History and prehistory발음듣기
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History and prehistory
107문장
100% 한국어
번역 7명 참여
출처 : 칸아카데미
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[Instructor] Anatomically modern human beings have been on this planet for roughly 200,000 years.발음듣기
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And even though that's a small fraction of the amount of time the Earth has been around which is over four billion years on a human scale it's an incredibly long amount of time.발음듣기
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Just to put it in perspective, if this is present time if you wanted to put, when was the Roman Empire?발음듣기
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Well if we're talking about 2000 years ago it would show up on our timeline right about there.발음듣기
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If you wanted to talk about when the pyramids were constructed it would be right about there.발음듣기
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If you want to see how long we've had writing about 5000 years is our current best estimate.발음듣기
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Another way to think about it think about all of our ancestors the various generations that have passed since the first appearance of anatomically modern human beings.발음듣기
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It might be a founding of a village a killing of an animal, a very simple courtship a tenderness between a mother and their child.발음듣기
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It's hard for us to imagine how much has occurred even in the last 100 or 200 or thousand years much less 200,000 years.발음듣기
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And if we want to get a little bit more technical we can also think about pre-history, which is, technically the things that happened before we had writing.발음듣기
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But even when you have writing, it's not enough as we'll see not only in this video but in many videos as we study history and world history.발음듣기
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It's really a lot of science and a lot of detective work to make sense of what has happened.발음듣기
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For example, we didn't know what these hieroglyphs said until 1799 when we found the Rosetta Stone.발음듣기
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And what was useful about the Rosetta Stone is that they had some text written in the hieroglyphs.발음듣기
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And they had the same text then written in a Greek that we were able to understand and that started to help unlock what these hieroglyphs said.발음듣기
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But even once you have a sense of what they say or even if you understand it quite well you still have to do a lot of detective work and take everything with a grain of salt.발음듣기
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You can imagine if there's a bunch of groups of people here and we get the history from this group for some reason we were able to find what they wrote well it might not be completely unbiased.발음듣기
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At the extreme form, they might have eliminated some of these groups and then only they were around to say what actually happened.발음듣기
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You also have to be skeptical because you don't know whether these stories are actual accounts or whether someone just made it up to fit a worldview.발음듣기
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You also have to keep in mind that these stories whether they were transmitted written or orally they're oftentimes retransmitted from generation to generation, especially in the oral case.발음듣기
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Even when we have it, obviously we have much more writing as we get to the more recent past we have to be very very skeptical.발음듣기
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We know, today even if two observers observe something yesterday something that just happened, they might have very different perceptions of what happened.발음듣기
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But things get, in some ways, even more interesting before we have writing, when we go into pre-history.발음듣기
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You might wonder how do we know anything about what happened if there's no written accounts?발음듣기
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And the type of people, the sciences that will study this you'll hear terms like anthropologists.발음듣기
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And then a subset of anthropology which is really delving into pre-history and even history itself, is archaeology.발음듣기
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Archaeology which is the subset of anthropology that focuses on the past study of humans and human society and they're mainly going to do it through remains.발음듣기
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Now there's other fields, you might associate the field of paleontologist. Paleontologist. Paleontology.발음듣기
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You might associate this with things like dinosaur bones but their techniques are also useful for old human remains or even pre-human remains.발음듣기
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They will use some science in order to figure out when did this skull enter into the ground?발음듣기
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Radiocarbon dating which could be used for things up to around 50,000 years old so around that time span on our timeline.발음듣기
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That gets between interactions with the solar wind and these cosmic particles becomes this radioactive carbon 14.발음듣기
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And the carbon 14 which can become part of carbon dioxide incorporate into plants through photosynthesis which then get eaten into animals.발음듣기
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And it takes roughly 5,000 years, 5,730 years to be exact for roughly half of the carbon 14 to decay into carbon 12.발음듣기
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So based on this ratio and I go into much more detail in other videos you can figure out how old these things are and you get reasonably precise within a couple of a hundred, hundreds of years.발음듣기
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If you want to go further into the past there's things like potassium-argon dating which is once again taking a radioactive form of potassium and using the idea that it decays into argon.발음듣기
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And that when a volcano releases the argon in that rock is able to go into the atmosphere, but then once it hardens you have the decay and so you can see how long since that volcanic eruption are we looking at.발음듣기
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Say, "Okay, this is that, a certain amount of age, "that is a certain amount of age, this was volcanic rock from a volcanic eruption."발음듣기
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You can say, "Okay, a fossil that I found here is going to be newer than the stuff here and it's gonna be older than the stuff here and this might be the newest of all."발음듣기
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So you can look at relative dating and if you're lucky enough to have some volcanic rock you could do some of this potassium-argon dating and there's many many other techniques.발음듣기
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And it isn't just about saying, "Oh, this skull was in this place in the world at this time."발음듣기
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You might have some trauma fractures here and you might say, "Okay, that was a violent death."발음듣기
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You might look at their teeth to think about the type of things they might have eaten or their general health.발음듣기
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This right over here, these are Paleolithic arrow I guess, spearheads or tools right over here.발음듣기
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And by looking at all of that you have all of these scientists, you have these anthropologists, archaeologists, paleontologists who are starting to piece together pre-history.발음듣기
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Sometimes we have writing and we have these technique to try to get a more complete picture.발음듣기
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Even though we have all of these techniques we're learning more everyday, our understanding of all that has happened is very incomplete.발음듣기
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There are things that very serious people believed 50 or 100 years ago that we have now proven to be false.발음듣기
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And things that we now take very seriously it's likely that in 50 or 100 years people might prove some of that wrong.발음듣기
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