When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano

by Donald R. Prothero

The fascinating true story of the explosion of the Mount Toba supervolcano--the Earth's largest eruption in the past 28 million years--and its lasting impact on Earth and human evolutionSome 73,000 years ago, the huge 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 from the summit, followed by an explosion louder than any sound heard by Homo sapiens since our species evolved on Earth. The eruption of the Toba supervolcano released the energy of a million tons of explosives; seven hundred cubic miles of magma spewed outward in an explosion forty 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 was injected into the stratosphere that it partially blocked the sun's radiation and caused global temperatures to drop by five to nine degrees. It took a full decade for Earth to recover to its pre-eruption temperatures.When Humans Nearly Vanished presents the controversial argument that the Toba catastrophe nearly wiped out the human race, leaving only about a thousand to ten thousand 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. Donald R. Prothero explores the geological and biological evidence supporting 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. Prothero's riveting account of this calamitous supervolcanic explosion is not to be missed.

Genres: Science, History, Nonfiction, Geology, Audiobook, Biology, Palaeontology

207 pages, Kindle Edition

First published January 1, 2018

About the author

Donald R. Prothero is a Professor of Geology at Occidental College and Lecturer in Geobiology at the California Institute of Technology. He teaches Physical and Historical Geology, Sedimentary Geology, and Paleontology. His specialties are mammalian paleontology and magnetic stratigraphy of the Cenozoic. His current research focuses on the dating of the climatic changes that occurred between 30 and 40 million years ago, using the technique of magnetic stratigraphy. Dr. Prothero has been a Guggenheim and NSF Fellow, a Fellow of the Linnean Society, and in 1991 received the Schuchert Award of the Paleontological Society for outstanding paleontologist under the age of 40, the same award won by the renowned paleontologist Stephen Jay Gould. He has authored or co-edited numerous books, including Horns, Tusks, Hooves and Flippers: The Evolution of Hoofed Mammals, the best-selling textbook from McGraw-Hill, Evolution of the Earth, Evolution: What the Fossils Say & Why it Matters, Bringing Fossils to Life, After the Dinosaurs, and the textbook Sedimentary Geology. He is also a Technical Editor of the Journal of Paleontology.

Reviews

[Montzalee Wittmann · Rating 4 out of 5]

When Humans Nearly Vanished
This was a very good history book documenting what happened and why. I have read several like this but this one was easy to follow.

[Manybooks · Rating 1 out of 5]

So perhaps I should not even be rating Donald R. Prothero's 2018 When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano since I actually only managed to read (or rather to with gritted teeth plow through) about two chapters before giving up due to frustration, anger and also massive and unrelenting boredom. However, since the main reason for my abandonment of When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano has in fact been because I really could no longer abide and stomach Donald R. Prothero's writing style and his frustratingly unfortunate habit of constant name dropping and often veering sharply off topic to wax poetic about his personal scientific icons, I do in fact and strongly believe that I am definitely more than justified rating (and reviewing) When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano without having actually finished it. Because if truth be told, I generally only tend to even consider abandoning books if I really and truly have major issues with them. And yes, by the third chapter, by Land of the Killer Volcanoes I was so massively and all encompassingly annoyed and even furious with the author (and that Donald R. Prothero was basically making us readers almost have to go on a difficult and dragging treasure hunt to discover interesting bits and pieces of scientific knowledge hidden under his increasingly tedious and monotonous hero-worshipping tirades) that for me, not going on with When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano definitely seemed the correct and best, was certainly the least personally stressful way to proceed.

And while I at first was still toying with a low two star rating, the fact that in When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano, Donald R. Prothero provides neither footnotes nor a bibliography, this just has exponentially increased my anger and frustration and has most definitely made me both only consider but one star for When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano and to also not in ANY WAY recommend this book to anyone (as the lack of a bibliography and especially for science-based non fiction is both a total pet peeve and also something that I do in fact consider massively academically suspect and dishonest).

[Mark · Rating 4 out of 5]

The main interest of this book is the bottleneck in the development of the human race and how the eruption of the vulcano Toba in what is now known as Indonesia. The writer has almost one actual chapter on the subject and takes a long road towards the information. I was somewhat disappointed as it was so shortish. However the road towards and around the reason for the bottleneck is certainly informative. The writer certainly wants to put the issue with the almost ending of human lines and various other animals within a larger perspective so the average reader can understand the whole story.

The writer does tell an extensieve story including the ihistory on vulcanos, dna, development of humanity. For somebody new and interested in this subject this book is an excellent start to learn about mankind and natural disasters.
And it is a fairly thin book to read and does not for a lot of knowledge and if you are like me you are left with questions that needs more books. However keep in mind that recent developments in sciences are altering the fields of paleontology, vulcano's, mankind, DNA research into humanity a lot. So reading older books could distord the recent developments. The one I found fascinating was that the extinsion of the dinosaurs is no longer a shut case of a meteor impact but just might have a more difficult answer.
We do live in exciting times.

[Jeanette · Rating 3 out of 5]

This is an excellent non-fiction read. My three star rating is seated in the width of the subject matter. All human history as homo- all volcanic criteria and eons of placements in millions of years of time, dozens of fields of scientific evidence study to core samples and 100's of other minutia to the timings of ash layers etc. So having that wide of a information base to all the 1000's of inputs is no easy read. And also difficult to focus. Very difficult.

And the result is above average to chew the bite it takes. But that doesn't equate to easy tell in the results either. It's extremely dry in tables of facts and charts and associated era fall outs.

But what I liked about it the most was that this book in its wide lens to earth history does begin to define and describe the "bottleneck" syndrome. This occurs for nearly every form of life that has lived on Earth, including homo species. Species have points in time where the genetic material is very limited to and in the numbers of reproducing pairs who will keep the species DNA from extinction. Homo forms past is the entire last quarter of the book and it with proofs brings evidence to such a bottleneck about 74,000 years ago. Many forms of homo became extinct in that era, and just a few forms were left to form the basis for all the DNA we (homo sapiens) now hold.

This isn't a read, IMHO, for the merely curious. It involves much chemical, elemental sciences, and geologic materials language and specification. And it takes a sidetrack to many other volcanic episodes and places on Earth that have initiated bottlenecks and historical evidence. Both.

Most readers who have little knowledge of those Earth Sciences and Forensics of Ancients will have very hard going to grasp all the aspects of this book. I was fairly disappointed at the photos a few times. Black and white and not quite distinct. But overall the whole was well worth the reading for me. It disproves nearly every "ancestor" form of human evolutionary history that I was taught in my youth and mid-life. Both.

[Clif Hostetler · Rating 3 out of 5]

Certain statistical tests performed on DNA sequences can detect historical genetic bottlenecks and how much time has passed since their occurrence. Geneticists from these tests together with the findings of archaeologists have surmised that approximately 74,000 years ago the human population from which we today are descended was reduced to “only about 1,000 to 10,000 breeding pairs.”

Prior to that time humans lived in many parts of the Africa, Europe, and Asia, but they had not yet reached Australia or the Americas. Most of the human population were archaic members of our species, Homo sapiens, however Europe was still dominated by Neanderthals. Due to this broad distribution of human beings it is believed that the population prior to this bottleneck was significantly larger.

It’s interesting to note that DNA variability found in genes of human lice and of our gut bacterium Helicobacter pylori which causes ulcers also experienced bottlenecks at this same time. This sort of bottleneck is also true for other animals including tigers and pandas.

Geologists in their study of the earth’s crust on both land and sea floor have concluded that the largest volcanic eruption in the past 28 million years occurred at about this same time at Mount Toba located in northern Sumatra. The eruption was approximately 1,000 times more powerful than the 1815 Tambora or 1883 Krakatoa volcanos and 3,000 times as powerful as the 1980 Mount Saint Helens eruption. We know the earth’s climate was greatly affected by these more recent eruptions, so we can safely assume that the earth’s climate 74,000 years ago significantly deteriorated for a period of time and was a likely the cause of the population bottlenecks.

To support the above conclusions this book contains much history and scientific information related to volcanos, genetics, human evolution and mass extinctions. This book ends up being a general review of science.

[Beauregard Bottomley · Rating 5 out of 5]

A perfect science book that shows how we think we know about an extinction event while fitting it into our current web of knowledge. No narrative about facts ever stands alone and science is the best narrative that we currently have to explain the web of facts and science theories need context, relations, relevance, and best explanations to be meaningful, and this book provides that.

Darwin wrote the perfect book when he wrote his ‘Origin of Species’ and as this author points out Darwin attacked the problem of evolution from five different perspectives, this book uses five different perspectives while defending its thesis and Darwin also gave the best-known possible arguments against his theory, and this book does too.

As the author writes this book defending his theory, he educates the reader on all of the myriad pieces that fit together and explains the context, relation and relevant science, and even gives the best contra-arguments against his own theory while showing why they are deficient.

This book hooked me from the first page since he kept throwing facts at me and then reasonable narratives explaining the facts. The fact of the matter is that no good scientific explanation stands isolated from the world and the more different perspectives that support it the more ingrained it becomes with our best current scientific truths therefore giving the theory a firmer foundation, but through that foundation building a whole lot of interesting science gets revealed in the process. That’s why this book is one of the best because the author ties a heap of science together while ultimately convincingly defending his thesis.

This book is available in audio format from Scribd.

[Marty · Rating 2 out of 5]

Enjoyed the premise of this book and the discussion of how all the relevant pieces were established, such as the DNA bottleneck and its age, the size and estimated effects of huge, prehistoric volcanoes, etc. However...
It seemed to me that a number of the modern numbers he quoted for comparisons were way, way off. Either that or written in such a way that I didn't grasp what he meant to say even after several re-readings. Did he really mean to say there have been 117, 000 deaths due to accidents (including auto accidents) in the last 34 years? That's how I read it, but at 30,000 to 40,000 deaths in auto accidents annually in the US over that period 117,000 seems like it's off by at least an order of magnitude. And he says or implies that the largest atomic bomb ever built was equivalent 1,000,000 tons of TNT. The "Tsar Bomba" is now rated at about 50,000,000 tons of TNT.
While those aren't really central to the thesis, it makes me wonder how well written and edited the book was and question the comparisons to those numbers that seem really far off.

[Matthew Ochal · Rating 3 out of 5]

The book basically takes a very long way of explaining that “70000 years ago human beings were almost wiped out and this is exactly why we know. And also this is why we know what that means, and the history of how we found out what that means.” Interesting, but a lot of the background felt really unnecessary. Like, I dont really need to know the history of the guy who invented microwaves in order to appreciate how close humans got to being wiped out. But of course, this book is short already, if you got rid of this type of background you wouldnt have a book.

[Keith · Rating 3 out of 5]

I guess this is a classic case of the book not living up to the title. I checked out this book to read about the Toba eruption and the postulated genetic bottleneck in the human experience whereby all living humans trace their lineage back to a small group that existed some 70,000 years ago.

Great. I rub my hands together and .... nothing. The prologue and first chapter speaks of Toba and then he takes off and answer questions that we were not asking in this book. We find out about other volcanoes (Krakatau and Tambora, and Vesuvius). We are told how volcanoes work. We find out about DNA (all the way back to Watson and Crick), we learn about the evolution of man and the peopling of the world. Only in the 7th chapter does the author seem to remember his task ... Toba and the genetic bottleneck. After that, he wanders off on mass extinctions, and speaks of more volcanoes.

At the end of the book, I was irritated for one of two reasons ... either there is not much evidence of the bottleneck or the author just wandered off on different subjects. I'm thinking the latter as he states in Chapter 7 "much as been said and written about the Toba catastrophe ... and we cannot summarize all of the discussion even a book like this one." I find that statement perplexing, because he talked about everything EXCEPT the Toba eruption.

2 1/2 stars.

[Dan Ust · Rating 4 out of 5]

Probably more a 3.5 than a 4.... Overall, decent and easy to read until he gets to rattling off hominin species. Then there’s a huge mess which even the diagrams don’t help. To be sure, human evolution is messy and keeps getting revised. But more diagrams and trimming down that part of the story would’ve been better. After all, he only needs to focus on the humans before and after the Toba eruption — not go into much detail about the history of discoveries regarding Australopithecus and all that.

Another wider point: more maps and diagrams would help. Also, making them more consistent with the text. For instance, there’s a great chart of various eruptions comparing the volumes ejected against the volcano, but it shows volcanoes not mentioned in the text and leaves out many that are mentioned. What effort would’ve been involved in being more inclusive here?

Nevertheless, he does a good job in the beginning going over the detective work to uncover the Toba eruption and all its implications. Living close to several volcanoes (on a good day I can see three of the sleeping giants), I’m an easy sell on a book like this.

[John Kaufmann · Rating 3 out of 5]

This book is mostly about the bottleneck of the human population caused by a major volcanic event some 74,000 years ago, as revealed by fossil evidence and DNA. The first chapter deals with how they found the geologic evidence for the explosion of Mt. Toba. The rest of the book deals with evidence of a bottleneck in human evidence around the same time, pointing to the conclusion that the explosion of Toba caused the bottleneck. A very interesting read, though perhaps at times too detailed on the fossil evidence for my taste/knowledge level.

[Bill Leach · Rating 5 out of 5]

Prothero shows how research in the fields of volcanism and genetics suggest that humans went through an evolutionary bottleneck due to the climatic effects of the eruption of Mount Toba some 74,000 years ago. This idea is detailed in chapter 7 - "Humanity at the Crossroads". Most of the book is devoted to overviews of volcanism and the evolution of man, both summaries being very good.

Chapter 1 - "Mystery of the Missing Megavolcano" - The timing and consequences of the Eruption of Mount Toba in SE Asia have become better known with recent research. Analysis of the Greenland Ice Sheet Project 2 cores by Greg Zielinski has showed that 74,000 years ago the earth's sulphur dioxide level was 25 times higher than today. M. R. Rampino, examining ocean sediment cores, noticed planktonic microfossils showed a 5 to 6 degree C temperature drop at 74,000 years ago, as well as an ash layer at that time. Examination of U-238 decay tracks in the ash particles gave the age as 74,000 years. The chemistry of the ash was found to be hat of Mt. Toba.

Chapter 2 - "Vulcan's Fury" - The author provides accounts of the eruptions of Vesuvius and mount Pelee in Martinique. Lavas like those in Hawaii or Iceland form when hot plumes of magma rise up from the earth’s mantle. These mantle-derived magmas are rich in elements such as magnesium and iron, and the resulting black rocks that form after the lava has cooled are called basalt. Magnesium and iron-rich magmas melt at very high temperatures - they are not only very hot but also very fluid. They erupt as lava that flows along the landscape with the viscosity of water.

At the other extreme are magmas that are richer in silicon, aluminum, sodium, and potassium which melt at lower temperatures than basaltic minerals. Depending on their exact chemistry, these magmas are known as andesites (after the Andes Mountains), dacites, or rhyolites. They tend to be very viscous. In the case of rhyolite, they are too thick and viscous to generate any lava flows at all. Instead, these magmas plug their volcanoes until so much pressure builds up underneath them that eventually the top of the mountain simply explodes. These explosions produce the wide range of shattered volcanic rock known as pyroclastics, which range in size from tiny glass shards of volcanic ash to the pebble-size pieces of pumice known as lapilli. The largest eruptive materials, cobble and boulder-size blobs of magma that cool as they fly through the air, are appropriately known as volcanic bombs. Andesite, dacite, and rhyolite magmas begin as basaltic magma but are transformed into entirely new chemical compositions in subduction zones: places where one tectonic plate plunges under another.

Chapter 3 - "Land of the Killer Volcanos" - Prothero looks at Indonesia and volcanoes in that area, providing accounts of the eruptions of Krakatoa and Tombora. He extends these to the concept of super-volcanoes. The Toba eruption delivered about 3,000 cubic kilometres of ejecta, including hundreds of cubic kilometres of ash and more than 41 cubic kilometres of pyroclastic debris, weighing about ten billion tonnes.

Chapter 4 - "Clues in Your Genes" - A history of the discovery of the structure of DNA by Watson and Crick is provided, and the ideas of the molecular clock and genetic bottlenecks are introduced. Humans passed through a bottleneck about 70,000 years ago.

Chapter 5 - "Roots" - The author tells the stories of some of the earliest discoveries of early humans including Neanderthal specimens in the 1850's, Java man in the 1890's and the fraudulent “Piltdown man” in 1912.

Chapter 6 - "Out of Africa" - Prothero provides an excellent overview of our current understanding of the evolution of modern man.

Chapter 7 - "Humanity at the Crossroads" - The ice age that began about 74,000 years ago did not come to an end until 17,000 years ago, when the earth entered an interglacial period that lasted 10,000 years and resulted in an explosion of human civilization. Anatomically modern humans did not live outside Africa or the Near East until sometime after the Toba eruption. "Bottlenecks everywhere:" - genetic bottlenecks have been found in cheetahs, giant pandas, gorillas and even the bacteria Helicobacter pylori. Almost every organism whose DNA has been sequenced and that had ancestors in Eurasia about 70,000 years ago appears to show the same phenomenon: a population bottleneck about 70,000 years ago, followed by a population expansion about 50,000 years ago. Two lineages of man died out at that time: H. erectus and H. floresiensis. The hypothesis is that the climatic event that was triggered by the Toba eruption 74,000 years ago almost caused the extinction of many animals including modern man.

Chapter 8 - "Volcanoes of Doom" - Looking at he major extinctions, it is clear that only one of the Big Five is related to evidence of an impact of an asteroid or other planetary body. Severe climate change (especially rapid global cooling) seems to have driven two others. But the three remaining of the Big Five are associated with the biggest volcanic eruptions in earth’s history. If there is any single event that is a species killer, it seems to be a gigantic volcanic eruption.

Scientific opinion on the cause of the K-T extinction is moving away from the impact hypothesis and back toward more prolonged volcanic effects associated with the Deccan Traps. It is thought that the end-Permian or P-T extinction was due to volcanism from the Siberian Traps. Recent research has suggested that the cause of the T-J extinction was huge eruptions of the Central Atlantic magmatic province (CAMP) lavas, which occurred when the Atlantic basin ripped apart as Pangaea broke up.

Chapter 9 - "Future Shocks" - The author asks " could it happen again?". He examines large eruptions in the U.S. including Mount St. Helens (1980) and Mount Lassen (1915). Mount Rainier which looms over the Seattle-Tacoma area has not had a major eruption for 5600 years, although minor eruptions occurred in the 1800's. He then looks at past super-volcanos around the world. "It is beyond dispute that some gigantic event changed global climate around the time that Toba erupted, about 74,000 years ago. It is also clear that there was a giant human population crash and bottleneck at the same time."

An excellent book. The piece that was missing is that of the animals that did not make it through the bottleneck, although the loss of human lineages is described. Surely there are many that went extinct during that cooling, and their demise should be apparent today.

[Susan Olesen · Rating 3 out of 5]

Not sure how to rate this book.

I enjoyed it. I truly did. But I'm not sure if it ever found its purpose.

Prothero postulates that the entire planet hit a bottleneck 74,000 years ago, with evidence among a multitude of species, including man. This all happened - as evidenced in numerous places around the globe - about the same time as a catastrophic eruption of Mount Toba in the Phillipines, blanketing the earth with a 1,000-year span of cold and distrupted weather. Mankind could have dipped as low as several thousand breeding pairs.

While this is fascinating, Prothero builds his very brief case by going over paleogeology, paleoanthropology, and just about every possible tie-in science to make sure you understand exactly why he makes this statement. And that's all the book really does, is make a (very convincing) statement.

I have only two points where I would love to speak to him on: If Neanderthals were not of the same species as humans, but so similar they could interbreed (23 & Me says I have more Neanderthal DNA than 86% of respondents, which my flat feet and fat layer will agree with), how can they be different species? Men and Chimps cannot interbreed, but are 99% the same genetically. Cats and Bobcats can't interbreed. Mules and Horses, Horses and Zebras can interbreed, but their offspring are sterile. So how could N. and humans interbreed if they are separate species? I need more information on this.

Also, instead of arguing that the asteroid that allegedly killed the dinosaurs may not have, but a crack in the mantle plates may have - at around the same time - could it not be viable that the impact of the asteroid put such geologic force into motion that it *caused* the crack, *compounding* the incident and thus wrecking greater havoc together?

But overall, an enjoyable, informative, quick read that goes out of its way to make things presentable and understandable without too much scientific jargon. Definitely worth a read.

[Gregory Eakins · Rating 3 out of 5]

When Humans Nearly Vanished details the theory that modern humans experienced a genetic bottleneck somewhere around 70,000 years ago due to the eruption of the Toba volcano in Indonesia.

While I knew that humans are genetically less diverse than they should be as a species had we an uninhibited reproductive timeline, the Toba eruption bottleneck is a new one to me. Other discoveries such as the "Mitochondrial Eve" demonstrate that our ancestors had to deal with many species-changing events throughout our timeline.

Prothero provides a good amount of converging evidence for the Toba event from various sources, which is what good science looks like, but at the same time, he veers off onto a huge number of tangents that are mostly irrelevant to the subject of this book. He wanders all over the place - from volcanoes, to Watson, Crick, and Rosalind Franklin, to chimpanzees to the spread of early humans, and any number of other loosely related controversies. These topics are all covered far better in other books.

The idea that a volcanic eruption almost wiped out our species is interesting enough that this book is worth a look, even if it's a bit of a rambling mess.

[Douglas Summers-Stay · Rating 3 out of 5]

The author believes that when the Toba volcano erupted 74,000 years ago, it caused the bottleneck in human population (reduced to only a few thousand individuals) that also occurred 74,000 years ago. It seems a plausible enough hypothesis, but I think the jury is still out on it. As I was reading I thought, wouldn't there also have to have been a bottleneck in other large mammal species at the same time, if the hypothesis is true? And in fact there was such a bottleneck in many species, which I felt was pretty convincing (since I had thought of the objection before he brought up the evidence.)
The most interesting part of the book to me was the first-hand accounts of major eruptions in history, like Pompeii, Krakatoa, and Tambora (associated with the year without a summer, 1816). There was a discussion of the discovery of DNA, the discovery of Australopithecus and other human ancestors, and other topics which I already was very familiar with so found less interesting. The most relevant was the discussion of mitochondrial eve.

[Pat · Rating 5 out of 5]

Just what I was looking for: a short, general summary of the most recent findings on human evolution and on the major extinctions the earth has experienced. The book is at least half about volcanoes 🌋 and the other half on the latest thinking regarding human evolution. Just a good general overview. I’m buying a copy for reference. So glad my dear public library had this where it caught my eye in “new releases”.

[Daniel Farabaugh · Rating 1 out of 5]

This book is supposed to be about the Toba eruption but unfortunately barely talks about it. Instead, it is a general history of each facet of that explosion. It explains the impact of other massive volcanoes, the process of genetic bottlenecks, etc. It reads like a textbook for those topics. The only saving grace is that it was short and the writing was good.

[Steve · Rating 4 out of 5]

"When Humans Nearly Vanished" by Donald R. Prothero is a fascinating book that delves into the various instances in which humans nearly faced extinction. The book takes readers on a journey through time, covering events from as far back as the Ice Age to as recent as the present day. Prothero's writing is engaging, informative, and accessible to both experts and non-experts alike.

One of the book's main themes is the fragility of human existence. Prothero highlights the many ways in which humans have come close to extinction, including natural disasters, pandemics, climate change, and human conflict. He provides a detailed analysis of each event, explaining how it happened, its impact on human populations, and what lessons can be learned from it.

For example, Prothero discusses the Toba supervolcano eruption that occurred approximately 74,000 years ago. This event is thought to have caused a volcanic winter that lasted for several years, leading to a significant decline in global temperatures and a decrease in food resources for humans. Some estimates suggest that the human population was reduced to as few as 3,000 individuals. Prothero explains how humans managed to survive this catastrophic event and how it affected their subsequent migration patterns.

Another significant event covered in the book is the Black Death pandemic that swept through Europe in the 14th century. Prothero describes how the disease killed millions of people and fundamentally changed the social and economic structures of European society. He also explores how the pandemic influenced the development of modern medicine and public health.

Prothero also discusses more recent events, such as the nuclear accidents at Chernobyl and Fukushima. He explains how these events have had long-lasting impacts on human health and the environment, and he examines the ways in which humans have attempted to mitigate their effects.

One of the book's strengths is the way in which Prothero ties these events together to provide a broader perspective on human history. He demonstrates how humans have been shaped by their environment and how they have had to adapt to changing circumstances in order to survive. He also explores the ways in which human actions have contributed to their own vulnerability, such as the role of deforestation and climate change in exacerbating natural disasters.

Overall, "When Humans Nearly Vanished" is a highly informative and engaging book that provides a comprehensive overview of the many ways in which humans have come close to extinction throughout history. Prothero's writing is clear and accessible, and his expertise in paleontology and geology shines through in his analysis of these events. The book is highly recommended for anyone interested in human history, climate change, or natural disasters.

[Steven Rowley · Rating 4 out of 5]

The study of volcanoes fascinates me, and I expected this book to focus on the impacts of the recently discovered Toba eruption of 74,000 years ago. Instead, I was treated to a wealth of interdisciplinary evidence to support the central thesis that this event cooled Earth and almost caused human extinction. I enjoyed the narrative and learned a great deal about multiple, overlapping fields of science and the scientific method. However, the book "wandered off" at times; for example, the story devoted more time to summarizing complex human evolution than to describing the Toba event. This level of detail is necessary for a journal article but probably detracted from the main topic of this less technical summary. Nevertheless, I recommend this book.

[Paige McLoughlin · Rating 5 out of 5]

73000 years ago the Toba supervolcano nearly wiped out humanity and other species. The book explores the history of all the scientific threads that came together to weave this picture that explained a human bottleneck from this eruption and how humanity radiated out of this cataclysm. Very good takes in elements of geology, biology, genetics, physics. Covers other mass extinctions and explains some of the major changes in earth's history and how we came to know about these changes. Very good book for a short 200 page read.

[Aaron · Rating 3 out of 5]

The well written and informative writing style in this book more than makes up for the somewhat vague and meandering thrust of the narrative. This book was less about the Toba eruption specifically and more about volcanism and human evolution in general than I would have liked but it was still compelling and I definitely learned something.

[Peter Bradley · Rating 3 out of 5]

When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano by Donald R. Prothero


Deep time is intimidating. We have had maybe five thousand years of recorded history, but human existence goes back forty times that length. What happened during that long “dark age”? With genetics and a half dozen unrelated disciplines, we are throwing a little light on the darkness, but it is akin to a match lighting up a football field at night after the lights have been turned off.

This book by Donald Prothero outlines the surprising discovery of evidence that the human race nearly went extinct approximately eighty thousand years ago. Telling this story involves covering a range of recently developed scientific disciplines and their equally recent discoveries. Prothero employs the concept of “consilience” to explain how discoveries in widely disparate disciplines can converge to reveal a common truth.

The chief discovery was evidence of ash layers from various points across the world, indicating that a mega-volcano, Mt. Toba, had exploded at some time in the deep past, approximately 74,000 years ago. This volcanic explosion dwarfed anything in recorded history. As Prothero explains:

This was the state of things as that fatal day about 74,000 years ago dawned. Events really got rolling when the huge dome rumbled with a deep vibration that shook all of Sumatra. Jets of steam and ash shot one after another from the summit. Then came an explosion louder than any sound previously heard by humans in their entire evolution. For comparison, when the Krakatau (or Krakatoa) volcano, also in Indonesia, erupted in 1883, it created a sonic boom that could be heard 8,000 kilometers (5,000 mi) away and which traveled around the world seven times. That blast, 5,000 times as powerful as the Hiroshima nuclear bomb explosion, was the largest explosion heard in recent times. Yet the eruption of Mount Toba released the energy of a million tons of explosives, 40 times larger than the largest hydrogen bomb that humans have ever built, more than 1,000 times as powerful as Krakatau, and 3,000 times as powerful as the eruption of Mount Saint Helens in 1980. Thus, the sonic boom from Toba must have been deafening to animals and people for many kilometers around and must have bounced around the earth repeatedly, dwarfing any other sound produced on earth in the previous 28 million years.

Prothero, Donald R.. When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano (pp. 2-3). Smithsonian. Kindle Edition.

The effect of this explosion was catastrophic for global weather patterns. The ash cover would have blocked sunlight for years. When Krakatoa erupted in 1883, global temperatures dropped about 2 to 4 degrees Fahrenheit for more than a year. The spectacular orange-red sunsets in Europe may have been the inspiration for Edvard Munch’s “The Scream.” (1893.) The Mt. Tambora explosion in 1815 injected so much dust into the stratosphere that it led to the famous “year without a summer” as the ash blocked sunlight, resulting in crop failures and the spread of disease.

The Toba explosion was far worse:

The eruption of Toba about 74,000 years ago was 1,000 times as large as that of Tambora or Krakatau. It didn’t just trigger a summerless year or a short cold spell spanning several years: global temperatures dropped by 3° to 5°C (5° to 9°F), to a worldwide average of just 15°C (60°F) after three years, and took a full decade to recover to pre-eruption levels. The tree line and the snow line fell to 3,000 meters (10,000 ft) lower than where they are today, making most high elevations uninhabitable. Ice cores from Greenland show the evidence of this dramatic cooling in trapped ash and ancient air bubbles.

Prothero, Donald R.. When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano (p. 5). Smithsonian. Kindle Edition.

Multiple lines of evidence indicate that the Earth experienced a dramatic cooling event approximately 74,000 years ago, including stalactite formations in New Mexico and ice samples from Greenland. The Toba eruption was also timed to coincide with an ice age that began approximately 74,000 years ago and lasted until around 17,000 years ago.

Another line of evidence came from population genetics. Prothero explains how scientists use DNA to determine mutation rates, which provides a kind of genetic clock for the past. This information can be used to determine population size at various times in the deep past. The Toba explosion may have been catastrophic for the human race, which was reduced to around 1,000 to 10,000 human breeding pairs worldwide.

The connection is circumstantial. The evidence points to an explosion of Toba around 74,000 years ago, and the evidence points to this bottleneck in humans and other species around the same time:

What happened to people and animals during this terrible time? As we shall see in the rest of this book, many geneticists and archaeologists believe that the Toba catastrophe nearly wiped out the human race; afterward, they argue, only about 1,000 to 10,000 breeding pairs of people survived worldwide. Supporting this idea are both geologic evidence of Toba’s size and atmospheric effects and indications of a human genetic bottleneck that happened around the time of the eruption. A genetic bottleneck occurs when the number of individuals in a population drops so low that its genetic diversity is greatly reduced, and all descendants of that population carry the rare genes of the handful of survivors.

Several studies have found similarly timed bottlenecks in the genes of human lice and of our gut bacterium Helicobacter pylori, which causes ulcers; according to these organisms’ molecular clocks, which show how much time has passed since a genetic change took place, both bottlenecks date back to the time of Toba. The molecular clocks of a number of other animals, including tigers and pandas, indicate that they, too, passed through a bottleneck around that time. In short, Toba was the biggest eruption since modern humans appeared on earth, and it came very close to wiping out people, along with many other animals, altogether.

Prothero, Donald R.. When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano (p. 5). Smithsonian. Kindle Edition.

However, while this is a fascinating thesis, some reservation is required. The dating of the bottleneck is not exact:

So when did humans go through that bottleneck? The latest evidence gathered from dated archaeological sites places it at least 48,000 years ago, which is a bare minimum: there are not a lot of archaeological sites known from 48,000 or more years ago, so the bottleneck could have happened much earlier. But based on the age of dated archaeological sites and modern Homo sapiens fossils, we can use the molecular clock to get a minimum estimate for how long ago all the humans on the planet diverged from a small survivor population. Some recent genetic studies place this divergence around 70,000 years ago. Hmm: 70,000 years ago. What else was happening at that time?

Prothero, Donald R.. When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano (pp. 92-93). Smithsonian. Kindle Edition.

At 74,000 years ago, modern humans were confined to Africa (if the “Out of Africa” theory is valid.) A cooling event that disrupted the ecology of Africa at that time might have been more severe than one that occurred after humans had expanded beyond Africa.

So, what happened? And when did it happen? It’s not entirely clear, although Prothero puts all the chips on the Toba eruption.

Prothero offers an interesting explanation for why mass extinctions seem to happen every 28 million years (approximately):

Finally, in 1990, the paleontologist Steven Stanley showed why mass extinctions tended to be spaced roughly (but not exactly) 26 million years apart and don’t happen more often. After a truly giant mass extinction, so much of life’s diversity vanishes that for about 5 to 10 million years, most of the extant species are descendants of the extinction-resistant survivors. These species tend to be opportunistic, hardy generalists that can live almost anywhere and recover quickly, just as weeds do a few days after you finish gardening. It takes a minimum of 20 million years for highly specialized species that are vulnerable to extreme environmental conditions to evolve and reoccupy the old niches. Thus, a major mass extinction can’t happen fewer than 20 to 26 million years after a previous mass extinction.

Prothero, Donald R.. When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano (pp. 157-158). Smithsonian. Kindle Edition.

This book spends a great deal of time on the science of the subject. The reader gets a lot of information on volcanology and geology. There is quite a bit on human evolution, including hominids before homo sapien, going back to the Ramapithicus, Lucy, and the famous hoaxes. Much of this appears to be far beyond the scope of the brief necessary for the Toba eruption. Prothero offers a good survey of the molecular chemistry behind using DNA to date changes in the human genome. However, I am still unsure how a statistically steady rate of mutations in the human genome can be used to show or date a population bottleneck.

The story is interesting. It reminds us that humans are not in control of the world, that we are at the mercy of powers beyond our imagination. Our being here was not foreordained in anything but the theological sense. If things had gone differently, there might not be an intelligent species to fathom the mysteries of deep time.

[Claudia · Rating 2 out of 5]

Perhaps I was expecting too much but I certainly didn't expect a book regarding the Toba volcanic eruption ~74,000 years ago to basically be done talking about it a third of the way through.

There was talk about drilling for ice cores as well as sea sediment core and what scientists use them for - air bubbles frozen in the ice can tell about what the atmosphere and even weather was like: gases, ash particles from eruptions near and far, pollen, greenhouse gases - while sea sediments collect dust and ash, dead marine animals as well as plankton which can indicate population explosions or die-offs as well as acidification of the oceans. So thicker bands of ash can indicate the source was closer while carbon dating of creatures before and after the band as well as the air in the ice cores can basically convey an idea of when.

So evidence collected says there was a massive eruption of the Toba volcano in Sumatra, Indonesia and based on other - more recent eruptions like Tambora and Krakatau - scientists can closely estimate how much gas and material was ejected into the air.

Then we start veering off. History of the discovery of DNA and it's construction. How much 'junk' DNA - genes that basically aren't used anymore or are duplicates. Comparison of the human genome with other animals from great apes to kangaroos. How various changes can indicate how far back on the genetic tree two species split off. Mitochondrial DNA which is transferred through the female and eventually showed the human population suffered a bottleneck in genetic diversity about 70,000 years ago. That all samples collected and tested - seemed like a rather limited selection although it was across the world - bring the trail back to a
primeval 'Eve' which nearly all humanity has as their 'first' mom.

Then we're off to evolution and genetics and the search for humanity's ancestors and fossils of hominids. The first and second wave of human migration out of Africa. The five major extinction events and what scientists saw caused them. A bit about the supervolcanoes - mostly the three major eruptions in the U.S. - Colorado's La Garita and two Yellowstone - verses Mount St. Helens' performance in 1980 along with where a couple more supervolcanoes are.

And we're done! I understand giving the reader additional information to back up how the bottleneck was discovered - other species were found to have a similar restriction about the same time, even some bacteria in human stomachs. Along with finding the cause of the thick layers of ash in some deep sea cores. And how these situations lead to a possible concurrence.

I just expected more on Toba and the correlation to human die-off. Not the genetics, evolution and paleoarcheology.

2021-108

[Maynard Handley · Rating 2 out of 5]

It's not a BAD book, much better than most books to which I give two stars.
My main problem with it is that it's really a magazine article expanded to a book. The expansion takes to form of including large amounts of background material (geology, biology, paleoanthropology) that, maybe I'm being snooty, but should be known to any intelligent reader.

Or to put it differently, it's a fine book for a smart young teen, but I can't see who the target audience is among adults. The population that want to read a book like this, but don't already know all the preliminary material that takes up 80% of the pages, must be minuscule.

[Thomas Ray · Rating 4 out of 5]

When humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano, Donald R. Prothero, 2018, 198 pages, ISBN 9781588346353, Dewey 551.210959812

The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" but "That's funny."--Isaac Asimov, 1987. p. 7.

Current atmospheric carbon dioxide, 410 parts per million, is the highest in 50 million years. p. 13.

PREHISTORY

Humans diverged from chimps 5 million to 7 million years ago. p. 103.

Australopithecines lived from 4 million to 2 million years ago. pp. 91, 122-129.

Homo erectus left Africa 1.8 million years ago. p. 130. Or 1 million years ago p. 142.

Neanderthals diverged from Homo sapiens 588,000 years ago p. 88 or 300,000 years ago p. 141. [but remained able to interbreed--still the same species].

Homo sapiens appeared in southern Africa 100,000 to 300,000 years ago. pp. 1, 141. Or 1.2 million years ago p. 131.

Y-CHROMOSOME ADAM

All human Y chromosomes descend from one African man who lived 200,00 to 300,000 years ago. p. 88.

MITOCHONDRIAL EVE

All human mitochondrial DNA comes from a woman who lived in Africa between 140,000 and 200,000 years ago. p. 86.

TOBA CATASTROPHE

About 74,000 years ago: Humans lived in Africa, Asia, and Europe, but not Australia nor the Americas. p. 1.

Mount Toba (in northwestern Sumatra, Indonesia, west of Malaysia, northwest of Singapore) erupted: the largest eruption in 28 million years. pp. 2, 6, 48. It spewed 720 cubic miles of ash into the atmosphere. p. 4. Global air temperatures fell 5°F to 9°F; it took 10 years to rewarm. p. 5. Or began a 1,000-year or 57,000-year ice age p. 147. The tree line and snow line descended 10,000 vertical feet. pp. 5, 146-147.

VOLCANIC EXPLOSIVITY INDEX pp. 47-49

VEI 
0-1 most Hawaiian flows
 4 Pelée (Martinique) 1902, > 0.1 km³ or 0.024 mi³
 5 Mount Saint Helens (Washington) 1980, 1 km³ or 0.24 mi³ 
 5 Vesuvius (Italy) 79 CE, > 1 km³ or 0.24 mi³ 
5-6 Pinatubo (Philippines) 1991, 5 to 10 km³ or 1.2 to 2.4 mi³
 6 Krakatau (Indonesia) 1883, 20 km³ or 4.8 mi³. Global air temperatures fell 1°C to 2°C, stayed low for 5 years.
 7 Tambora (Indonesia) 1815, > 100 km³ or 24 mi³. Largest in recorded history p. 59. Sulfuric acid and fine ash stayed in the atmosphere for several years. 1816 no summer. Global average air temperature fell 0.7°C. p. 61. Crop failures caused a European famine. p. 63.
 8 Yellowstone (Idaho, Montana, Wyoming) 640,000 years ago, 1,000 km³ or 240 mi³ pp. 178-179.
 8 Toba (Indonesia) 74,000 years ago, 3,000 km³ or 720 mi³
 8 La Garita (Colorado) 27.8 million years ago, 5,000 km³ or 1,300 mi³ p. 177.

EFFECTS

Only about 5,000 people survived to have now-living descendents. pp. 5, 91.

Several other large-animal species also suffered genetic bottlenecks at about that time. pp. 144-145.

All humans on Earth (except a few of the still-surviving ancient African lineages) are extremely closely-related. p. 183. [?? There are more than a few people in Africa, and everyone's lineage is equally ancient.]

OUT-OF-AFRICA II

Ancestors of native peoples in Eurasia and the Americas left Africa 71,000 to 77,000 years ago. They reached Europe 55,000 years ago, Australia 50,000 years ago, the Americas 13,000 to 16,000, or maybe 30,000, years ago. All living Native Americans descend from 70 individuals who lived 11,000 to 13,000 years ago. pp. 88-89, 91.

HOW WE KNOW

Sulfur dioxide in bubbles trapped in ice from 74,000 years ago was off the scale. p. 14.

Water containing oxygen-16 evaporates more readily than water containing oxygen-18. Polar ice thus has mostly the lighter oxygen isotope. The more polar ice, the higher the oxygen-18 concentration in seawater, and thus in shells of zooplankton in sediments. Minerals in 74,000-year-old sediments had enough oxygen-18 to indicate global air temperatures more than 10°F cooler in just a few hundred years. There was ash at that layer too. pp. 19-20, 148.

UGLY SPIN

Published by Smithsonian Books. Brought to us by our friends the U.S. Government. With a friendly reminder that U.S. military spending is a Good Thing! We let geologists sample the ice we drilled, trying to hide nuclear missiles in Greenland glaciers.

The author is a geologist and a military buff. pp. 14-15, 36.

ERRORS

All human mitochondrial DNA comes from a woman who lived between 140,000 and 200,000 years ago. "In other words, most human fossils more than 200,000 years old are not closely related to anyone living today." p. 86. No, they could be Eve's ancestors.

"All modern humans descend from African ancestors who left that continent less than 100,000 years ago." pp. 87, 183. No, modern Africans descend from African ancestors who never left that continent.

"All of us descend from a common ancestor who left Africa less than 70,000 years ago." p. 183. He had said that we [non-Africans] descend from a /population/ that left around that time. This wording contradicts what he said earlier about Adam and Eve.

Gives metric and English measurements for everything--which often contradict each other: sloppy number-work.

Claims 200,000 dead in 1816-1817 was the worst European famine of the 19th Century, p. 63. To the contrary, 1.1 million Irish starved to death in 1845 and 1846. --Revolutionary Spring: Europe Aflame and the Fight for a New World, 1848-1849, Christopher Clark, 2023, pp. 44-45.

[Elmwoodblues · Rating 2 out of 5]

Donald Prothero writes like the scientist he is: precise (you get metric measurements, then standard, for everything, every time), attributable data; charts and graphs; and dry, non-sensational prose. I wasn't expecting Jurassic Park or Raquel Welch in a fur bikini, but the 'Human' part of the title seemed scant. Very volcanism- and geology-forward, with a backup of genetic sciences, so maybe that was where he lost my interest. YMMV.

[Tara Ravi · Rating 1 out of 5]

Homeskillet got so into talking about the history of molecular biology that he forgot to mention the volcano

[CarolBeth · Rating 2 out of 5]

OOOOKAY…you know one of those books that you finish just by sheer force of will? The kind that you’re really glad is only 183 pages long? The kind you aren’t even REMOTELY interested in reading the acknowledgements? I’ve just finished one like that. Sigh. I have finished, with great relief, “When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano” by Donald R. Prothero. Note: I feel really SMART that I finished it.

I found this book when I read a scientific article about the Toba Volcano eruption, some 74,000 (more or less) years ago. I found the article interesting, and it raised some questions. First, let me tell you, “Dagnabit! I’m a MUSICIAN, not a SCIENTIST, Jim!” However, I do roam around outside my musical world quite often, and usually can understand things.

Here’s the promise (from the blurb): “The fascinating true story of the explosion of the Mount Toba supervolcano—earth’s largest volcanic eruption in the past 28 million years – and its lasting impact on both the planet and human evolution.”

The first chapter explores Toba and its effects. Then the author switches over to a description of more recent volcanic eruptions and what we can learn from them. He talks about the genetic bottleneck, but swiftly veers into a fairly deep discussion of the people that discovered the double-helix structure of the DNA, and who should have gotten credit for that, and why they didn’t, and…and…and…never quite gets back to the discussion of the genetic bottleneck which is part of the proof of Toba’s existence. Then we get into all the different fossil evidence for different types of humanoid creatures, and the ones that were fake, and…and…and…

I took deep exception to his repeated inference that people with spiritual beliefs were deluded, with statements like “In the decades since Huxley’s book appeared, nearly everyone without religious blinders about humanity has learned to get past the image of screeching apes and see their humanlike features.”

I did find fascinating the historical accounts of Pompeii, among other ancient volcanic eruptions. I was unaware that Pliny the Younger had experienced and written about the Pompeii eruption. I also enjoyed the author’s assertion that we are all one race; I totally agree with that. However, this book should have had references, footnotes.

The promise of the book was barely and very thinly fulfilled. It could be that this book would be valuable for a scientist, but to me it had all the coherence of a Labrador Retriever, chasing down fascinating rabbit trails and never quite getting back to the original point. Two stars for a bait and switch.

Yes, CarolBeth, tell us how you REALLY Feel about this one.

[Dick Crockett · Rating 4 out of 5]

Although retired many years since, I came to this book as a former practicing field geologist. However, what I gained from it was less about geological matters but more about the concomitant science that the author deploys to sustain his reasoning. For example, I much appreciated his summary of where we stand (in about 2024) as to the now-numerous discoveries of Hominid fossils over much of Africa. From reading the contributions of other reviewers, I gather that there are criticisms to be made about the author’s presentation of the way that DNA evidence offers clues as to population history. Nevetheless, as a layman in this field, I found this a useful primer.

I worked in southern Africa and during that time I encountered the San people (aka “Bushmen”), one of the very last hunter-gatherer communities on the planet. Literally looking down on the these folk whose average adult height was a good 50 cm less than mine was a vivid reminder of the genetic diversity within African humanity as compared with populations elsewhere. This does, however, beg the question whether the few thousand individuals who are postulated to have survived the after effects of the Toba eruption refers only to populations that had found their way to Eurasia. If this had been been a cull that affected the whole of humanity, surely the contemporary African population should be less genetically diverse than is the case?

I seem to remember that there are some interesting archaeological clues to be found in India and elsewhere above and below volcanic deposits attributed to Toba; it would have added interest to the story to have some consideration of these to be added to the story.

[Bill Holmes · Rating 4 out of 5]

I enjoyed reading Prothero’s “When Humans Nearly Vanished,” but I’ve given it only four stars because I feel the book is not all that it could be. The premise is that a super volcano erupted in Indonesia roughly 74,000 years ago, an event confirmed by ice cores, ash deposits and studies of the caldera itself. The eruption was enormous, dwarfing historically recent eruptions like Krakatoa (1883), Pinatubo (1991) and Tambora (1815). The resulting volcanic winter and acid rains decimated life on the planet, an outcome that is reflected in a “genetic bottleneck” that appears in the genome of pandas, tigers, great apes and humans, among others. The hypothesis is that we humans, as a species, almost went extinct because of that eruption.

The topic is a good excuse for digressions into geology, paleontology, volcanism, the five Great Extinctions, genetics and the prospects for future super volcanic eruptions that might upend human civilization, or worse. It’s all very interesting, but these topical surveys are necessarily high level and they cover familiar ground for those who have explored these subjects before.

So, in sum: an enjoyable diversion and worth reading, but it could have been made more exciting and more complete. I was hoping for something more along the lines of “T-Rex and the Crater of Doom,” but this isn’t quite in that league.