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宇宙学和天文学
课程: 宇宙学和天文学 > 单元 4
课程 2: 人类的进化史农业以及写作的发展
新石器时代和旧石器时代. 由 Sal Khan 创建
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in this video I'm gonna use words like eras periods periods and ages to refer to segments of time in in in the human or in the pre human past and what I want to clarify right from the get-go because frankly this is something that's confused me in the past is that peat archaeologists will refer to eras periods and ages in a human past and they're usually referring to periods of tens of thousands of years or thousands of years but these are different eras periods and ages than the ones that geologists would refer to when they're talking about geological time in geological time era means several hundred millions of years periods and ages mean millions of years when a archaeologist when we're starting when we're starting the human past this is just talking they're just generally talking about long segments of human time but not in the millions of years usually in the thousands or the ten thousands of years so what I want to do with that out of the way is talk about what has happened in the the distant human past or the distant pre-human past and also touch on some of the classic classifications for these segments of time because they they actually tell us what were the interesting developments that happened to humanity over over the two hundred thousand years over the two hundred thousand years that homo sapiens have been on this planet or that we believe that homo sapiens have been on this planet so the longest period of time in human past or the category of human time in there's different ways you can categorize it is the Paleolithic era right over here paleo Paleolithic Paleolithic era and what really makes that period of time so this is this begins even in prehistory or pre human history so before we before Homo sapiens even existed you have the beginning of the Paleolithic era that really began with the development of stone tools and as we learned in the video on human evolution there were pre Homo sapiens species that were using stone tools and so the Paleolithic era it's really kind of signified by one the stone tools but even more that either either the pre humans or once you know you go about 200 thousand years ago humans show up it's it's kind of distinguished by humans being hunter-gatherers hunter-gatherers which essentially means to survive we used to walk around a lot you know if we couldn't see something obvious to hunt maybe maybe a wooly mammoth or something if we didn't see something obvious to hunt we would look around for snails or mushrooms or whatever else and and that's how we would survive that's how we would live and because we were constantly adapting to our environment based on the seasons we were maybe following animals as they migrated hunter-gatherers were fundamentally nomadic which essentially which means that they never settled in one place for a long time they they were always ready to kind of pick up probably their tents and follow the herd or follow whatever animals they were hunting or or follow the season so they could go to warmer climates maybe where there's more likely to to find something to find on the ground to eat maybe during the winter who knows and so the Paleolithic era is really distinguished by that it's a huge swath of time in in in human history and it doesn't come to an end until you get to the advent of farming so the Paleolithic era I mean we're literally talking about over two million years ago is when it starts before Homo sapiens even existed as a species and it goes all the way to the advent of harming that we believe first came about around 11,000 to 7,000 years ago and this abbreviation right here this BP this does not stand for a british petroleum it stands for before present or before the present time so one more acronym to kind of have in your toolkit when you see things and obviously if we're eleven thousand years before the present that's the same thing as nine thousand years before Christ or before the Common Era because Christ was we believe born 2,000 years ago now it may or may not be obvious to you but the advent of Agriculture is a super big deal arguably the biggest deal and the development of human civilization or in all of human history and you might say hey you know what's the big deal about agriculture these these characters over here look look pretty happy they're able to walk around a lot they're able to hunt you know what's the big deal of all of a sudden people plowing fields and and domesticating cattle and and having chickens to lay eggs and whatever else and the big deal about that besides the fact that it would change people's diet is it for the first time it allowed them to not be nomadic it allowed them to and you could have probably had some hunters who who were somewhat settled may be living near the ocean maybe they did some fishing and all the rest but for the most part with the development of Agriculture it forced people to stay in one place so you have the Paleolithic era all the way all the way to the advent of Agriculture which was about eleven thousand to seven thousand years ago and besides the fact that it changed people's diet it allowed them to settle so agriculture agriculture allowed human beings to settle down in one area and it wasn't just that they were settling in one area but because they were able to control their environment they were able to increase the density of things of of crops that humans could consume in animals that humans can consume and lower the density of crops that humans can't consume and that animals can't and animals that they can't consume or that they don't want around like you know pests of some type what it allowed them to do is also settle in more dense environments you can imagine when you just have people walking around you need a lot of land to support even the calorie requirements of one human being but all of a sudden if you are able to develop agriculture you're able to domesticate animals all of a sudden you could have in the same amount of land you can have more calories being generated and because you have more calories being generated in a smaller amount of land you can people can settle and they can settle in a denser environment and so agriculture was really this necessary requirement for people to kind of develop civilization or to develop villages to develop villages and cities and maybe also giving them for the free time to start thinking about hey maybe we want to think about how we can record what we know how we can develop even more technologies and so just to give us a sense of the the categorization that an archaeologist would use for these different periods of time I told you we start with the Paleolithic era with the advent of stone tools pre humans most of human time on this planet and then about 11,000 years ago the development of agriculture and it developed independently at different places around the world which is by itself an interesting phenomenon and people think that it might just be that the the climate might have warmed up a little bit so that people may be naturally there were some some human edible crops that were existed in a little bit of a denser environment and humans learned to optimize that slowly and they did that independently but it's an interesting question of why did it develop just then after a hundred and you know eighty a hundred ninety thousand years why did agriculture all of a sudden happen but just to get the terminology the Paleolithic era is that period before agriculture and then once agriculture starts developing we are now in the Neolithic we are now in the Neolithic era and some archaeologists will describe a transition period between the Paleolithic and the Neolithic era called the Mesolithic and just so you know what these words mean because they actually makes sense when you know what they mean paleo paleo means old means old and lithic means stone or of stones so they're really talking about the Old Stone Age Neolithic as you can imagine means new new stone so it's kind of the new Stone Age and meso means middle so it is the middle it is the middle Stone Age so another way of thinking about this whole period from when people were hunter-gatherers all the way to about eleven eleven thousand to seven thousand years ago when they develop agriculture this whole period is called the Stone Age and the Stone Age is is kind of this biggest age and there's just different ways of describing it because if you just call the Stone Age you're really making importance out of the actual tools that were people that that you know that people could shape they weren't able to use metal at this point when you refer to Paleolithic and Neolithic you're really you're maybe referring a little bit more and there's other ways to think about it but you're referring a little bit more to the lifestyles of the human beings Paleolithic being hunter-gatherers Neolithic I have being actually settled having actually started to develop kind of primitive villages and even cities and then of course methyl Issyk methyl lithium Mesolithic is in between and just for our kind of a pop culture reference you might have heard of the Paleolithic diet that people some people are going on now and those are people who try to live like hunter-gatherers their belief is that most of human evolution occurred while we were hunter-gatherers and so that's what our bodies are most accustomed to so they like to eat meat and they like to eat a lot of nuts and I even met at a co-worker once who used to only eat raw meat and I don't know if that is even justified or that's even somehow validated by the archaeological record these people probably did cook their meat now at the end of the Stone Age we would have I would say the number two most significant development in human history and now we're talking about 3000 BC which is about five thousand years ago and this is the development of writing so we were hunter-gatherers about nine to ten thousand eleven thousand years ago people start developing agriculture allows them to settle in more dense environments it also gives them a little bit more free time because they don't have to hunt and gather all the time and then you go and once again we'll probably discover things as we go forward in time that maybe these dates need to be pushed back or whatever else we discover new civilizations or who knows but our best sense is you have these villages you have these civilizations developing and by about five thousand years ago so this would be five thousand before the present or three thousand BC before Christ you have people saying hey why don't we start trying to write down what we know so it doesn't so that you know when I tell someone orally it doesn't actually lose information there and that so our descendants can slowly collect all of the knowledge we have and maybe accelerate you know I don't know if they did it explicitly thinking of these but let's just write down what we know and so at about that period of time you have as far as we can tell the first development of kind of a pictogram based system of writing and the earliest system of writing we know is cuneiform which is from the Sumerian civilization which is now in with present-day Iraq and what's the really big deal about this is that this is on some level the beginning of recorded history we could talk about the word history you could say the history is all of the past and we could use the arkla archaeological record to figure out stuff before people started to write things down but when they started to write things down now it was recorded now we're actually getting actual accounts of what people know of actual people's knowledge and the reason why this is a big deal I mean agriculture hopefully you now appreciate that that it was a pretty big deal but the reason why why writing was a big deal is that now civilization could collect its knowledge and it could it could build upon it generation after generation without having to worry about people forgetting it or or information getting distorted verbally from from from ancestor to descendant and with that you also have the beginning of the Bronze Age and the Bronze Age is kind of known for this beginning of even though it's referring to a material which comes from the first time that people started using bronze as a tool or using bronze for their tools and further weapons and bronze just you know it's a mixture of mostly copper and a little bit of tin but the Bronze Age and at least in my mind the biggest deal of what started at the beginning of the Bronze Age really really was the writing so once again just as a review because I actually I know I find this kind of confusing most our current understanding most of human prehistory and even pre human prehistory we spent were spent as hunter-gatherers using stone tools about until about eleven thousand years ago and then we became a little bit more settled we became farmers essentially using stone tools and then you fast forward another about five six thousand years and then we started to become farmers who started to write down the things that we knew and we started to use bronze tools