ExtinctZoo - This Killed All But 1,000 Humans 900,000 Years Ago

Episode Date: July 8, 2024

Our ancestors had it ROUGH. On the bright side, there was a good chance you would've been the world's best at something...

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At the time, no one really had a good idea of what this something could have been. But during the 1990s, scientists started to connect it to a massive volcano that erupted 74,000 years ago, Lake Toba. The idea was that this eruption, which took place in Indonesia, was so violent that it had a catastrophic effect on humans, with estimates finding it to have had an explosive power 10,000 times more powerful than the eruption of Mount St. Helens, leading to the evisceration of local areas and causing severe change in climate that ultimately pushed humans to the brink of extinction, with roughly only 3,000 to 10,000 individuals surviving.

For a long time, this hypothesis stood strong, and was the leading belief in what caused our drop in genetic diversity. Although in recent times, there has been a growing consensus that the Lake Toba eruption did not have a profound impact on humanity, with one major argument being that while some populations were no doubt affected, other groups that actually lived quite close to the volcano itself seemed to persist, drawing questions on just how deadly this eruption was. Additionally, newer models show that its climatic impacts were probably not as drastic as

originally thought. And not to mention, the timing did not align well with a drop in population. This all about upended the bottleneck notion, and some don't even think it happened at all, citing that DNA research during the 1970s was far from perfect and considered ancient by today's standards. And with a quote-unquote death of the Lake Toba catastrophe idea, popularity and talk around human bottlenecks basically seized. Until that is, late 2023, when a much more advanced study carried out by anthropologists

found a severe evolutionary bottleneck that seemed to have played out between 800,000 and 900,000 years ago, during the clabrian stage of the Pleistocene. Naturally, because this was over 300,000 years ago, the affected population was not made up of modern humans, as we had yet to evolve. Rather, it involved an ancestral line of earlier humans. The discovery was made by analyzing over 3,000 modern humans' genomes,

allowing scientists to take a glimpse into the past, so to speak, which revealed that this major die-off left a surviving population as low as 1,280 people, meaning that humanity saw the extinction of 98.7% of the entire population. To put into perspective how insane that is, it's like a meteor striking the earth today and killing roughly 7.9 billion people. At such low numbers, our ancestors would have been considered endangered by all means, making them a rare sight at the time, a stark contrasts compared to the present where humans are easier to find than miss. And unfortunately for survivors,

it wasn't a quick turnaround following their decline. With researchers estimating, that this critically low population persisted for over 117,000 years, during which early humans were holding on by only a thread, and fighting for every inch of their survival. The scientists also used known false remains to back this proposed bottleneck, citing the lack of hominem bones that date between 950,000 and 650,000 years in age, with only a few specimens hailing from this time. And funnily enough, what remains are known of simply create more questions than they answer,

because their taxonomic status are not clear, meaning scientists don't really know what Homo species got the short end of the stick. Some research suggests that we can rule out Homo antecessor due to skull comparisons, and that the mysterious species in question were more similar to Homo Hidalbergensis, the archaic human species considered to be the last common ancestor between Neanderthals and modern humans. And in another twist, the research has proposed that the survivors of this event may have been the ones who actually evolved into Heidelbergensis.

And this does make some sense, as we know that such evolution like this can sometimes occur in other mammals during bottlenecks, as the loss of genetic variation causes the new population to become genetically distinct from the original population. Extinction events in general can often play a huge role in evolution, pushing survivors to adapt or die. So what exactly caused this obscure moment in human history that may have single-handedly been responsible for the eventual creation of Homo sapiens?

Well, like many times in Earth's history, it appears that a dramatic shift in climate change was the culprit. Specifically, the likelyest suspect is the middle Pleistocene transition event, which not only had profound impacts on our ancestors, but the entire planet, too. This event was basically a major change in the glacial cycle that dominated Earth. Beforehand, these cycles lasted for about 41,000 years and were characterized by thin ice sheets. Whereas after the transition, Earth started to see thicker ice sheets and experienced longer cycles that lasted up to 100,000 years, causing immense strain on environments. It typically thought that a gradual decrease in carbon dioxide and a reduction in regoliths

triggered this shift between 1.25 and 0.7 million years ago. Despite typically being regarded as one large event, it was characterized by numerous acute events scattered throughout, one of which is known as the 0.9 MA event. For now, this exact moment within the transition is signed his best bet on what specifically took out many of the early human populations, as it was the coldest point during the entire transition and saw drier conditions formed throughout Africa and Eurasia. This would have changed the landscape drastically and affected many animals that lived alongside our ancestors, making hunting a challenging task. And dental evidence actually supports this, as many prehistoric ungulates from that time

have distinct isotope levels, showcasing how they were forced to switch their diet in a short period of time, meaning that it wasn't only early humans that struggled. They just got it worse than most. One reason behind this may have been their lack of control over fire, according to the researchers. For now, barely any fire sites are known from the 0.9 MA event, a sign that perhaps our ancestors weren't as technologically ahead as they needed to be to endure the cold. This lack of fire is also the main belief on why early humans suffered for so long, with the survivors only being capable of recovery after fire became more widespread. And once fire was mastered, early humans apparently rose in the ashes at lightning speed.

estimated that by 813,000 years ago, the number of archaic humans had jumped by over 2,000 percent. Quite the comeback story. It's also possible that a lack in other technologies, like clothing, may have played a role in both the original die-off and bounce-back as well. Surprisingly, despite the amount of damage ancient humans endured, some animals were more unfortunate, going fully extinct, including different kinds of pumas, meganterion, and xenosion. Meanwhile, in the waters, they were more unfortunate. Things weren't great either, with a separate study, finding that this event eradicated over 100 different marine species, a testament on how lucky we had it, relatively speaking.

Naturally, there's a lot of contention around this idea. With some people denying the hypothesis as a whole, while others disagreeing that climate was to blame or that the proposed timings mentioned are incorrect. Certain individuals even think there was no extinction event, period, with their hypothesis being that something more random like a genetic mutation took place, which technically could have given one population a big edge over the others. Even the scientists who wrote the paper have said that follow-up research needs to take place in order to confirm the accuracy of their bottleneck suggestion. Fortunately since 2023, more research has indeed taken place,

and the results both solve a few questions and create a few more. As an independent team found that while the bottleneck likely did happen, it may have taken place earlier than first thought, playing out over a million years ago. If true, it would prove that the 0.9 MA event was not the main culprit behind our ancestors near extinction. But of course, another study has also come out that actually backs the original paper and its timings, although disagree that the cold was solely to blame. This third study proposed that while climate was the trigger, the real secret behind the bottleneck was mass migrations out of Africa. The idea is that as the temperature plummeted and Africa became more arid, Savannah started to expand across the majority of the continent, pushing early humans out of their

homeland. Ironically, in a case of a double-edged sword, they were able to successfully migrate thanks to land routes that emerged as the ice sheets grew and water levels rose. But on the other hand, nearly no one survived the journey, due to nearly universal brutal conditions, which included a severe lack of fresh water. No doubt, all this talk the original study created has spurred a lot of new research. So hopefully in the near future, we can clear up all these disagreements, and finally solve the mystery behind our ancestors close brunt. off your home, travel for life, drive a Ferrari. In celebration of the world premiere of the Monopoly, Big Board Buckslot Machine by Aristocrat Gaming, Yamava Resort and Casino at San Manuel

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