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September 15 - October 28, 2024
the second law of thermodynamics. That unbreakable law of physics which declares that entropy—the amount of disorder in a system—always and unavoidably increases; the universe cannot help but tend toward decay.
mysterious process scientists call abiogenesis: the process by which nonbiological matter (abio) is converted into life (genesis).
cyanobacteria, also called blue-green algae—found
Sugar is produced only by life,
Gastrulation, neurons, and muscles are the three inseparable features that bind all animals together and separate animals from all other kingdoms of life.
what is now known as rate coding. The idea is that neurons encode information in the rate that they fire spikes, not in the shape or magnitude of the spike itself.
dopamine was a signal for the anticipation of a future good thing, not the signal for the good thing itself.
serotonin is the satiation, things-are-okay-now, satisfaction chemical, designed to turn off valence responses.
Adrenaline not only triggers the behavioral repertoire of escape; it also turns off a swath of energy-consuming activities to divert energetic resources to muscles. Sugar is expelled from cells across the body, cell growth processes are halted, digestion is paused, reproductive processes are turned off, and the immune system is tamed. This is called the acute stress response—what bodies do immediately in response to negative-valence stimuli.
Evolution embedded an ancient biochemical failsafe to ensure that an organism did not waste energy trying to escape something that was inescapable; this failsafe was the early seed of chronic stress and depression.
Learning was not the core function of the first brain; it was merely a feature, a trick to optimize steering decisions. Association, prediction, and learning emerged for tweaking the goodness and badness of things.
smell recognition is nothing more than pattern recognition.
if there is a mismatch—if an incoming pattern is sufficiently new—then this triggers a process of neuromodulator release, which triggers changes in synaptic connections in the cortex, enabling it to now learn this new pattern.
the invariance problem: how to recognize a pattern as the same despite large variances in its inputs.
In vertebrates, surprise itself triggers the release of dopamine, even if there is no “real” reward. And yet, most invertebrates do not exhibit curiosity;
Carbon dioxide levels plummeted, which caused the climate to cool. The oceans froze over and gradually became inhospitable to life. This was the Late Devonian Extinction,
the Permian-Triassic mass extinction event, which occurred around 250 million years ago, was the deadliest of all extinction events in Earth’s history. It was the second great death in this era. This extinction event was the most severe and perhaps the most enigmatic. Within five to ten million years, 96 percent of all marine life died, and 70 percent of all land life died.
The electrical signaling of neurons is highly sensitive to temperature—at lower temperatures, neurons fire much more slowly than at warmer temperatures. This meant that a side effect of warm-bloodedness was that mammal brains could operate much faster than fish or reptile brains.
you cannot imagine things and recognize things simultaneously.
When you imagine moving certain body parts, the same area activates as if you were actually moving the body parts.
The neocortex seems to be in a continuous state of predicting all its sensory data. If reflex circuits are reflex-prediction machines, and the critic in the basal ganglia is a reward-prediction machine, then the neocortex is a world-prediction machine—designed to reconstruct the entire three-dimensional world around an animal to predict exactly what will happen next as animals and things in their surrounding world move.
The same networks get activated when you’re imagining the future as when you’re remembering the past.
akinetic mutism—a tragic and bizarre condition caused by damage to certain regions of the prefrontal cortex in which people are able to move and understand things just fine but they don’t move, speak, or care about anything at all.
“Why did the AI system do that?,” we are asking a question to which there is really no answer. Or at least, the answer will always be the same: because it thought that was the choice with the most predicted reward.
animals who fell into the strategy of group living evolved tools to resolve disputes while minimizing the energetic cost of such disputes. This led to the development of mechanisms to signal strength and submission without having to actually engage in a physical altercation.
mentally rehearsing actions improves performance when actually performing actions.
some animals should be able to plan but unable to anticipate future needs (such as rats).
there is no neurological structure found in the human brain that is not also found in the brain of our fellow apes, and evidence suggests that the human brain is literally just a scaled-up primate brain: a bigger neocortex, a bigger basal ganglia, but still containing all the same areas wired in all the same ways.
memes. This word was later appropriated for cat images and baby photos flying around Twitter, but he originally meant them to refer to an idea or behavior that spread from person to person in a culture.
language emerges not from the brain as a whole but from specific subsystems.
language is not an inevitable consequence of having more neocortex. It is not something humans got “for free” by virtue of scaling up a chimpanzee brain. Language is a specific and independent skill that evolution wove into our brains.
Humans, however, have two communication systems—we have this same ancient emotional expression system and we have a newly evolved language system in the neocortex.
The gestures of monkeys are automatic emotional expressions and don’t emerge from the neocortex; they are more like a human laugh than language.
Our ancestors began shifting toward eating meat. Only about 10 percent of the diet of a chimpanzee comes from meat, while evidence suggests that as much as 30 percent of the diet of these early humans came from meat.
Homo erectus became a hypercarnivore, consuming a diet that was an almost absurd 85 percent meat.
Cooking enables animals to absorb 30 percent more nutrients and spend less time and energy digesting. In fact, modern humans are uniquely reliant on cooking for digestion. Every human culture uses cooking, and humans who attempt to eat fully raw diets, whether raw meat or raw vegetables, have chronic energy shortages, and over 50 percent become temporarily infertile.
One theory is that menopause evolved to push grandmothers to shift their focus from rearing their own children to supporting their children’s children.
the problem of finding an evolutionary explanation for language has been colloquially dubbed “Wallace’s problem.”
“exaptation,” which is when a trait that originally evolved for one purpose is only later repurposed for some other purpose. An example of exaptation is bird feathers, which initially evolved for insulation and were only later repurposed for flight—it would thereby be incorrect to say that bird feathers evolved for the purpose of flight.
Around seventy thousand years ago, Homo sapiens began their first adventure out of Africa.
by forty thousand years ago, there was only one species of humans left: us.
human brains have an automatic system for predicting words (one probably similar, at least in principle, to models like GPT-3) and an inner simulation.
By self-replicating, DNA finds respite from entropy, persisting not in matter but in information. All the evolutionary innovations that followed the first string of DNA have been in this spirit, the spirit of persisting, of fighting back against entropy, of refusing to fade into nothingness.
