Carl Sagan – Our Evolution From “Star Stuff”


Carl Sagan’s description of how we evolved from “Star Stuff” and the journey to go back to our origin – in the Stars.

From Cosmos: A Personal Voyage episode 8, “Journeys in Space and Time”.

The themes of space and time are intertwined. Worlds and stars, like people, are born, live and die. The lifetime of a human being is measured in decades, but the lifetime of a sun is a hundred million times longer. Matter is much older than life. Billions of years before the sun and earth even formed, atoms were being synthesized in the insides of hot stars, and then returned to space when the stars blew themselves up. Newly formed planets were made of this stellar debris. The earth and every living thing are made of star stuff.

But how slowly in our human perspective life evolved, from the molecules of the early oceans, to the first bacteria. The reason evolution is not immediately obvious to everybody is because it moves so slowly and takes so long. How can creatures who live for only 70 years detect events that take 70 million years to unfold, or 4 billion? By the time one-celled animals had evolved, the history of life on earth was half over. Not very far along to us, you might think, but by now almost all of the basic chemistry of life had been established. Forget our human time perspective.

From the point of view of a star, evolution was weaving intricate new patterns from the star stuff on the planet earth, and very rapidly. Most evolutionary lines became extinct. Many lines became stagnant.

If things had gone a little differently, a small change of climate, say, or a new mutation, or the accidental death of a different humble organism, the entire future history of life might have been very different. Perhaps the line to an intelligent, technological species would have passed through worms. Perhaps the present masters of the planet would have had ancestors who were tunicate eggs. We might not have evolved. Someone else, someone very different, would be here now in our stead, maybe pondering their origins.

carl sagan star stuff Carl Sagan   Our Evolution From Star Stuff