth, puberty, marriage, and death. It includes stories, jokes, and prayer. Such practices elicit intense emotions such as awe, joy, grief, and laughter—which somehow relieve intrapsychic and interpersonal tensions. The circuits that produce and process these activities occupy substantial cortical territory—our neural endowment for the arts. How language circuits would have paid their way seems obvious—but painting and music? Knowing that principled design uses expensive circuits only as needed, the neural investments to produce and process music, art, drama, and humor indicates their central importance to our success—probably by facilitating long-term cooperation between unrelated specialists."

p.161 - "Suffering from our conflicted need to cohere explains why art emerged early as part of our design (see chapter 4). So many paintings and sculpture, so many songs and poems, so many stories and jokes—all speak to human suffering. Art draws us together in bearing sacred witness to our suffering. We assemble to celebrate it—the Mass in B Minor in a Gothic cathedral, “Lift Ev’ry Voice and Sing” in an African American church, “Saint Louis Blues” in a honky-tonk bar—tears flow, tensions ebb, ecstasy rises, and blood pressure falls."
image SterlingFig5_1.jpg

We were dependent on three generations

Maybe this is so cool because I just became a grandfather!!

p.108 - "Leaving Africa 60,000 years ago, we traveled on foot in small bands that sometimes met up with other small bands to form a temporary larger group of, perhaps, 1,000 people. This occurred with sufficient frequency to allow bands to cooperate, exchange genes, and develop a common language. All group members were known to each other and usually related to some degree. We are unique among mammals for rearing multiple, dependent offspring of different ages and solved the problem of prolonged dependence by our three-generation family structure"

p.93 - "The human family structure permits a newborn to accumulate a huge caloric debt to caregivers over 20 years and then repay the debt over the next 25 years via caloric transfers to its children. Beyond age 45, when foraging skills peak, the positive transfers are mainly to grandchildren. .. the human life cycle must extend with sufficient vitality for individuals over 45 to contribute extra nutrition to expand the population beyond simple replacement; otherwise, it would risk extinction from random fluctuations."


1 Fundamentals of Efficient Design: The First Three Billion Years
2 On the Shoulders of Worms
3 Escape from Jurassic Park
4 On the Heels of Neanderthal
5 What Went Wrong?
6 What Is Health?
7 Summary and Conclusions

The Way We Were: Childhood

p.111 "Although there is plenty of instruction by adults, childhood among foragers is a lot about free play with minimal adult supervision. The following points draw on Peter Gray’s accessible book and references, but also from 15 years of personally observing three generations of a large indigenous family on our farm, their extended family, and our rural community in western Panama.

    Children in small communities are inevitably diverse in age, so the older children watch out for the younger ones. Moreover, the older children modify their games so that the younger children can participate. This encourages the younger ones to play at a level higher than they could manage in an age-matched group.An age-diverse group reduces bullying—because where’s the satisfaction in vanquishing someone half your size and age? Moreover, since all associations are voluntary and children usually want company, they quickly learn to settle differences, take turns, and so on."

p.126 - "As it turns out, learning in the right context is intrinsically rewarding. Neural circuits recognize when learning has occurred and trigger the reward circuit to deliver a pulse of dopamine that simultaneously provides satisfaction and boosts both learning and long-term memory. In other words, the learning mechanism fuels itself via intrinsic reward signals. When that fails in the classroom, we should be diagnosing not our children but the classroom. The diagnosis and treatment of ADHD will be further challenged in chapter 6." image SterlingFig6_6.jpg


Health is the ability to respond robustly to changing circumstances.

p.154 - "The allostasis model defines health as the capacity to respond optimally to fluctuations in demand. The definition applies across levels to internal systems, individuals, and social groups. And it applies to all sorts of demand: infection, cancer, mental disorder, social stress, and war."

p.135 - "We are afflicted with high levels of addiction, hypertension, obesity, and various cognitive and emotional symptoms. Something is certainly wrong, but as we shall see in tracing out the sequence of events, nothing can be identified as broken or missing. Another problem for the “machine model” concerns the spectrum of human variation and our extreme individuality. Chapter 4 explained that individuality enhances communal computational capacity. But some individuals are sooo different that they suffer and are also challenging to accommodate. .. again, nothing is demonstrably broken, but the machine model diagnoses a “disorder,” disease, or “dysregulation.” It assumes, even where nothing has been identified as broken, that eventually something will be — because that’s what the model requires."

p.152 - "The planetary rise in obesity is relatively recent, starting in the United States around 1980. It does not coincide with a sudden ubiquity of rich food—that stuff had been in US supermarkets since the 1950s. Rather, it is driven by unbounded consumption that does not satisfy. The less equal, less ! educated, and more stressed segments of the population rely on the same neural reward system as those who are better off, but the former have lower reward diversity, that is, fewer sources of positive reward-prediction errors that deliver dopamine (see chapter 5). Consequently, they are at greater risk for all sorts of addictions, including rich food. In short, the modern defect in obesity operates at the highest levels, reflecting an intense search for pulses of satisfaction."

p.113 - "Deaths of despair have risen for each new white cohort for 70 years (see figure 5.3, upper). Before World War II, the death rate from these causes was low and nearly flat with age, but it began to rise with the cohort born in 1945. That cohort, representing the early “baby boom,” was larger. As it entered the labor market in the 1960s, its size caused greater competition; plus there was a decline of labor unions and also a shrinking of blue-collar opportunities. Analyzing data available in the mid-1970s, Joseph Eyer predicted that each cohort would fare worse than expected based on their parents’ experience and would consequently suffer greater “stress-related mortality.”18 Figure 5.3 confirms this prediction. In contrast, blacks and Hispanics fared better than expected from their parents’ experience, and correspondingly their mortality has fallen."

Four principles of brain design:

  • First, signal with chemistry.
  • Second, minimize wire.
  • Third, send only what is needed.
  • Fourth, send information at the lowest possible rates.

    Full context of design principles example
    Figure 4.2 Longitudinal section through a mammalian brain (rat) illustrates four principles of brain design.
    First, signal with chemistry. Area postrema neurons
        (1) collect chemical information from the blood and send axons to neuroendocrine clusters in hypothalamus
        (2) whose axonal outputs to the pituitary organ (3) release chemicals (peptide hormones) into blood.
    Second, minimize wire. This is achieved by clustering functionally related neurons to prevent tangles that lengthen wires and by locating interconnected clusters close together. Thus, optic tract
        (4) signals slow changes in light level to the adjacent suprachiasmatic nucleus (5) that signals the diurnal rhythm to the adjacent neuroendocrine clusters.
    Third, send only what is needed.needed. For example, the mouse optic tract contains about 50,000 axons but sends fewer than 500 of the thinnest axons to the suprachiasmatic nucleus.
        Also, the hypothalamic pattern generators (6) integrate endocrine autonomic and behavioral responses but send only the conclusions" to low-level pattern generators in brainstem and spinal cord that execute the behavior (see figure 3.7).
    Fourth, send information at the lowest possible rates. Olfactory neurons collect chemical information from the air and send spikes to the main olfactory center (22) at low rates over the thinnest possible axons"


    p.80 - "Yet these principles still leave this question: how does the tiny hypothalamus manage so many diverse behaviors? Various neuron clusters in the hypothalamus integrate distinct sets of inputs regarding particular needs, such as thermoregulation, drinking, feeding, and sex."

    p.25 - "The hypothalamus is “mission control” for allostasis. It receives information from myriad sensors of the external and internal states, plus information from higher regions serving emotion, cognition, and memory. Each source provides a particular context for regulation. The clock may announce bedtime, but if dinner has not arrived, hunger takes precedence precedence over sleep. Danger or sexual opportunity may assert precedence over both. In evaluating the shifting hierarchy of needs, plus the opportunities and costs, hypothalamic outputs match mental state to behavior: hunger/feeding, thirst/drinking, sexual desire/mating. Accordingly, it sends chemical outputs—hormones—via the blood and electrical pulses via nerves to all the internal organs. This small structure, less than 0.3% of the human brain, manages all those functions by following design principles that save space and energy.

    p. - " So egalitarianism and reciprocal altruism were not romantic ideals—they simply made economic sense. Just as the energy efficiency of cooking was embodied in the structure of our teeth and gut (see chapter 4), so the energy efficiency of reciprocal altruism and egalitarian cooperation in foraging was wired into our innate social behavior."

    Not all prediction errors are equal

    The term "positive prediction error" is from the dopamine reward system. AFAIK, the prediction error in the low level predictive coding mechanism does not have a valence, only a precision. Stay tuned.
    Neural Circuitry of Reward Prediction Error Mitsuko Watabe-Uchida, Neir Eshel, Naoshige Uchida

    Specialization and variation of brain regions for mammals and specialization and variation of individuals within the group for Sapiens.

    Physics is a subset of biology -Gazzaniga 2021.05.09 jch