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The Shocking Near-Extinction of 1,280 Humans That Shaped Our Survival

Humans walking in the windy dessert.
Humans walking in the windy dessert. Image by Ricky Esquivel via Pexels

A groundbreaking new study has revealed that apparently 930,000 years ago, our ancestors were down to an astonishingly small 1,280 breeding individuals. This population bottleneck lasted for a staggering 117,000 years putting our very survival in jeopardy. Researchers think that this event could explain the mysterious gap in the fossil record during the African-Eurasian period. To think humanity almost shared the fate of the dinosaurs! 

Frozen Assets Lead To Stock Crash

ice caps
Ice caps melting along the Arctic coast. Image by Denis Burdin via Depositphotos

Sid the sloth isn’t the only one who struggled during the Ice Age. The researchers believe that a series of ice ages, known as glaciation events, were to blame for humanity’s catastrophic population decline. The changing global climate caused droughts that wiped out essential food sources and made life extremely tough.  According to the study, the human population was reduced by a whopping 98.7 percent! This bottleneck lasted until about 813,000 years ago when the population rebounded somehow.

A New Tool To Pry Open The Past

Diagram of the contents of the human genome.
Diagram of the contents of the human genome. Image by NHS National Genetics and Genomics Education Centre, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons

The researchers behind this study have developed a new tool to peer into our ancient history. They call it the fast infinitesimal time coalescent process. This technique allows them to estimate the size of ancient human populations by analyzing our modern human genomic sequences. Using this method, researchers could discover the sharp decline in the number of breeding individuals around 930,000 years ago. 

Gap in the Fossil Record

People walking in dessert
People walking in dessert. Image by cottonbro studio via Pexels

You see during this bottleneck period, fossil evidence is sparse, suggesting that there were only a few humans around to leave behind remains. One anthropologist at Sapienza University in Rome, Giorgio Manzi, argues that this population crash might explain gaps in the fossil record.  While this idea sounds plausible, some researchers aren’t convinced. Some say this explanation may be too simplistic.

So Why The Skepticism 

Couple in the grass.
Couple in the grass. Image by cinto 13 via Pexels

Nicholas Ashton, a leading paleolithic archaeologist at the British Museum, has raised eyebrows, questioning whether the fossil evidence really aligns with the proposed global crash theory. He argues that many questions remain unanswered. For example: what caused the population to miraculously recover after 120,000 years? My guess is a guy in the group volunteered to eat something he shouldn’t, it turned out to be fine and we had a new food source.

A Genetic Gamble

Where Did the First Human Populations Settle After Africa
Image by Charles Robert Knight – https://digitalcollections.amnh.org/CS.aspx?VP3=SearchResult&VBID=2URMLB8Q7PBO&PN=1&WS=PackagePres, Public Domain, https://commons.wikimedia.org/w/index.php?curid=136771404 via Wikimedia Commons

The study also revealed that we lost a huge chunk of their genetic diversity during the bottleneck. Researchers estimate around 65% were lost among Pleistocene ancestors. With those odds we could’ve had tails or maybe some extra eye colors! The evolution of modern humans may have been negatively impacted for some time. Despite this, the small surviving population eventually regained enough diversity to evolve into the humans we are today. Even in the darkest of times, humans always have a chance for a comeback. 

How It Shaped Human Evolution

Neanderthals and the woolly mammoth.
Neanderthals and the woolly mammoth. Screenshot from The Life and Death of a Neanderthal (Shanidar 1) Source: YouTube Channel: Stefan Milo

The researchers also suggest that this population crash may have helped differentiate between Neanderthals, Denisovans, and modern humans. Just as pruning a plant can force it to grow stronger and develop new branches, population reduction likely forced our ancestors to adapt and evolve in unique ways. This could have led to the distinct genetic and physical traits seen in these three groups.

Supercharged Evolution

Stages of human development towards shading tails.
Stages of human development towards shading tails. Screenshot from Did You Know: Why Don’t Humans Have Tails? Source: YouTube Channel: Encyclopaedia Britannica

With only 1,280 breeding individuals left, natural selection could have worked faster. So it’s more likely traits that improved survival in harsh conditions were passed on. This accelerated evolution might explain the development of complex brain functions and adaptability seen in modern humans. Our big brain might have been a coping mechanism!

The Numbers Aren’t Crunching 

Genetic diversity within and between populations
Changes in the number and order of genes (A-D) create genetic diversity within and between populations. Image by Jthiele at English Wikipedia, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Another who’s not so convinced that the study’s findings are as precise as they claim is Stephan Schiffels, a population genetics expert. Despite how novel the method is, he is still particularly skeptical about the ability to pinpoint such exact population figures from nearly a million years ago. Other geneticists have similar worries.

Limited Data Sparks Debate Among Experts

Principal component analysis of 1,059 present-day west Eurasian and North African individuals, with ancient individuals
Principal component analysis of 1,059 present-day west Eurasian and North African individuals, with ancient individuals. Image by Olalde, Iñigo et al. (2019), Public domain, via Wikimedia Commons

Janet Kelso, a computational biologist, argues that the genetic signals indicating a bottleneck are most noticeable in present-day African populations. So the bottleneck may only have affected certain groups rather than affecting the global population. She says the study should be interpreted with caution. Aylwyn Scalley, a human evolutionary genetics researcher at Cambridge University, also found the conclusions to be unconvincing. Pontus Skoglund of the Francis Crick Institute thinks without extra supporting evidence, it’s hard to say for sure whether this bottleneck truly happened as described. 

And How Did We Survive

the ancestral population substructure (genetic lineages) of modern humans about 30-15kya.
The ancestral population substructure (genetic lineages) of modern humans about 30-15kya. Image by Jayasinghe23, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

While the study provides new insights into ancient human history, it also raises more questions than it answers. Did natural selection play a role in their survival and eventual recovery? And what does this bottleneck mean for our understanding of early human societies? Were the last group of humans ginger? There’s just so much left to uncover.

In short

Man holding flare in a cave.
Man holding flare in a cave. Image via Unsplash

The idea that humanity was once on the brink of extinction is both fascinating and sobering. I mean now humans run the world so it’s hard to imagine us at the bottom of the food chain! However, despite these intriguing insights, more research is needed to confirm the bottleneck theory. Who knows what quirky traits we used to have?

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