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澳大利亚土著如何用火改变了他们的环境. Sal Khan 创建




pharming as we now associate the word has been around for about seven to ten thousand years and when we think of farming we imagine a farmer planting seeds and later harvesting the crops or maybe having cattle that they can allow to graze and then using that cattle for either meat or milk or wool but there's actually a different type of farming that predates this this association with kind of I guess what we could call the traditional farm form of farming and it predates it by several tens of thousands of years and we believe that it started with it started with the original inhabitants of Australia and what they did is and this is why we call it farming and because if you think about farming in the most general sense it's really humans using technology to manipulate their environment so it becomes more suitable for humans so it becomes more suitable for things that humans might want to eat or get milk from or or or whatever and this type of farming is called firestick farming firestick farming and i think you can already imagine what it might involve it involves using fire which is really a form of technology or it can be a form of technology using fire to make the environment more suitable for for human activity and so what the original Australians did the indigenous australians or sometimes referred to as the aboriginal australians aboriginal aboriginal australians and if you're wondering where the word aboriginal comes from you might recognise some parts of it original you know what that means the original the first things the the the things that were there from the beginning and then you have AB which is Latin for from so this is literally from the beginning so you say Aboriginal Australians you're really kind of saying the Australians that were there from the beginning and so what they would do is is that we believe if you go back 50 or 60 or 60 thousand years before the first Aboriginal Australians settled Australia Australia had much more forests it still has for us this is a modern picture obviously of an Australian forest but what they did is that they set up controlled burns and what these controlled burns did is they they cleared away a lot of the forest they cleared away a lot of the brush that's at the bottom of you know that's over here and it made it much more suitable for grassland to develop and the reason why they liked grassland so let's make a little cycle here of what they did so they have controlled burns controlled controlled fires those controlled fryers helped promote grassland and then once you have grassland that made the environment more suitable for animals that that the the original human settlers could essentially live off of that they could hunt that they could potentially eat their meat and so for example things like things like things like kangaroos and these supported the human population he supported the human population which obviously would then do the controlled burns and you see here so we could have started off with something like this someone provides a controlled burn and and they were actually pretty scientific about how they did it that they wouldn't just go at the end of summer when everything was you know hot and and and ready to just blow up and they'd start a fire that they couldn't control they would often do these in seasons knowing that it had a certain level of moisture in the air as a certain it wasn't too hot and and to a large degree by doing these control burns not only did it provide an environment kind of do this firestick farming not only did it provide an environment that was suitable for things like kangaroos some type of things that humans could eat but it also prevented major fires and you still see forest rangers doing this type of thing and there's some there's there's some reason to believe that what the original Australians did on some level was more nuanced and more fine-tuned than even what what we do in a modern sense and controlled burns so these controlled fires also prevented prevented major uncontrollable fires prevented major fires because what happens is if you if you don't have these controlled fires then you have brush building up year after year after year you have stuff building up and then and then when the fires do occur they're not going to occur there or they're less likely with the uncontrolled fires are less likely to be started during the winter when the air is cool or when there might be some moisture they're more likely to occur in the driest season so you have all this stuff build up and then when the fire does happen it happens in the driest season and then when it happens with all of the stuff build up in the dry season it just becomes it just becomes uncontrollable one of the byproducts are actually there's several byproducts of this firestick farming we believe is a lot of the grassland in Australia now might have been more forested more forested before and even when the first European settlers came in the late and the late 1700s they were kind of surprised when they went into what is now Sydney Harbor and they said wow look at all the grassland here it almost looks like Park space and and then they would you know they would let their sheep graze there and they were surprised what because they had driven out the the original inhabitants and then they were surprised when forest just started to grow up in that grassland and it was because the original Australians were actually controlling that forest growth to make it more inhabitable for things like for things like kangaroos and then when the when the English settlers came they started to have you know their sheep graze in the in those grasslands and it also is responsible for for the disappearance we think of many major I guess for lack of a better word megafauna so it you know really large animals that that inhabited in Australia for really millions of years until humans showed up and this is one of them is just a neat - to look at them this is called drip to dawn optimum or another way to think of a the giant wombat and there's fossils of the giant wombat around 4050 thousand years ago but they disappeared with humans showing up and there's multiple ways that you could think about why they disappeared they might have and this was probably the case they might have been more dependent on the forest habitat on the forest habitat or this was a more favorable habitat for them than the grasslands maybe because they ate leaves that were high up or another thing is once the forest habitat goes away they were actually also easier to hunt down or either way you think about it they might have just been hunted by humans but we do see that with humans coming to the Australian continent you start to see the disappearance and this isn't the only one but there was several major species of megafauna of super large animals that disappeared at that time period