When Humans Nearly Vanished

July 9, 2018
Despite the title, the Toba volcano makes not much more than a cameo appearance in this slim volume. Prothero (The Story of Earth in 25 Rocks), a paleontologist and geologist, describes Toba’s eruption on the island of Sumatra in Indonesia, around 74,000 years ago, as the “largest volcanic eruption in the past 28 million years,” and briefly touches on the theory of how it decimated humanity, leading to a population bottleneck that partly explains the relative lack of genetic diversity in humans today. He also touches on the process by which scientists discovered the eruption had ever occurred, which only became apparent with new findings in 1993. The bulk of this book, however, is a primer for related topics: brief summaries of the geology of volcanism, the structure of DNA, the evolutionary relationship between humans and primates, and the fossil evidence for the evolutionary origins of Homo sapiens. Prothero writes clearly and at a level accessible to the lay reader, but he presents no new material and is unlikely to satisfy anyone looking for more than a precis of the current state of knowledge in these diverse fields.

October 1, 2018
About 73,000 years ago, Sumatra's Mount Toba erupted. This supervolcano created an explosion over 1,000 times as powerful as Krakatoa and also, as Prothero writes, might possibly have come very close to wiping out human life on Earth. There is a lot to consider about this controversial argument, and in this slim title, Prothero looks at all of it. He covers current investigations into Toba's fallout, DNA analysis of the genetic-bottleneck theory, which suggests all of humanity can be traced to a small population from about 70,000 years ago, and theories about what humanity looked like at that time. His interests are wide, his sources varied, as he quotes from a long letter by Pliny the Younger, recalls the scientific achievements of Rosalind Franklin, and considers the serendipity of contemporary geological research. Prothero's enthusiasm is infectious, and his boundless curiosity will draw in readers who may have only the lightest of knowledge about volcanoes, especially one as obscure as Toba. Prothero is a valuable guide.(Reprinted with permission of Booklist, copyright 2018, American Library Association.)