New insights I got from The Dragons of Eden

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  • Mammals evolved to be nocturnal (became diurnal later):
    • World was dominated by reptiles.
    • Reptiles needed sunshine to be active.
    • Eggs are a rich source of nutrients.
    • They are unprotected at night.
    • We still eat eggs after we wake up.
  • Sleep-deprived animals generate neurochemicals in their cerebrospinal fluid, and the cerebrospinal fluid of sleep-deprived animals induces sleep when injected into other animals who are perfectly wide awake.
  • Sleep may not be as restorative as we imagine it to be:
    • There are humans who only need 1 to 3 hours of sleep at night, and they are fine.
    • It seems that we need REM sleep for long-term memory, but there seems to be no useful function of non-REM sleep! Comment: I wonder if we can get rid of it to get more hours in the day?
    • Mammals who went back into the water (whales, dolphins) have evolved to sleep very little.
    • Perhaps the function of sleep was to immobilise us during the day, to protect us from the reptiles dominating the world in our (mammals') early days.
  • Extinction of the dinosaurs: I. S. Shklovskii's hypothesis:
    • Nearby supernova releases immense flux of high-energy charged particles.
    • They destroy our ozone layer.
    • Excessive ultraviolet light wipes out large reptiles which depend on being in the sun for survival.
    • The mammals, sleeping hidden during the day, are fine.
    • We still have myths about dragons.
  • The concept of the triune brain: neocortex, limbic system, and R-complex (Reptilian complex).
    • R-complex: hierarchy (that is: who is better than who, mobbing to select outcasts and leaders), ritualistic, resistant to change. Limbic system: emotions, empathy, altruism, looking after the young. Neocortex: conscious awareness, rational, quietly observing the emotions, reasoning, reflecting, scheming, questioning.
    • An exceedingly beautiful metaphor. In the Platonic dialogue Phaedrus, Socrates likens the human soul to a chariot drawn by two horses — one black, one white — pulling in different directions, and weakly controlled by a charioteer. (The chariot is the neural chassis: spinal cord, hindbrain and midbrain. Hindbrain, also called the brainstem, includes the pons, cerebellum, medulla oblongata.) The two horses are the R-complex and the limbic cortex, and the charioteer "... barely in control of the careening chariot and horses ...", is the neocortex.
    • There are connections to Freud's id, ego, and super-ego, although the parallels are not clear-cut.
    • We share the limbic system with mammals, but not with reptiles.
  • Homo sapiens remained the only species at our level of intelligence. The fossil record of a few million years ago shows a great variety of manlike forms. We must have destroyed the others.
    • Myths of gnomes, trolls, giants, and dwarfs — perhaps a genetic or cultural memory of those times.
    • Only a few tens of thousands of years ago there were creatures with brains larger than ours, called Cro-Magnons and Neanderthals, who were better built than us. But we probably had larger frontal parts of the brain, while they had more well-developed parietal and occipital lobes, so we reigned supreme by virtue of teamwork, because the frontal lobes afford the making of more elaborate plans, and better predictions of the consequences of events.
  • Childbirth is generally painful in only one of the millions of species on Earth: human beings. This is to do with the size of the newborns' heads and also has to do with the wholesale reshaping of the pelvis.
    • Comment: this might be another example of things which are "evolutionarily new", like colour. If you experience a sense of newness when thinking about brilliant colours or the silhouettes of females, this might be because the older parts of the brain actually find them to be new.
  • The brilliant idea of the Gardners:
    • Chimpanzees seem to be quite smart.
    • Experiments show they are very poor at picking up language skills.
    • On the other hand, their dexterity is far superior to that of a human child at the same age.
    • Therefore, teach the chimpanzees American sign language.
    • They did. Washoe, Lucy, and Lana, among others, developed working vocabularies of 100 to 200 words.
    • Why hasn't this developed in the wild, on its own? It might have had, but humans probably systematically exterminated anything with signs of intelligence.
  • Large animals such as human beings average about 1 mutation per 10 gametes. Didn't know it was that much. That means 19% of us are mutants. I wonder if I am a mutant.
    • Actually, not that many, because some large proportion, maybe a vast majority, of these mutations will result in a genotype which won't be able to develop into a surviving machine. I'd like to know what is the percentage of newborns who are mutants.
  • The left brain is the bright and optimistic brain, while the right is dark and sad. Right hand (left hemisphere) is good, and left hand (right hemisphere) is bad. There are numerous examples of this embedded in etymology, for example.
    • Interesting experiment technique: Dimond employed special contact lenses to show films to the right or left hemisphere only. Then the subjects are asked to rate the emotional content of the films. There was a remarkable tendency for the right hemisphere to view the world as more unpleasant, hostile, and even disgusting, than the left hemisphere. Left hemisphere alone was similar to when both hemispheres are active, suggesting that it is mostly in control. (Maybe this has something to do with the left hemisphere seeing itself as good, and seeing the right hemisphere as bad: self versus other.)
  • The development of language might have been a consequence of the challenges of ice ages. Comment: is there an equivalent concept in evolutionary computation?
  • Mary Wollstonecraft Shelley wrote Frankenstein as part of a competition they made up with fellow travellers while immobilised in the Alps by inclement weather. Comment: another example of how workplace affects results.
  • James Clerk Maxwell invented the displacement current term essentially because the equations were aesthetically more appealing with it than without it.
  • Plants reject light in the part of the spectrum where it is most plentiful (green). Some plant species have noticed this and made appropriate adaptations. (For example, red algae have phycobilins, which accept energy from green and yellow and pass it to chlorophyll.)
  • Sagan is, as always, optimistic about communicating with extraterrestrial intelligence. Comment: who was it that said that our best chances of survival in this universe is to stay quiet? (I think Sagan is assuming that both us and them will be able to communicate, but neither travel. Yet he himself admits that other civilisations may know something about space travel that we don't suspect. So I think we ought to be more careful shouting into space.)
  • Quote: "I sometimes wonder whether the appeal of sex and aggression in contemporary American television and film offerings reflects the fact that the R-complex is well developed in all of us, while many neocortical functions are, partly because of the repressive nature of schools and societies, more rarely expressed, less familiar and insufficiently treasured."
  • One of the erroneous doctrines Sagan lists, among the Bermuda triangle, auras, and pyramidology, is "remote cutlery warping" :)
  • Quote: "Finding the solution to a problem is helped enormously by the certain knowledge that a solution exists."
  • Kemeny, who co-developed BASIC, was the president of Dartmouth, and made pioneering steps in making wide-spread use of computers for education at that school. Check out his biography, that's about as strong a collection of people to have worked with as it gets.
  • Comment: I am once again reminded, that we should max out our investment in education, on all levels. (Of course, to the detriment of all other fields of endeavour. But the investment will pay back for itself.)

Note: this was a 1977 book, so there are probably new insights to update the ones listed above. For example, we may have Neanderthal DNA.