Name: 人類進化。Crash Course Big History #6 (Human Evolution: Crash Course Big History #6)
Uploaded: 2021-01-14T06:34:37.000Z
Duration: 16 min 14 s
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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.

關係子句

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.

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

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,

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

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

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.