The time scale for evolutionary or genetic change is very long. A characteristic period for the emergence of one advanced species from another is perhaps a hundred thousand years; and very often the difference in behavior between closely related species -say, lions and tigers- do not seem very great... But today we do not have ten million years to wait for the next advance. We live in a time when our world is changing at an unprecedented rate. While the changes are largely of our own making, they cannot be ignored. We must adjust and adapt and control, or we perish.
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About Carl Sagan
Carl Sagan was a 20th-century American scientist and science communicator. Carl Edward Sagan was an American astronomer, planetary scientist and science communicator. Initially an assistant professor at Harvard, Sagan later moved to Cornell, where he was the David Duncan Professor of Astronomy and Space Sciences and directed the Laboratory for Planetary Studies. Read more on Wikipedia →