Humanity on Earth
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Human Evolution Overview
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Understanding Calendar Notation
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Correction Calendar Notation
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Development of Agriculture and Writing
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Firestick Farming
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Collective Learning
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Thomas Malthus and Population Growth
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Land Productivity Limiting Human Population
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Energy Inputs for Tilling a Hectare of Land
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Random Predictions for 2060
Human Evolution Overview From the extinction of the dinosaurs to humanity
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- If we were to rewind the clock back about 70 million years
- You would see dinosaurs roaming the earth,
- and this is a very nice picture here of a dinosaur
- enjoying a sunset at the beach.
- But unfortunately for the dinosaurs, about 65 million years ago
- we believe that a huge meteorite struck the earth
- and essentially wiped out the dinosaurs.
- And it probably wiped out a bunch of other species with it,
- because, you can imagine the shock wave itself
- would just exterminate tons of species
- then you would have the tsunami of unimaginable size, that would just envelope the continents
- for some period of time, then you would have the soot
- that would go into the air and maybe, make it impossible for most of the plant species
- to live, because it would be blocking out all of the sunlight
- And so in an environment like that, we could imagine that an animal like this
- would be well suited to survive
- It's sitting there underground
- maybe it can hibernate in some way so it doesn't need food for long periods of time
- maybe it has its own food stash under there some place
- And so we believe that our
- Ancient, ancient, ancient
- Ancient
- ancient ancestors, after this mass extinction event
- might have been something like this
- kind of a mole-looking, rodent animal
- that was protected from all of this craziness
- that was happening on the surface
- because they like to hang out underground and
- you know, have all of their food nearby them
- and maybe they could hibernate in some way
- So you can imagine that once everything settled down
- and now we're talking hundreds of years,
- thousands of years,
- even MILLIONS of years,
- some of this guys' descendants start to poke their head out of the ground
- and are like. You know what? There's food in trees
- and there's no one else in the trees
- and trees are a good place to maybe a get away from
- some of the other predators
- that have managed to survive this mass-extinction event.
- And some of its ancestors, or some of its descendants I should say
- that were good at climbing trees
- decided, Hey! Let's try this tree thing out
- And so you started to have some selection for the descendants
- of this rodent that could climb trees well
- they were able to find food where their ancestors couldn't
- they could find protection in the trees where their ancestors couldn't
- So you could imagine, that some subset of this guys'
- descendants evolved into something that might have looked
- like this guy.
- And all of the pictures I'm showing you
- these are of modern animals, except for of course, the dinosaur
- I'm sure it's just kind of photoshopped in, in some way
- This is a modern Bush Baby, but I show this picture because
- it could have been what some of the primitive primates look like.
- Because a Bush Baby, it kinda climbs trees; it's able, it kinda looks like
- it's able to get a hand here, to start climbing the trees
- but it also has rodent-like qualities.
- But this of course a modern version of it, so
- This Bush Baby's ancient, ancient, ancient ancestor might have been
- that primitive primate, or that species of that primitive primate
- that was a descendant of rodents, that said "Hey let's see if we can climb these trees and find some food"
- And then some of its descendants might have had just
- the right adaptations, found their own little niche in the right ecosystems,
- and they would have evolved into monkeys
- once again, this is a modern monkey; so you could imagine
- a kind of primitive monkey.
- And then, some of those primitive monkey's descendants
- they turn into these modern monkeys eventually
- but some of them they grow larger in size,
- they spend more time outside of trees,
- they lose their tail, they don't need it as much for balance
- maybe it's actually a bad thing to have, because someone else could grab it
- when you're in a fight or something like that
- and they evolve into apes.
- And in particular the Great Apes
- So, one of the Great Apes
- The Great Apes involve Gorillas
- and Chimpanzees
- and the ancestor, or really the Great Apes also include Humanity
- So let me just review back on this timeline,
- just so we don't get confused,
- I'll review what we just talked about.
- So before this mass-extinction event 65 million years ago,
- you had all these types of species here
- maybe this right up here, maybe this was
- actually if I'm talking about species,
- maybe this was Tyrannosaurus Rex
- because the dinosaurs involved a whole bunch of - -
- so this might have been T. Rex,
- and I mean there's a bunch of species we could list over here,
- but after that mass-extinction event
- that was an endpoint for a ton, for a ton of species
- except for maybe this primitive rodent mole-like thing,
- that was, you know, maybe a lot of them died in this event,
- but just enough of them survived because they were underground,
- or just in the right place, or in a mountain or someplace
- who knows where they were?
- And some of them were able to evolve into
- primitive primates
- And some of those primitive primates,
- and this is once again pictures of primitive primates;
- and when I say primitive, these are modern versions of them
- so primitive doesn't necessarily mean worse,
- because obviously these guys were able to find, even in today's world, a niche for themselves
- they are able to find food and reproduce, and,
- in ways, that, you know, don't get in the way of ther people
- and other people don't get in the way of them
- When I talk about primitive primates
- I'm just talking about a kind of ancestral primates,
- maybe something that's not there, uh, today
- Although maybe some of it's descendants look very much like it.
- But anyway, some of those primates evolve into primitive monkeys,
- some of those primitive monkey's descendants become modern monkeys
- so this is, I'll call it M. Monkeys
- for modern monkeys,
- and some of them evolve into primitive apes
- and apes, their distinctive characteristic is that they are like monkeys
- but they don't have tails, and they are larger than most monkeys
- And so these primitive apes, some of their descendants are modern Gorillas
- at some point they break off, some of these descendants are a
- ancestor of both modern Chimpanzees and of human beings
- And we think, just looking at the DNA evidence
- We think that this departure right here, and the fossil evidence
- was about 7 million years ago
- That's our best guess for when we as human beings had
- a common ancestor with the chimpanzees.
- Now you have that common ancestor,
- some of that common ancestor's descendants became modern chimpanzees
- and some of them, maybe they explored the right ecosystem
- where it was more advantageous to do so,
- started to walk on two legs.
- And the most famous fossil of this
- is the Australopithecine Fossil of Lucy
- that was discovered 3.2 mil --, it was discovered more recently
- it's 3.2 million years old.
- So the whole Genus, and Genus is kind of one level of categorization above Species.
- The whole Genus of Australopithecine, these were 4 million to 2 million years ago
- 4 to 2, and we never know
- you could always find a fossil that is older than this
- maybe newer than this
- I've read one account that said maybe 1 million years ago
- but give or take, the Lucy Fossil,
- which is the most well-established Australopithecine Fossil
- is about 3 million years old
- And this is a reconstruction I have
- over here of Lucy.
- So this is probably what Lucy looked like.
- And once again, there were many Lucys
- it wasn't just there was one Lucy and we're all descendant from Lucy,
- and it's actually not even clear that we are even descendant
- directly from Australopithecine, we might be a cousin
- we might be a cousin species
- or a cousin Genus, I should say
- Genus is the category right above Species
- So if you fast-forward a little bit more
- you go to about 2.3 to 1.4 million years ago
- 2.3 to 1.4 million years ago
- we see fossils that they are standing upright,
- the brain size is bigger, because if you look at the
- Australopithecine Fossils, they are standing upright, but their cranial capacity isn't that
- different than Chimpanzees.
- You fast-forward to 2.3 million to 1.4 million years ago
- we start to see fossils where
- they are standing upright still
- and the cranial capacity has grown,
- and you're starting to see primitive stone tools around the bone fossils
- and so, we believe that this is, these are
- one of the first, so this is really just how we categorize it
- but these are some of the first fossils that we categorize as belonging to the same Genus as ours
- and the Genus is Homo
- And Homo just means man
- so it's the group right above Species of Man
- and we call them similar to man,
- because it looks like they are starting to make primitive stone tools,
- they stand upright like us,
- and they have larger cranial capacities than the Australopithecine Fossils or modern Chimpanzees.
- And once again, we never know if Homo Habilis, which
- literally means, the Homo part means Man,
- Habilis means Handy, because he liked to make tools or whatever else.
- We don't if Homo Habilis is a descendant of Lucy's Species,
- of Australopithecus, or maybe a cousin species
- maybe they are both descendants from a common ancestor
- we're not quite sure.
- Then you fast-forward a little bit more
- we're talking now about 1.8,
- so now we're talking about 1.8 million to 1.3 million years ago
- and we start seeing fossils where the cranial capacity larger than Homo Habilis,
- getting closer in size to kind of what we know,
- what our notion is of kind of a modern person's cranial capacity,
- at least relative to body size,
- and this is Homo Erectus.
- And once again, we don't know if Homo Erectus is the descendant of Homo Hibilus,
- maybe they have a common ancestor,
- who knows?
- It looks from the fossil evidence that there was,
- especially when you look at this range here
- that there was some overlap, where you had
- both Homo Erectus and Homo Hibilus living on the same planet at the same time
- Now you fast-forward even more,
- and we think, about 600,000 to 300,000
- once again, all of these are constantly being modified
- as we get better at finding new fossils, or interpreting the fossils we have,
- or we look at DNA evidence or whatever
- about 600,000 to 300,000 years ago, you have the Neanderthals appear
- And Neanderthals are in the same Genus as Humans,
- so it's really Homo Neanderthalensis.
- I always have trouble saying that,
- so this is still part of Homo.
- And a common misconception is that the Neanderthals
- are somehow a more primitive version of humans,
- that they are somehow cavemen and we are modern men
- That's not the case.
- The belief is that Neanderthals are either a cousin species, we have a common ancestor
- or, that they're actually a sub-species of human beings
- and there is some belief that they might have interbred with Homo Sapiens,
- and maybe some, or a good number of us have Neanderthal genes.
- It's nothing to be ashamed of, it's just something, you know, unfortunately that Neanderthals
- just get a bad name, because of our popular culture.
- If anything, so this is a drawing of Neanderthal brain, they actually had a
- fairly large cranial capacity, although scientists say
- they kind of make one reason or another why we think they might have been more
- primitive than Homo Sapiens, but who knows? We don't know.
- We're constantly learning things every day.
- But of course, the whole point of this is to talk about
- how humans showed up on this planet,
- and the first really human fossils we find about 200,000 years ago
- and this, remember, we're in the Genus Homo;
- and now we've finally found something that looks just like us
- anatomically at least, we can't study its behavior and all the rest,
- and now we get to Homo Sapiens,
- the Homo part, once again, means Man
- and the Sapiens, the Sapiens means "Thinking".
- So we can debate whether it's an appropriate title for our Species,
- but it's Thinking Man,
- so once again the Neanderthals they were either a cousin species
- for a lot of this time, especially once Homo Sapiens showed up,
- and maybe Homo Sapiens showed up before this, we just haven't found the fossils yet
- They were maybe both inhabiting the same planet,
- maybe there was some interbreeding,
- but the Neanderthals disappeared about 30,000 years ago
- 30,000 years ago these guys disappeared
- Maybe some of them kind of got mixed in with the Homo Sapiens
- started to interbreed with them,
- or they might have just been killed off,
- because they were fighting over the same ecosystems
- and I have made a little sample here of Homo Sapiens
- just in case, well, I'm assuming most of you watching this video are one
- but just in case, here's my little sample
- We can debate how representative of a sample of our species this really is.
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
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