Smithsonian Books is releasingWhen Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano, by Donald R. Prothero Oct. 16. Around 74,000 years ago, the dome of Mount Toba, in today’s Sumatra, Indonesia, began to rumble. A deep vibration shook the entire island. Jets of steam and ash emanated, followed by an explosion louder than any sound heard byHomo sapienssince the species evolved on Earth. The eruption of the Toba supervolcano released the energy of a million tons of explosives; 700 cubic miles of magma spewed outward in an explosion 40 times larger than the largest hydrogen bomb and more than a thousand times as powerful as the Krakatau eruption in 1883. So much ash and debris were injected into the stratosphere that they partially blocked the Sun’s radiation and caused global temperatures to drop by 5 to 9 degrees. It took a full decade for Earth to recover to its pre-eruption temperatures.

When Humans Nearly Vanishedexamines the argument that the Toba catastrophe nearly wiped out the human race, leaving only about a thousand to 10,000 breeding pairs of humans worldwide. Human genes today show evidence of a “genetic bottleneck,” an effect seen when a population of organisms becomes so small that their genetic diversity is greatly reduced. This group of survivors could be the ancestors of all humans alive today.

Prothero explores the geological and biological evidence supporting and questioning the Toba bottleneck theory, reveals how the explosion itself was discovered and offers insight into how the world changed afterward and what might happen if such an eruption occurred today.

About the Author

Prothero specializes in physics, planetary sciences, astronomy, earth sciences and vertebrate paleontology. He taught for 35 years at Columbia, Knox, Pierce and Vassar colleges, most recently as professor of geology at Occidental College and as lecturer in geobiology at the California Institute of Technology. He has authored or edited more than 300 scientific papers and 30 books, includingGiants of the Lost World: Dinosaurs and Other Extinct Monsters of South America.

About the Book

Title:When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano
Author: Donald R. Prothero
On-Sale Date: 10/16/18
Price: $27.95 / Pages: 208
ISBN: 978-1-58834-635-3
Smithsonian Books