Dragons of Eden by Carl Sagan won the Pulitzer Prize for Non-Fiction in 1978
Natural selection has served as a kind of intellectual sieve, producing brains and intelligences increasingly competent to deal with the laws of nature.
There isn’t much discussion of dragons, beyond a short snippet on Komodo dragons, in this book but Sagan uses this metaphor as a catchy title to highlight that this fear may be part of our own mammalian evolution. The dragon concept is buttressed by so many old tales throughout numerous civilizations that Sagan implies there must have been a fearsome dragon or related animal in our distant past that shaped our evolution. I am not convinced per se but the rest of the book is much more serious than this topic.
Carl Sagan is arguably the greatest science writer and educator of recent times. In this book his mind, through his theories, is on full display for all to see. He steps through various evolutionary ideas about how man (and his brain) has evolved.
As has been stated in other reviews of this book, a mark against it is that some sections are now outdated. Science evolves. Yet, for me, it is remarkable even when discussing a mundane game of ‘Pong’ that Sagan is able to foresee many of our challenges we face today. He even talks about the danger of computers and video games pre-empting children from learning the proper fundamentals of math and science. As a parent, there is little argument from me on this point.
At its core this is a thought provoking book that resonates. It is short at only nine chapters so I will review the chapters here — because many are true gems and the rest are pretty good.
Chapter 1 — The Cosmic Calendar
In this chapter Sagan famously maps the age of the universe, nearly 14 billion years, into a single year. We see that if the Big Bang starts on January 1st at 12:01 am, then humans don’t arrive to the timeline until December 31st at 10:30 pm, and all of our recorded history can be confined to the final 10 seconds of the year! Powerful stuff.
Chapter 2 — Genes and Brains
The average human brain has 10^13 synapses. This means there are 2^(10^13) possible states of a single brain, a number that approaches the number of atoms in the universe. We also learn that “The simplest organisms on Earth today have just as much evolutionary history behind them as the most complex”. In other words even simple diatoms are well honed and efficient machines.
Chapter 3 — The Brain and the Chariot
Humans have a very high brain to mass ratio relative to any other animal on the planet. Sagan goes on to discuss sleep and posits a theory that land mammals sleep so much because they can hide and are less vulnerable than marine mammals. For example dolphins rarely sleep, sometimes only for a minute at a time. I will take it a step further and say that land mammals may also sleep so much because it is difficult for most, not all, mammals to find food in the dark. Isn’t it better to burn as few calories as possible through sleeping those night time hours away. Whatever the real reason, this trait goes back to the end of the dinosaur era.
Chapter 4 — Eden as a Metaphor
“paleontologists have deduced that “bipedalism preceded encephalization,” by which they mean that our ancestors walked on two legs before they evolved big brains.” It seems that hunting developed brains further in this regard.
Chapter 5 — The Abstractions of the Beasts. My favorite chapter. It’s largely about how humans have developed verbal speech and a large part of our oversized brains are dedicated to this function. But it also discusses how incredibly smart chimpanzees are and how presumptuous humans are about or lack thereof intelligence in all animals. It seems that this view is because they don’t have vocal chords. Scientists have taught select chimps sign language and they have learned to use words correctly and in context (nouns, verbs and adjectives) to the tune of vocabularies in excess of one hundred words. The chimps can even sign curse words when humans introduce illogical steps into a food reward scheme. The average human uses just 1,000 common words in everyday speech and some mentally impaired humans don’t even reach that level. Sagan implies that due to the chimpanzee’s small brain volume it is unlikely they can ever achieve normal human level language. However it is clear that chimps (and many other animals) feel anxiety and think in ways that are much more in line with humans than I ever knew. The implication here is that the inability to verbalize word constructs, i.e. language, is what has kept other animals from evolving. Although dated, this chapter alone is worth the price of the book or a trip to the library.
Chapter 6 — Tales of Dim Eden
This chapter primarily revisits the topic of sleep first broached in chapter 3 and talks a good deal about dinosaurs. Maybe this section should have been combined with The Brain and the Chariot.
Chapter 7 — Lovers and madmen
This chapter is heavily focused on brain hemisphere functions and the tie-in to evolution. Very informative.
“M. S. Gazzaniga of the State University of New York at Stony Brook suggests that hemispheric specialization occurs because language is developed in the left hemisphere before the child acquires substantial competence in manipulative skills and geometrical visualization. According to this view, the specialization of the right hemisphere for geometrical competence is a specialization by default—the left hemisphere’s competence has been redirected toward language.”
Chapter 8 — The Future Evolution of our Brain.
“In general, human societies are not innovative. They are hierarchical and ritualistic. Suggestions for change are greeted with suspicion: they imply an unpleasant future variation in ritual and hierarchy: an exchange of one set of rituals for another, or perhaps for a less structured society with fewer rituals. And yet there are times when societies must change.”
Wow. This is such a well articulated statement. Most of us recognize this type of change is the fundamental impediment to solving many of our country’s problems and by extension in solving the world’s environmental and population problems. Sagan goes on to wade into the abortion debate as well. He also talks about tech and its benefit and possible detriment to children. Not a cohesive chapter by any stretch and outdated perhaps, but still thought provoking.
Chapter 9 — Knowledge is our Destiny
An intriguing chapter where Sagan speaks of aliens. It is his belief that while their physical forms will be unfamiliar to us, their minds will be similar
“Organisms throughout the universe should therefore be sensitive to optical and/or radio radiation, and, after the development of physics, the idea of electromagnetic radiation for interstellar communication should be a cosmic commonplace—a convergent idea evolving independently on countless worlds throughout the galaxy after the local discovery of elementary astronomy, what we might call the facts of life. If we are fortunate enough to make contact with some of those other beings, I think we will find that much of their biology, psychology, sociology and politics will seem to us stunningly exotic and deeply mysterious. But I suspect we will have little difficulty in understanding each other on the simpler aspects of astronomy, physics, chemistry and perhaps mathematics.”
4.5 stars. The writing here warrants five stars. At 40 years and counting and the fact the book could have been longer, this is more like a 4 star book to me. Cosmos and Pale Blue Dot still remain my favorite Sagan books and are beautiful works. Sagan has long since passed away but I greatly miss his insights and his non-righteous quest for the truth. It really shines through in virtually all of his writing. Highly recommended.