Subtitles section Play video Print subtitles Hi, I'm John Green. Welcome to Crash Course Big History 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. So we're about halfway through our series, and after five episodes involving no humans whatsoever, today we are finally going to 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 the last, like, 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 the animated GIF and we inventedDr. 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. Primate 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, about 100,000 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 40 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 25 million to 30 million years ago, the line of the apes diverged from the Old 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 7 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 on to 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 cortexes too small and adrenal glands maybe too big. Aggression and bloodlust 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 a group gets a bit pushy, the females are prone to gang up and teach him a lesson. When it comes to intergroup 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 the chimpanzees around 7 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 in wide-open savannah. Life in the savannah meant our ancestors needed to run from predators rather than climbing trees, so our lines 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 4 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 over three and a half 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, kind of like me before 6:00 a.m. By 2.3 million years ago,Homo habilisarrived 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 habilisis known to have hit flakes off of stones to use them for cutting.