Human Evolution: Crash Course Big History #6

Summary

This Crash Course Big History episode humorously explores human evolution, from primate ancestors to Homo sapiens. It discusses the rise of bipedalism, tool use, and collective learning, leading to significant technological advancements. It also ponders the Hobbes vs. Rousseau debate on human nature, suggesting that our evolutionary past may have shaped our current societal structures and behaviors.

Takeaways

• 🌏 The Planet of the Apes films are a humorous introduction to the evolutionary process that led to humans, who are considered 'apes' in this context.
• 🎥 The script humorously references the various iterations of the Planet of the Apes franchise, including sequels, prequels, and reboots.
• 🧬 Humans are one of the most complex entities in the universe, with biological and cultural complexity that sets us apart.
• 🌳 Around 65 million years ago, the extinction of dinosaurs allowed for the adaptive radiation of small mammal ancestors, leading to the diversification of primates.
• 🌊 Plate tectonics shaped the continents, affecting primate evolution and leading to the development of new world monkeys and marsupials in Australia.
• 🏞️ Environmental changes in East Africa, such as the transition from forests to savannas, influenced the development of bipedalism in human ancestors.
• 🧠 Bipedalism in human ancestors freed up hands for tool use, a significant step in our evolutionary history.
• 🛠️ Homo habilis marked the beginning of tool use, with evidence of stone flaking for cutting, although technological advancement was minimal.
• 🔥 Homo ergaster and Neanderthals developed more complex tools and the controlled use of fire, which was crucial for survival and further brain development.
• 🤝 Collective learning, or the accumulation of knowledge and technological improvement over generations, is a key factor in human advancement.
• 🎨 Around 40,000 years ago, Homo sapiens developed art, music, and other cultural expressions as a result of collective learning.
• 🌾 The advent of agriculture and the establishment of property rights marked significant shifts in human society, with debates on whether these changes were beneficial or detrimental.
• 🌍 The Mt. Toba eruption nearly wiped out the human population, but a small group survived and repopulated the world, demonstrating human resilience and adaptability.

Q & A

What is the significance of the Planet of the Apes films in the context of the video script?

The Planet of the Apes films are used metaphorically to introduce the concept of primates evolving and shaping the Earth, with a humorous nod to the fact that humans are the apes that have transformed the planet, not the apes from the movies.

Why does the video script discuss humanity's significance in Big History despite humans' relatively recent appearance?

The script discusses humanity's significance because humans are naturally curious about their place in the universe's timeline, and because humans represent a unique and complex change in the cosmos.

What evolutionary milestone is attributed to the australopithecines mentioned in the script?

Australopithecines are credited with the development of bipedalism, which is a significant evolutionary milestone as it freed up their hands for other tasks and marked a shift from the bow-legged stance of their ancestors.

How does the script describe the technological advancements of early human species like homo habilis and homo ergaster?

The script describes early human species like homo habilis and homo ergaster as having basic tool-making abilities, but with little technological improvement over time, suggesting a slow pace of collective learning and innovation.

What is the concept of 'collective learning' as discussed in the script?

Collective learning refers to the ability of a species to retain and build upon information across generations, allowing for faster technological and cultural progress without waiting for genetic evolution to occur.

Why does the script mention the invention of the internet, animated GIFs, Dr. Who, and Tumblr as examples of human achievements?

These inventions and cultural phenomena are mentioned to highlight the creativity and innovation of humans, emphasizing the unique and complex nature of human civilization.

What major event around 74,000 years ago is mentioned in the script, and what was its impact on human population?

The script mentions the super-eruption at Mt. Toba, which reduced the human population to a few thousand individuals, leading to a genetic bottleneck that affected human genetic diversity.

How does the script compare the lifestyle of early foragers to that of later agricultural societies?

The script suggests that early foragers had a relatively short workday, less wealth disparity, and potentially greater equality, while acknowledging that life could also be harsh with high murder rates and abandonment of the old or disabled.

What debate does the script refer to when discussing the impact of societal structures on human nature?

The script refers to the Hobbes vs. Rousseau debate, which questions whether humanity is fundamentally good but corrupted by society or if humans are inherently flawed and require societal structures for order.

What does the script suggest about the future of human collective learning and innovation?

The script implies that with a large global population and rapid communication, human collective learning and innovation are likely to continue at a rapid pace, leading to further advancements in technology and culture.

Outlines

00:00

🦍 Evolution and Human-Centric Big History

John Green introduces the topic of the Planet of the Apes films and humorously notes that they are not documentaries, but rather a metaphor for human evolution. He discusses the evolutionary journey of primates from East Africa and how they shaped Earth. Green emphasizes the importance of humanity in Big History, not just because we are humans, but also due to our unique complexity in the universe. He mentions the invention of the internet, animated GIFs, Dr. Who, and Tumblr as examples of human achievements. The paragraph sets the stage for discussing human evolution, starting with the extinction of dinosaurs 65 million years ago and the rise of a shrew-like ancestor of humans.

05:02

🌏 Geological and Biological Evolution

This paragraph delves into the geological events that shaped the Earth, such as the separation of continents and the formation of the Himalayas. It discusses the adaptive radiation of marsupials in Australia and the divergence of the ape lineage from old-world monkeys around 25 to 30 million years ago. The script clarifies that humans did not evolve from chimpanzees but share a common ancestor that split around seven million years ago, leading to the emergence of bonobos and humans. The paragraph also highlights primate characteristics such as large brains relative to body mass, forward-facing eyes for depth perception, and grasping hands, which are remnants of their arboreal past.

10:04

🤝 Primate Behaviors and Social Hierarchies

The script explores the shared behaviors and social structures between humans and our closest relatives, the chimpanzees. It notes the propensity for both species to form alliances and challenge alpha males, as well as engage in aggressive behaviors against outsiders. The paragraph contrasts this with the more peaceful bonobos, which are female-led and use sexual interactions to reduce inter-group tension. The discussion then shifts to the environmental changes in East Africa that led to the development of bipedalism in our ancestors, freeing up their hands for tool use and other activities. The paragraph also touches on the limited technological advancements of early hominids like Australopithecines and Homo habilis.

15:05

🛠️ Technological Evolution and Collective Learning

This paragraph focuses on the technological evolution of early humans, starting with Homo ergaster and their creation of teardrop hand axes, which signifies the first signs of technological improvement through social learning. The script explains the concept of collective learning, which is the ability of a species to retain and build upon knowledge across generations, leading to rapid advancements in technology and culture. It highlights the achievements of Homo antecessor, Homo Heidelbergensis, Neanderthals, and eventually Homo sapiens, including the controlled use of fire, blade tools, wooden spears, and composite tools. The paragraph concludes by emphasizing the importance of collective learning in human progress and survival.

🎨 The Richness of Early Human Life and Collective Learning

The script describes the lifestyle of early humans, who engaged in foraging and had a relatively short workday compared to later agricultural societies and modern office workers. It discusses the health benefits of their nomadic lifestyle and the potential for greater social equality due to the contributions of female gatherers. The paragraph also addresses the debate between Thomas Hobbes and Jean-Jacques Rousseau on the nature of early human life, with Hobbes viewing it as 'nasty, brutish, and short,' while Rousseau argues that the advent of agriculture and private property led to societal corruption. The script concludes by reflecting on the impact of collective learning on human survival and the potential consequences of the Mt. Toba eruption 74,000 years ago, which nearly wiped out the human population.

🌟 The Recovery and Expansion of Humanity

The final paragraph discusses the recovery of the human population after the Mt. Toba eruption, which reduced it to a few thousand individuals. Despite this genetic bottleneck, humans managed to spread out of Africa 64,000 years ago and adapt to diverse environments while continuing to innovate. The script suggests that the process of collective learning was about to lead to a significant acceleration in human development, setting the stage for the rapid advancements in complexity and civilization that would follow in the millennia to come.

Keywords

💡Evolutionary process

The evolutionary process refers to the gradual development of different species from a common ancestor over time. In the video, it is mentioned in the context of primates evolving and spreading out of East Africa, which is integral to understanding humanity's place in the larger story of life on Earth.

💡Adaptive radiation

Adaptive radiation is a process in evolution where one ancestral species rapidly diversifies into several new species as a result of different environmental pressures. The script discusses how this phenomenon led to the emergence of new world monkeys and marsupials in Australia, illustrating the diversity of life on Earth.

💡Plate tectonics

Plate tectonics is the theory that describes the movement of Earth's lithosphere, which is divided into tectonic plates. The script mentions how plate tectonics contributed to the separation of continents like the Americas from Eurasia and the formation of the Atlantic Ocean, affecting the distribution and evolution of species.

💡Homo habilis

Homo habilis is an early human species known for its association with the use of stone tools. The script highlights this species as an example of early technological advancement in human evolution, showing the beginnings of tool-making and the potential for cultural transmission of skills.

💡Collective learning

Collective learning is the ability of a species to accumulate and build upon knowledge across generations. The video emphasizes its importance in human development, as it has allowed for the progression from simple stone tools to complex technologies, underpinning the advancement of human civilization.

💡Bipedalism

Bipedalism is the ability to walk upright on two legs. The script explains that bipedalism in human ancestors was a significant adaptation to the changing environment of East Africa, allowing for more efficient movement across the savanna and freeing up hands for tool use.

💡Homo erectus

Homo erectus is an extinct species of hominid that lived throughout most of the Pleistocene geological epoch. The video mentions this species as having larger brains and being the first to migrate out of Africa, indicating a significant step in human evolution and the spread of human populations.

💡Neanderthals

Neanderthals are a species of archaic humans who lived in Eurasia. The script discusses their adaptations to cold climates, such as the creation of clothing, and their technological advancements, like the systematic use of fire and complex tool-making, which contributed to the diversity of human evolution.

💡Foraging

Foraging is the act of searching for food in one's environment. The video contrasts the lifestyle of early human foragers with that of agricultural societies, suggesting that foragers may have had a more leisurely and healthy existence, though with a potentially higher risk of violence.

💡Mt. Toba eruption

The Mt. Toba eruption refers to a supervolcanic event that occurred approximately 74,000 years ago in Sumatra. The script describes this event as a near-catastrophe for human populations, leading to a genetic bottleneck and a drastic reduction in population size.

💡Homo sapiens

Homo sapiens is the species to which all modern humans belong. The video discusses the emergence of Homo sapiens around 250,000 years ago and their development of complex tools, art, and culture, which are hallmarks of our species and our capacity for collective learning.

Highlights

The Planet of the Apes films are discussed as a metaphor for human evolution.

Primates evolved and dispersed from East Africa, influencing the Earth's development.

Humans are one of the most complex entities in the cosmos, according to the video.

The video emphasizes the importance of collective learning in human evolution.

Around 65 million years ago, the extinction of dinosaurs led to the rise of small shrew-like ancestors of humans.

Plate tectonics and the separation of continents influenced primate evolution.

The creation of the Himalayas by the collision of India and Eurasia is mentioned.

The divergence of the ape line from old-world monkeys occurred 25 to 30 million years ago.

Humans and chimpanzees share a common ancestor that split around seven million years ago.

Chimpanzees and humans exhibit similar social behaviors and aggression.

Bonobos, a close relative, display more peaceful and sexual behaviors to resolve conflicts.

Bipedalism in human ancestors evolved as a response to climate change and savanna environments.

Australopithecines, early hominids, were bipedal with small brains and used simple tools.

Homo habilis was the first to use stone tools for cutting, showing early technological advancement.

Homo ergaster introduced a variety of stone tools and may have used fire.

Collective learning is highlighted as a key factor in the development of human technology.

Early humans had a relatively short workday compared to later civilizations.

The debate between Thomas Hobbes and Jean-Jacques Rousseau on the nature of early human life is discussed.

The video concludes by emphasizing the importance of collective learning in human survival and innovation.

Transcripts

Hi, I'm John Green. Welcome to Crash Course Big History Project where today we're going

to talk about the Planet of the Apes films. - What's that? Apparently, those were not documentaries.

But there was an evolutionary process that saw primates move out of East Africa and transform

the earth into an actual planet of the apes...but the apes are us.

And then we made the movie and then some prequels and some sequels and some reboots and now sequels to the reboots.

Man, I can't wait until I get to see the 2018 reboot of this episode of Crash Course Big

History I hear they get James Franco to play me.

[Theme Music]

So we're about halfway through our series and after five episodes involving no humans

whatsoever today we are finally gonna get some people.

Mr. Green, Mr. Green! Why are we already at humanity, I mean if we're covering 13.8 billion

years shouldn't humanity come in like, the last two seconds of the last episode? I mean

humans are totally insignificant compared to the vastness of the universe, like we should

be checking in on how Jupiter's doing.

Fair point, Me From the Past; Jupiter by the way, still giant and gassy.

There's two reasons why we focus a little more on humanity in Big History; the selfish

reason is that we care about humans in Big History because we are humans. We are naturally

curious to figure out where we belong in the huge sequence of events beginning with the big bang.

Secondly, humans represent a really weird change in the universe. I mean, so far as we

know, we are one of the most complex things in the cosmos.

Whether you measure complexity in terms of biological and cultural building blocks or

networks or connections, I mean, we're kind of amazing! Now I realize that many of our

viewers will be offended by our human-centric bias, but humans are amazing. I mean, we invented

the internet and we invented animated GIF and we invented Dr. Who and then we invented

Tumblr, a place where all of these things can come together!

So 65 million years ago, catastrophe wiped out the dinosaurs and we saw the adaptive

radiation of a tiny shrew-like ancestor of humans that would look more at home like,

next to a hamster wheel than in your family album. Let's set the stage in the Thought Bubble.

So the slow waltz of plate tectonics continued to pull Eurasia and the Americas apart expanding

the Atlantic Ocean, primates colonized the Americas, and separated by the vast Atlantic, continued

their separate evolution into the new world monkeys -- which is not a band name, although it should be.

Then around 45 million years ago, Australia split from Antarctica and while mammals out-competed

most marsupials in the Americas (except animals like possums), Australia saw an adaptive radiation

of marsupials. This, of course, meant that later, one-hundred thousand years ago when

the Americas were having their share of mammoths and saber-tooth tigers, Australia was having

a spell of gigantic kangaroos, marsupial lions, and wombats the size of hippos.

Then, somewhere around forty million years ago, India, which had been floating around

the southern oceans as an island, smashed into the Eurasian continent with such force

that it created the world's tallest mountain range, the Himalayas.

Meanwhile, in Africa, Primates continued to evolve and twenty-five to thirty million years

ago, the line of the apes diverged from theold-world monkeys and no, neither you, nor a chimp,

is a monkey, nor did we evolve from the monkeys that are around today - those are like our cousins.

Moreover, we did not evolve from chimpanzees, the chimpanzee is a cousin as well, not an

uncle. We are not more highly evolved than they are; Instead, our lines of descent split

off from a common ancestor with chimpanzees about seven million years ago. Then chimpanzees

further split into a separate species, the Bonobos. Knowing about this common ancestry

tells us a lot about our shared traits with other primates.

For instance, we all have fairly large brains, relative to our body mass, we have our eyes

in the front of our heads from the days when we hung out in trees and depth perception

was an excellent way of telling how far away the next tree branch was so as to prevent

us from plummeting to our deaths, and we also have grasping hands, to make sure, you know,

that you could hold onto the branch in question. Primates also have hierarchies, social orders

whether male or female led, that determine who gets primary access to food, mates, and other benefits.

Thanks Thought Bubble! So, our closest evolutionary cousins, the chimpanzees, can tell us a thing

or two about shared behaviors. For one thing, while all primates have a hierarchy of alphas

and betas, humans and chimps, who share 98.4% of their DNA, are the most prone to team up

together and launch a revolution against the alpha male. We're also both prone to ganging

up, roaming our territory, and beating up unsuspecting foreigners of the same species,

and not for direct survival reasons.

Chimpanzees have been observed finding a lone chimp male from another group and kicking,

hitting, and tearing off bits of his body and then leaving the helpless victim to die

of his wounds, and humans definitely bear this stamp of our lowly origin, where indeed,

the imperfect step-by-step process of evolution made us highly intelligent, but still, with

prefrontal cortex's too small, and adrenal glands maybe too big.

Aggression and blood lust are definitely part of our shared heritage, and, looking at more

recent human history, does that really surprise anyone? Contrast that behavior, for a moment,

with the more peaceful Bonobos, who are female-led, and when a male in her group gets a bit pushy,

the females are prone to gang up and teach him a lesson. When it comes to inter-group

encounters in the wild, the male Bonobos seem tense around strangers at first, until usually,

the females from each group cross over and just have sex with the newcomers, completely diffusing

the tension. Talk about make love, not war - Bonobos are hippies.

While our common ancestor with chimpanzees around seven million years ago was more suited

to living in forests and seeking refuge from danger by climbing trees, climate change in

East Africa made things colder and drier, and many forests were replaced by woodlands

and wide-open savanna. Life in the savanna meant our ancestors needed to run from predators

rather than climbing trees, so our line shifted away from the bow-legged stance reminiscent

of chimpanzees, and developed bipedalism, where our locomotion came from legs that were

straight and forward-facing.

There's still some debate about when bipedalism first began, but we know that by the first

australopithecines around four million years ago, our evolutionary line was bipedal, this

also freed up our hands.

Australopithecines were not very tall, standing only just above a meter, or just above 3.5

feet, and had brains only a little bigger than modern chimpanzees. They were largely

herbivores with teeth adapted for grinding tough fruits and leaves. Australopithecines

may have communicated through gestures and primitive sounds, but their higher larynx

meant that they couldn't make the range of sounds required for complex language. There

was probably a lot of pointing and grunting going on. Kinda like me, before 6 am.

By 2.3 million years ago, homo habilis arrived on the scene. They weren't much taller than

australopithecines, but they had significantly larger brains - though still a lot smaller

than later species. Excitingly, homo habilis is known to have hit flakes off of stones

to use them for cutting. Now, lots of species use tools, for instance chimpanzees use sticks

for fishing termites out of the ground, they use rock hammers and leaf sponges and branch

levers and banana leaf umbrellas. A lot of these skills don't seem to arise spontaneously,

just because of the intelligence of individuals, but, like in the case of termite fishing,

chimpanzees pass the information on by imitation - primate see, primate do.

In a way, this social learning is sort of cultural, yet, succeeding generations of chimpanzees

don't accumulate information, tinker with it, and improve upon it, so that after 100

years, chimpanzees are owners of highly efficient and wealthy termite fishing corporations.

Similarly, as impressive as homo habilis stone-working abilities are, we see very little sign of

technological improvement over the thousands and thousands of years that habilis existed.

Same goes for homo ergaster erectus, who was around 1.9 million years ago.

Homo ergaster erectus had an even bigger brain, was taller, and they even seemed intelligent

and adaptable enough to move into different environments across the old world. They may

have even begun our first clumsy attempts at fire, which is vital for cooking meat and

vegetables, opening up opportunities for more energy and even more brain growth.

But still, there's not much sign of technological improvement, their tools got the job done,

if it ain't broke, don't fix it.

Yet 1.78 million years ago, we do see homo ergaster creating a wide new range of teardrop

hand axes in Kenya. By one-point-five 1.5 million years ago, these teardrop axes had

rapidly become common, and had improved in quality and were shaped with a flat edge into

multi-purpose picks, cleavers, and so forth.

Archaeologists see this as the first possible sign of tinkering and improvement of technology

that may have been transmitted by social learning. A faint glimmer of something new. Why is this important?

Well, humans didn't get to where we are because we're super-geniuses. It's

not like invented the Xbox One out of the blue one day, it was an improvement upon the

Xbox 360 which was an improvement upon earlier consoles, arcade machines, computers, and

backward onto the dawn of video games. In the same way, we didn't just invent our

modern society by sudden inspiration, it's the result of 250,000 years of tinkering and

improvement. This is where accumulation matters - it's called collective learning, the ability

of a species to retain more information with one generation than is lost by the next. This

is what has taken us, in a few thousand years, from stone tools to rocket engines to being

able to have the Crash Course theme song as your ringtone. Progress!

If there was collective learning in homo ergaster, it was very slow and very slight. This may

have been due to limitations on communication, abstract thought, group size, or just plain

brain power. But over the next two million years, things started to pick up. Homo antecessor,

Homo Heidelbergensis and the Neanderthals developed the first systematically controlled

use of fire in hearths, the first blade tools, the earliest wooden spears, the earliest use

of composite tools, where stone was fastened to wood, all before homo sapiens were ever

heard of, around 250,000 years ago.

Neanderthals even moved into colder climates, where they were compelled to invent clothing,

they used complex tool-manufacture to produce sharp points and scrapers and hand-axes and

wood handles, and they improved their craft over time.

While evolution by natural selection is a sort of learning mechanism that allows a species

to adapt generation after generation, with a lot of trial and error, and death - collective

learning allows for tinkering, adaptation, and improvement on a much faster scale with

each generation and across generations without waiting for your genes to catch up.

Anatomically similar homo sapiens have been around for about 250,000 years, and throughout

that time, we've been expanding our toolkit from stone tools to shell fishing to trade

and actual fishing, mining, and by 40,000 years ago we had art, including cave images,

decorative beads and other forms of jewelry, and even the world's oldest known musical

instruments - flutes carved from mammoth ivory and bird bones.

All this stuff came about as a result of collective learning. As long as you have a population

of potential innovators, who can keep dreaming up new ideas and remembering old ones and an

opportunity for those old innovators to pass their ideas onto others, you're likely to

have some technological progress.

These mechanisms are still working today - we've got over seven billion potential innovators on

this planet, and almost instantaneous communication, allowing us to do so many marvelous things

including teach you about Big History on the internet.

So life for early humans was pretty good, like foraging didn't require particularly

long hours - the average work day for a forager was about 6.5 hours. When you compare that

to an average of 9.5 hours for a peasant farmer in medieval Europe, or the average of nine

hours for a typical office worker today, foraging seems downright leisurely.

Quick aside: I work thirty minutes a day less than a peasant farmer in medieval Europe?

That's not progress! Stan, I want more time off!

Stan just pointed out that I have a chair, something that peasant farmers in medieval

Europe did not enjoy, and I want to say that I'm very grateful for my chair.

Thank you for my chair, Stan.

Anyway, a forager would go out, hunt or gather, come home, eat, spend time with the family,

dance, sing, tell stories, and foragers were also always on the move, which made it less

likely that they'd contaminate their water, or sit around waiting for a plague to develop.

And with their constant walking and their varied diet, foragers were in many ways healthier

than the peasants of ancient civilizations. There were also, in some ways, healthier than

us, but we have antibiotics for now, so we live longer, for now.

The classic view of foraging life is best described by Thomas Hobbes, who wrote:

"No arts, no letters, no society, and which is worst of all continual fear and danger

of violent death and the life of man, solitary, poor, nasty, brutish, and short."

Except, not really. I mean, life for the average person in twelfth century France was also

a smidge nasty, brutish, and short, and the lack of wealth disparity in foraging cultures

may imply greater equality between social rankings and even between the genders since

female gatherers appear to be responsible for the majority of food collected, rather

than the hunting males. And from that perspective, life was kind of ruined by the advent of agriculture

and then, later, with states, as Jean-Jacques Rousseau said,

"The first person, who having enclosed a plot of land, took it into his head to say, 'this

is mine' and found people simple enough to believe him, was the true founder of civil

society. What crimes, wars, murders, what miseries and horrors would the human race

have spared, had someone pulled up the stakes or filled in the ditch and cried out to his

fellow men: 'do not listen to this imposter, you are lost if you forget that the fruits of the

Earth belong to all, and the Earth to no one'"

and thus summarizes one of the great debates in the world of political science. Man, Big

History discusses everything! Now, it's possible that neither Rousseau nor Hobbes was completely

correct, and that, like, private property and agriculture didn't create the glory days or end them.

Like, as previous mentioned, all primates have a dominance hierarchy of some kind. Also,

you don't need a wealth disparity to drive human beings to hurt each other - like, surveys

of excavated remains from the paleolithic indicate a murder rate that was possibly as

high as ten percent. Now, those statistics are still disputed, but despite the relatively

short work day, life in the paleolithic sounds a lot less appealing when you consider the

high murder rate, and also, the occasional infanticide. That's not even to mention the

old or disabled people who, when they couldn't keep up anymore, were abandoned to die in

the wild. I can't help but feel that I might not have thrived in the paleolithic what with

my visual impairment and general lack of interest in hunting.

Anyway, we call this the Hobbes vs. Rousseau debate, and it's still unresolved. I mean,

humans may have been corrupted in many ways by society, on the other hand, it's possible

a lot of the crimes and follies of human history may just be symptoms of our coping with the

bad wiring left to us by evolution.

You know, humans are a bit of an obsolete machine, we aren't particularly well-suited

to the many lifestyle changes that have happened in the past few thousand years - faster than

our genes can keep pace with. But how you interpret the lives of early human foragers

largely determines your view of history and also the fundamental nature of the human character.

Ask yourself which side you sit on: Is humanity fundamentally good and corrupted by technology

and modern social orders, or are we fundamentally flawed and in need of some sort of structure

and authority? Or is there some kind of both/and way of addressing the question? Here at Crash Course,

we don't have answers, but we are grateful that you're pondering these questions with us.

In any case, collective learning was really good for our survival, but then, 74,000 years

ago, disaster struck. A super-eruption at Mt. Toba on the island of Sumatra in present-day

Indonesia clouded the skies with ash and cooled the climate. Plants and animals, a.k.a. food, died

off and genetics studies showed that this reduced the human population to a few thousand

people. So as a result of this, we aren't exactly inbred, but there's more genetic diversity

between two of the major groups of chimpanzees in Africa than there is in all of humanity.

So this small group heroically recovered and spread out of Africa 64,000 years ago, colonizing

diverse environments and continuing to innovate. For 13.8 billion years since the beginning

of the universe, complexity had been rising in a powerful crescendo, but in the space

of a few millennia, collective learning was about to make things really bonkers.

More on that next time.