- Five catastrophes nearly wiped out humanity over 74,000 years
- The Toba bottleneck theory is now widely disputed by archaeologists
- Agriculture brought stability but worsened nutrition and disease
Around 74,000 years ago, the Toba supervolcano in Sumatra erupted with enough force to launch 670 cubic miles of ash into the sky.
For years, geneticists believed the eruption caused a human population bottleneck, reducing our entire species to fewer than 3,000 individuals.
The YouTube channel Barely Evolved revisits this and four other near-extinction events in a countdown that balances dark humor with a genuinely unsettling question: how many times did our species nearly vanish?
The answer, according to the video's ranking, is at least five. Each event stripped away something essential, whether food, shelter, health, or sheer numbers.
Ice and Bone Needles
The Last Glacial Maximum, roughly 20,000 years ago, buried much of North America, Europe, and Asia under ice sheets two miles thick. Global temperatures dropped about 6 degrees Celsius.
The human population across the Old World may have fallen to somewhere between two and three million, clustered in glacial refugia where conditions remained just barely tolerable.
Survival demanded constant adaptation. Early humans stitched animal hides with bone needles, hunted megafauna armed with sharpened sticks, and sheltered in mammoth-bone huts. A simple infected cut could kill. There were no antibiotics, no emergency care, only chewed plants and hope.
Yet this period also produced the cave paintings at Lascaux. Pressed to the edge, humans whose origins stretch back 300,000 years made art.
The Price of Staying Put
Around 10,000 years ago, agriculture seemed like a good idea. Instead of chasing mammoths across hundreds of miles, early farmers planted wheat, barley, and lentils. They settled in permanent villages.
The trade-offs arrived quickly. Dense living conditions accelerated disease transmission. Diets narrowed, trading the protein diversity of hunting for grain-heavy meals that brought vitamin deficiencies and dental decay.
Archaeologists have found ancient skeletons showing signs of malnutrition, anemia, and severe tooth erosion.
The agriculture paradox
Farming provided caloric stability but reduced nutritional diversity. Skeletal evidence from early agricultural communities shows shorter stature, more disease markers, and worse dental health compared to hunter-gatherer populations from the same regions.
One bad drought, one locust swarm, one flood, and an entire village starved. The shift to farming traded daily uncertainty for seasonal catastrophe.
Empires Built on Annihilation
Traditional estimates place deaths from the Mongol invasions of the 13th century at around 40 million, roughly 10% of the world's population, though some historians now argue the true figure may be significantly lower. Genghis Khan's armies carved out the largest contiguous land empire in history, stretching from China to Eastern Europe.
Their efficiency was systematic. Horse archers could strike from 300 yards at full gallop. Cities that resisted were razed entirely. Survivors were sometimes pressed into service as human shields for the next siege.
Key figure
Up to 40 million
Traditional estimate of deaths during the Mongol invasions, though revisionist scholars propose lower figures
The scale of killing was so vast that some climate researchers have suggested the resulting reforestation, as farmland reverted to forest, may have briefly cooled the planet.
When Fleas Carried Empires to Their Knees
In 1347, Yersinia pestis arrived in Europe aboard rats and fleas from Central Asia. The Black Death killed between 30% and 60% of Europe's population within a few years. Entire villages were abandoned. Economies collapsed.
The bacterium spread through flea bites, respiratory droplets, and contaminated surfaces. Symptoms included swollen lymph nodes, fever, and vomiting blood. Death typically followed within days.
You exist because a thousand people before you didn't die when they should have.
Barely Evolved
Doctors wore beaked masks filled with flowers, believing bad air caused the plague. The actual mechanism, flea-borne bacterial transmission, would not be understood for another five centuries.
The Human Population Bottleneck That May Not Have Been
The Toba volcanic eruption sits at the top of the video's ranking, and the story it tells is dramatic: a volcanic winter lasting six to ten years, global temperatures crashing by as much as 15 degrees Celsius, humanity reduced to a few thousand survivors. Every person alive today, the theory goes, descends from that tiny remnant.
The reality is more complicated. Paleoanthropologist John Hawks at the University of Wisconsin-Madison has argued that the so-called Toba bottleneck simply did not happen.
Archaeological evidence from India's Jurreru Valley shows stone tools both above and below thick layers of Toba ash, with no obvious interruption. Studies in East Africa found no evidence of volcanic winter conditions after the eruption.
Genetic analyses have not detected a bottleneck coinciding with the Toba eruption. The population contraction visible in human DNA may instead reflect the out-of-Africa migration around 50,000 years ago, not a volcanic catastrophe 24,000 years earlier.
The eruption was real, and its effects were global. But the neat story of near-extinction followed by miraculous survival appears to be overstated. The evidence now suggests that human populations endured, adapted, and in some cases barely noticed.
Survival as the Rule, Not the Exception
Barely Evolved frames human existence as improbable, and across 74,000 years of ice ages, plagues, and invasions, the framing holds a certain appeal.
More History
Viking DNA: What Ancient Genetics Reveals About Modern Scandinavians
Modern Scandinavians carry Viking ancestry, but genetic research reveals the story is more complex than national myths suggest. The Black Death and subsequent immigration reshaped…
→But the deeper pattern may be the opposite. Humans survived Toba not because a lucky few clung to existence, but because populations were more widespread and more resilient than the bottleneck theory assumed.
The archaeological and genetic record keeps revising this story in one direction: toward greater human tenacity than we previously credited.
The question is not whether our ancestors survived against impossible odds.
It is whether the odds were ever quite as impossible as we thought.
Sources
- Primary Source: The Worst Time in History to Be Born as a Human (Barely Evolved, YouTube)
- Additional Context:
- The so-called Toba bottleneck simply didn't happen (John Hawks)
- Toba catastrophe theory (Wikipedia)
- Destruction under the Mongol Empire (Wikipedia)
