"The Dragons of Eden" by Carl Sagan


“The Dragons of Eden” (1977) was written by Carl Sagan, an American scientist who specialized in astronomy and the search for extraterrestrial life. Sagan achieved worldwide recognition as an advocate for science education with his television series, Cosmos

He won the Pulitzer Prize for this book and it spent thirty-three weeks on the New York Times bestseller-list. The book offers to explain the evolution of the human species from the beginning of the Big Bang to our current time period. 

Sagan looks at clues from a wide variety of sciences including anthropology, biology, mythology, philosophy, and psychology to support his reasoning. He spends a great deal of the book focusing on the human brain, how it functions, and how it differs from other animals. 

 Carl Sagan achieved worldwide recognition as an advocate for science education with his television series,  Cosmo.

Carl Sagan achieved worldwide recognition as an advocate for science education with his television series, Cosmo.


1) Humans are young, very young 

It is disconcerting to find that in such a cosmic year the Earth does not condense out of interstellar matter until early September; dinosaurs emerge on Christmas Eve; flowers arise on December 28th; and men and women originate at 10:30pm on New Year’s Eve. All of recorded history occupies the last ten seconds of December 31; and the time from the waning of the Middle Ages to the present occupies little more than one second. 
— Page 17

Carl Sagan starts his book by talking about time and the history of the universe. It may be hard to grasp just how old everything in the universe is so Sagan creates a Cosmic Calendar to better comprehend the length of time. He does this by essentially taking the ~14 billion years of time since the Big Bang occurred and scaling it onto a typical 12-month calendar. 

The calendar starts on January 1st, beginning with the Big Bang. May 1st would be the origin of the Milky Way Galaxy, and September 9th would be the origin of the solar system. Around September 25th, life starts to exist on Earth. By December 16th the first worms exist on Earth, and on December 22nd insects exist. Mammals begin to roam Earth by December 26th but it isn’t until December 31st that the first humans can be found on Earth.

However, the calendar gets even more specific. The first humans occur at ~10:30 PM on December 31st. By 11:46 PM, fire is domesticated. By 11:59:20 PM, agriculture is invented. The birth of Christ occurs at 11:59:56 PM, the Renaissance in Europe occurs at 11:59:58 PM, the current time period of man occurs at the first second of New Year’s Day. 

The reason Sagan dives deep into the Cosmic Calendar is that he is trying to show that humans are incredibly new in the scale of the universe. The universe is ~14 billion years old and modern humans have existed for a ridiculously small portion of time. Science and technology can only tell us so much about the past and our ancient ancestors weren’t developed enough to write down their history but Sagan does his best to explain the evolution of mankind through research from a wide range of sciences. 

2) Dragons Are Within & Around Us 

Or does the metaphor of the serpent refer to the use of the aggressive and ritualistic reptilian component of our brain in the further evolution of the neocortex? With one exception, the Genesis account of the temptation by a reptile in Eden is the only instance in the Bible of humans understanding the language of animals. When we feared the dragons, were we fearing a part of ourselves? One way or another, there were dragons in Eden. 
— Page 150

Halfway through the book, Sagan talks about dragons and the meaning behind the book’s title. Although dragons are mythical creatures, there are real animals that resemble dragons, one example is the Komodo dragon–a reptile that can weigh up to 300 pounds and be 10 feet in length (oh and did I mention they are venomous?). 


There's good reason that our ancestors were afraid of these dragon-like creatures. It’s no surprise that there are plenty of myths about dragons and how they terrorized and attacked humans.

Interestingly enough, Sagan points out that dragon myths aren’t just found in the Western world, but are instead a worldwide phenomenon. This may be because of dinosaurs or similar reptiles, which may have resembled dragons.


Dragons might also be a metaphor for the ‘reptile brain’ in humans, which controls our aggression and rituals. Another theory is that perhaps humans fear the dragon inside of themselves and other people.

Sagan also notes that in the story of Genesis, Adam and Eve are tempted by a reptile in Eden. Since a reptile has been the downfall of man once, it’s possible man stays away from reptiles to avoid another mistake such as the one committed by Eve. Either way, dragons can be found inside of people and the outside world. 


3) A Few Other Lessons

Since Sagan’s book is tightly packed with facts and information, here are some of the interesting ideas learned from his book:

  • The best measure of intelligence of an organism is not the mass of the brain, but the ratio of the mass of the brain to the total mass of the organism. 
  • In a diagram of brain mass versus body mass for primates, mammals, birds, fish, reptiles, and dinosaurs, Homo sapiens rank number one while dolphins rank second.
  • Having a large brain compared to our body mass may be one of the reasons humans have been able to survive and rise to the top of the food chain.
  • However, this gift comes with a price. Humans are the only species that experience pain during childbirth, this is due to the large skull of human babies. 
  • Our brain gives us the ability to think about the future and focus on long-term benefits, but we get a lot of anxiety from it and from thinking about our inevitable end.



After reading "The Dragons of Eden", it’s clear to see why this book won a Pulitzer Prize. The book is jam-packed with incredible facts and information that will require readers to take a moment to soak it all in. The book flows wonderfully and has diagrams and images to help readers better understand the text. 

The book is about 250 pages long and expertly written, so it is quite easy to read–no Ph.D. or Masters in science degree is required. However, I do wish this book had clear-cut lessons for readers at the end of each chapter to identify the key information from each chapter. 

Also, since this book was written in 1977, its safe to say that in the past 40 years someone has written a book on this topic with updated information. But, since I have yet to find that book, I’m giving Sagan a curve and ranking his book a four out of five. 

Rating: 4/5 stars


If you're interested in getting this book, click here or on the image below!

  • Book: "The Dragons of Eden" by Carl Sagan
  • Pages: 288
  • For: People interested in learning about the evolution of mankind and the brain
  • Lesson: Gain insight into the brain of man and beast, the origin of human intelligence