Event That Left Only 1,000 Humans Alive

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Around 800,000 to 900,000 years ago, a genetic bottleneck occurred, drastically reducing the human population. This event led to the extinction of 98.7% of the population, leaving only about 1,280 individuals. The main cause was a significant climate shift called the middle Pleistocene transition, which brought longer and harsher glacial cycles. This change made it difficult for early humans to hunt, forcing them to adapt while some animals went extinct. Scientists are still studying the exact cause and timing of this bottleneck.   Animation is created by Bright Side. ---------------------------------------------------------------------------------------- Music from TheSoul Sound: https://thesoul-sound.com/   Check our Bright Side podcast on Spotify and leave a positive review! https://open.spotify.com/show/0hUkPxD34jRLrMrJux4VxV   Subscribe to Bright Side: https://goo.gl/rQTJZz ---------------------------------------------------------------------------------------- Our Social Media: Facebook: https://www.facebook.com/brightside Instagram: https://www.instagram.com/brightside.official TikTok: https://www.tiktok.com/@brightside.official?lang=en   Stock materials (photos, footages and other): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ----------------------------------------------------------------------------------------  For more videos and articles visit: http://www.brightside.me  ---------------------------------------------------------------------------------------- This video is made for entertainment purposes. We do not make any warranties about the completeness, safety and reliability. Any action you take upon the information in this video is strictly at your own risk, and we will not be liable for any damages or losses. It is the viewer's responsibility to use judgement, care and precaution if you plan to replicate.

Transcript

00:00Can you imagine that all modern humans came from about a thousand people?

00:05Around 800,000 to 900,000 years ago, almost all of our ancestors disappeared, leaving

00:11about 1% of the population behind.

00:14So what the heck happened?

00:17The Earth often goes through glacial cycles, things that we call ice ages.

00:21Back in the past, they were pretty mild and happened regularly, about every 41,000 years.

00:27The ice ages happened because of the Earth's axis.

00:30Our planet is slightly tilted at an angle, which is why its axis isn't straight up.

00:35Over thousands of years, this tilt has changed a bit.

00:38This teeny-tiny shift completely changes how much sunlight we receive, especially at the

00:43poles, and leads to incredibly strong cold or warm periods.

00:48About 2.6 million years ago, when early humans were settling in on Earth, the Pleistocene

00:54epoch started.

00:55That's the era we traditionally call the Ice Age, the one from the movies.

00:59Large ice sheets completely covered parts of North America, Europe, and Asia.

01:04It wasn't constant ice everywhere all the time.

01:07These glacial cycles came and went, and sometimes ice sheets melted for a while.

01:11But overall, things were still much snowier and colder compared to now.

01:16We can still see the evidence of this from back in the day.

01:19Those glaciers carved out valleys and left behind some awesome things like moraines and

01:24fjords.

01:25And since sea levels were super low, a huge part of the world was land.

01:29This allowed people and animals to travel between continents and spread everywhere.

01:34It was the time of the megafauna.

01:36You all know about it from the movies.

01:38Wooly mammoths, saber-toothed cats, giant ground sloths, and mastodons.

01:43Our ancestors had some fun times hunting all those giants.

01:47Humans didn't come from one lineage.

01:49It wasn't like monkeys slowly turned into humans.

01:52We also consisted of many species – Homo erectus, Neanderthals, and so on.

01:57But only one species, Homo sapiens, survived and turned into modern humans.

02:02Harsh conditions forced them to get smarter.

02:05They learned how to make tools, clothing, and shelters to survive.

02:08They became hunter-gatherers and invented fire, which turned out to be super useful

02:13during the Ice Age, you think?

02:15But they had no idea what horrible change was coming.

02:19Something disastrous happened about 800,000 to 900,000 years ago.

02:24Humans faced a drastic population crash.

02:27Only 1,280 people survived, give or take.

02:31Some 99% of early humans were wiped out, and this tiny 1% was lucky enough to become our

02:37ancestors.

02:39This almost-extinction, unsurprisingly, was the climate's fault.

02:43It was the Middle Pleistocene transition.

02:46The Earth's orbit around the Sun changed its shape a bit.

02:49Ocean levels dropped.

02:50A lot of stuff was happening, and the Earth's climate was going wild, becoming incredibly

02:55cold and dry.

02:56The seas suddenly got chillier, and Africa and Eurasia experienced horrible droughts.

03:02Looking for food was almost impossible.

03:06Scientists learned this by taking the DNA of about 300,000 people from all around the

03:11world.

03:12They used a new method to help them map the history of human evolution over a million

03:16years and learn more about it.

03:18No wonder we can barely find any fossils from that time.

03:21There was almost no one around.

03:23What's interesting is that before that happened, most apes had 24 pairs of chromosomes.

03:29But because the population became so small, two sets got fused together, and we ended

03:34up with 23 pairs.

03:36This was the final straw that separated us from other apes.

03:40Chimpanzees, gorillas, and orangutans all have 24 pairs, but our fused one became known

03:46as the human chromosome.

03:48Like a ripple effect, this little thing influenced our brain side, helped us start walking on

03:52our two's, and even formed language.

03:55It took humans about 100,000 years to recover from this catastrophe.

04:00Only after all that time, they started spreading around again.

04:04Isn't that insane how we managed to go from 1,000 to 8 billion people?

04:09In any case, the Ice Age finally ended about 11,700 years ago.

04:14The warm period, called the Holocene, began.

04:17As things got warmer, human civilizations finally began to develop.

04:215,000 years ago, it was Ancient Egypt, then the Indus Valley Civilization, Ancient China,

04:27and others.

04:28And while we'd been thriving for a while, there's one catch.

04:31The Middle Pleistocene Transition changed the length and intensity of glacial cycles.

04:37Before the transition, sure, there was the Ice Age, but the cold was milder, and the

04:41glacial cycles were shorter.

04:44Ice got covered in ice sheets about every 41,000 years.

04:48But after the transition, the glacial periods became longer and more severe.

04:53These cycles started following a new pattern.

04:55Although they happened every 100,000 years, they were super intense.

04:59Ice sheets grew large, even extending to the south.

05:03So from now on, ice ages, that will continue to happen in the future, will be a bit different.

05:09The next one should be at least 50,000 years from now, maybe longer.

05:13That's good for us because it'll occur later.

05:16But at the same time, the consequences will be stronger.

05:19What our ancestors went through is called a population bottleneck.

05:23That's what we call a sudden and huge reduction in the size of a population.

05:28Usually it happens because of things like earthquakes, floods or droughts, fires, and

05:32even human actions.

05:34Just a few people survive, and only they can pass their genes to future generations.

05:39And we've got plenty of such bottlenecks in history.

05:42Our modern species, Homo sapiens, originally lived in Africa.

05:46Around 60,000 to 80,000 years ago, a small group of them left Africa and spread across

05:51the world.

05:52It wasn't on a whim, though.

05:54They had to move somewhere because of the droughts and huge climate problems in Africa

05:58at that time.

05:59They had to go look for food and find new places to live.

06:03They traveled through the Middle East, moving into Europe and Asia, and eventually reaching

06:08Australasia and the Americas.

06:11They quickly settled across different continents and started mixing with local human-like species

06:15like Denisovans and Neanderthals.

06:18But there was a problem.

06:19Originally, the African species were super genetically diverse.

06:24But since only a small part of them decided to move out, they carried just a bunch of

06:28these diverse genes with them.

06:30Unfortunately, this caused a bottleneck for everyone.

06:33Human-like species from other parts of the world became less genetically diverse.

06:38Since they had a smaller gene pool, they became more vulnerable to all the harmful

06:42stuff.

06:43The African population also had a drop in genetic diversity.

06:47But at least humans managed to survive.

06:49Although eventually, non-African populations really dropped, and there were no Neanderthals

06:55or Denisovans left.

06:56Only us, Homo sapiens.

06:58That's why we can say that all modern humans came from Africa.

07:03Early humans sure had it rough.

07:05About 74,000 years ago, they went through yet another disaster, the Toba Catastrophe.

07:11But keep in mind that all these things are just a hypothesis.

07:14It's not certain whether it actually happened.

07:17Now basically, scientists think that there might've been a super volcanic eruption at

07:21Lake Toba in Sumatra, Indonesia.

07:23This volcano, going crazy, was an absolute catastrophe for Earth's climate and humans.

07:29The eruption was one of the most powerful volcanic events in the last 2 million years.

07:34It spewed out from 670 to 1,000.5 cubic miles of lava and volcanic stuff.

07:41Just so you know, there are about 3,100 cubic miles of water in our planet's entire atmosphere,

07:47and this eruption had almost half as much lava.

07:50This horrendous disaster led to the formation of Lake Toba, a massive caldera lake in Sumatra.

07:56It also spewed out tons of ash and sulfur dioxide into the atmosphere.

08:00This caused the so-called volcanic winter, which means that while it's not actually winter,

08:05the temperatures drop and the planet is freezing because all these ash clouds are blocking

08:10the sunlight from reaching Europe.

08:12This event affected climate patterns for years to decades.

08:16This also most likely sped up the arrival of the next glacial cycle.

08:20Luckily, humans are crazy good at surviving.

08:23The global human population was reduced to a few thousand people yet again, and they

08:28still managed to overcome this.

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