History and prehistory | The Origin of Humans and Human Societies | World History | Khan Academy

Aug 9, 2023

History and prehistory | The Origin of Humans and Human Societies | World History | Khan Academy

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How do we know what we know about prehistory, the time before the invention of writing? Sal explains.

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World History on Khan Academy: From prehistory to today, this course covers the human events that have shaped our planet.

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Content

0 -> - [Instructor] Anatomically modern human beings

2.16 -> have been on this planet for roughly 200,000 years.

7.04 -> And even though that's a small fraction

9.202 -> of the amount of time the Earth has been around,

11.344 -> which is over 4 billion years,

13.545 -> on a human scale it's an incredibly long amount of time.

16.843 -> Just to put it in perspective, if this is present time,

20.383 -> if you wanted to put, when was the Roman Empire?

23.183 -> Well, if we're talking about 2000 years ago,

25.542 -> it would show up on our timeline right about there.

29.96 -> If you wanted to talk about

31.09 -> when the pyramids were constructed,

33.098 -> it would be right about there.

35.133 -> You could hardly see the time difference

37.092 -> between now and several thousand years ago.

40.973 -> If you want to see how long we've had writing,

43.28 -> about 5000 years is our current best estimate.

46.591 -> Once again, it barely shows up on this timeline.

49.146 -> How long have we had agriculture?

50.922 -> Well, 10 to 15 thousand years.

52.442 -> Once again, it's a small fraction of this.

55.191 -> Another way to think about it,

56.65 -> think about all of our ancestors,

58.974 -> the various generations that have passed

61.32 -> since the first appearance

65.88 -> of anatomically modern human beings.

69.28 -> This is over 6 or 7 thousand generations into the past.

75 -> Think about all of the stories that must have happened.

78.483 -> A lot of simple things.

79.885 -> It might be a founding of a village,

83.856 -> a killing of an animal, a very simple courtship,

88.46 -> a tenderness between a mother and their child.

91.215 -> And think about the big things,

92.705 -> the wars, the battles, the natural disasters.

96.115 -> It's hard for us to imagine how much has occurred

98.301 -> even in the last hundred or two hundred or thousand years,

101.387 -> much less 200,000 years.

104.86 -> But we seek to understand regardless.

108.4 -> And that is what history is all about.

112.12 -> And as we'll see, history is in general

114.192 -> trying to understand the stories of our past.

116.99 -> And if we want to get a little bit more technical,

118.85 -> we can also think about prehistory, which is, technically,

123.177 -> the things that happened before we had writing.

126.68 -> Because writing is our main tool for history.

131.78 -> What I have right over here, this picture,

133.773 -> this is Egyptian hieroglyphs.

135.999 -> And Egyptian hieroglyphs are over 5000 years old.

140.24 -> I could write 5000 years before the present.

144.46 -> But even when you have writing, it's not enough

146.54 -> as we'll see not only in this video,

148.16 -> but in many videos as we study history and world history.

151.54 -> It's really a lot of science and a lot of detective work

154.937 -> to make sense of what has happened.

156.898 -> And that understanding will constantly evolve.

159.647 -> For example, we didn't know what these hieroglyphs said

162.7 -> until 1799 when we found the Rosetta Stone.

168.7 -> And what was useful about the Rosetta Stone

171.002 -> is that they had some text written in the hieroglyphs

175.584 -> and they had the same text then written in a Greek

178.237 -> that we were able to understand

179.978 -> and that started to help unlock what these hieroglyphs said.

183.9 -> But even once you have a sense of what they say

186.755 -> or even if you understand it quite well,

188.528 -> you still have to do a lot of detective work

190.683 -> and take everything with a grain of salt.

193.482 -> You can imagine

196.815 -> if there's a bunch of groups of people here

199.766 -> and we get the history from this group,

203.661 -> for some reason we were able to find what they wrote,

206.578 -> well it might not be completely unbiased.

208.848 -> They might have a negative view of this group or that group.

212.672 -> And so you have to take it all with a grain of salt.

214.553 -> At the extreme form, they might have eliminated

217.393 -> some of these groups and then only they were around

220.509 -> to say what actually happened.

222.982 -> You also have to be skeptical because you don't know

225.195 -> whether these stories are actual accounts

227.372 -> or whether someone just made it up to fit a worldview.

230.813 -> You also have to keep in mind that these stories,

232.623 -> whether they were transmitted written or orally,

235.867 -> they're oftentimes retransmitted

237.852 -> from generation to generation, and especially in the oral case.

241.489 -> But even in the written, you've gotta wonder

243.503 -> what's added over each generation.

246.33 -> You can imagine people embellishing,

247.759 -> making the story a little bit better.

249.384 -> Or taking out things of the story

251.798 -> that really doesn't fit in with their worldview.

256.138 -> So even when we have the writing,

258.801 -> and this is once again, some images of early writing.

261.878 -> This is the famous Sumerian cuneiform tablet here.

266.625 -> Even when we have it, obviously,

267.727 -> we have much much more writing

269.343 -> as we get to the more recent past,

271.409 -> we have to be very very very skeptical.

273.665 -> We know, today,

274.641 -> even if two observers observed something yesterday,

277.974 -> something that just happened, they might have

280.088 -> very very different perceptions of what happened.

282.439 -> So even though there's writing, we have to be skeptical.

285.158 -> But things get, in some ways, even more interesting

288.098 -> before we have writing, when we go into prehistory.

292.612 -> You might wonder how do we know anything about what happened

295.71 -> if there's no written accounts?

298.207 -> Well that's where the science

299.649 -> and we get even more detective work.

301.56 -> For example, this is a Neanderthal skull.

304.63 -> And the type of people, the sciences that will study this,

308.92 -> you'll hear terms like anthropologists.

313.38 -> Anthropologists or anthropology.

316.62 -> This is the study of present and past humans

319.811 -> and human society.

321.182 -> And then a subset of anthropology,

323.297 -> which is really delving into prehistory

326.808 -> and even history itself, is archaeology.

330.98 -> Archaeology which is the subset of anthropology

335.92 -> that focuses on the past study of humans and human society

340.251 -> and they're mainly going to do it through remains.

342.835 -> Now there's other fields, you might associate,

345.781 -> the field of paleontologist.

350.982 -> Paleontologist.

359.357 -> Paleontology.

361.548 -> You might associate this with things like dinosaur bones,

365.751 -> but their techniques are also useful for old human remains

370.952 -> or even pre-human remains.

372.946 -> And so it might inform archaeology and anthropology.

376.67 -> So for example, an archaeologist

378.364 -> might unearth this Neanderthal skull.

380.626 -> They will use some science in order to figure out:

383.051 -> When did this skull enter into the ground?

386.59 -> They might use a technique like radiocarbon dating.

390.486 -> Radiocarbon dating,

394.76 -> which could be used for things

396.214 -> up to around 50,000 years old,

399.376 -> so around that time span on our timeline.

403.2 -> And it's based on this idea

404.18 -> that you have this atmospheric carbon-14

408.02 -> that actually comes from nitrogen-14

411.824 -> that gets between interactions with the solar wind

415.662 -> and these cosmic particles

416.942 -> becomes this radioactive carbon-14.

419.61 -> And the carbon-14 which can become part of carbon dioxide

422.44 -> incorporate into plants through photosynthesis

424.609 -> which then get eaten into animals.

426.342 -> So while something is living,

427.983 -> they'll have a certain amount of carbon-14 in their tissue.

432.089 -> But then once they die,

433.58 -> they're now no longer adding more carbon-14.

436.32 -> And the carbon-14 decays into the more stable carbon-12.

441.08 -> And so based on the ratio

442.6 -> between the carbon-14 to the carbon-12,

445.18 -> and it takes roughly 5,000 years, 5,730 years to be exact,

451.06 -> for roughly half of the carbon-14 to decay into carbon-12.

454.241 -> So based on this ratio,

455.595 -> and I go into much more detail in other videos,

457.713 -> you can figure out how old these things are

460.327 -> and you get reasonably precise,

462.054 -> within a couple of a hundred, hundreds of years.

465.611 -> If you want to go further into the past,

468.085 -> there's things like potassium-argon dating,

473.2 -> which is once again taking a radioactive form of potassium

477.112 -> and using the idea that it decays into argon.

481.96 -> And that when a volcano releases the argon in that rock,

487.2 -> is able to go into the atmosphere, but then once it hardens,

490.081 -> you have the decay and so you can see

491.816 -> how long since that volcanic eruption are we looking at.

495.904 -> And so for example, you can dig,

497.265 -> you can do stratographic techniques right over here.

501.66 -> Stratigraphy, I have trouble saying these words.

505.278 -> That's looking at the various layers of the earth.

508.122 -> And you might use some dating techniques,

509.868 -> for example potassium-argon.

511.717 -> Say: "Okay, this is that, a certain amount of age,

513.985 -> "that is a certain amount of age,

516.141 -> "this was volcanic rock from a volcanic eruption."

519.938 -> And then you can look at the fossils.

521.554 -> You can say: "Okay, a fossil that I found here"

523.202 -> "is going to be newer than the stuff here"

525.605 -> "and it's gonna be older than the stuff here"

527.279 -> "and this might be the newest of all."

529.665 -> So you can look at relative dating

530.993 -> and if you're lucky enough to have some volcanic rock,

532.751 -> you could do some of this potassium-argon dating

535.79 -> and there's many many many other techniques.

538.744 -> And it isn't just about saying: "Oh, this skull

541.33 -> "was in this place in the world at this time."

544.418 -> You can start to infer other things.

546.388 -> You can look for fossils of the type of animals,

548.9 -> the type of plants near these burial sites.

551.379 -> You could see how dense these burial sites were,

553.441 -> what type of cultures were there.

555.049 -> You could start to make inferences.

556.779 -> You can try to infer how these people died.

559.695 -> You might have some trauma fractures here

562.033 -> and you might say: "Okay, that was a violent death."

563.689 -> You might look at their teeth to think about the type

565.612 -> of things they might have eaten or their general health.

568.869 -> You might look at the tools that are buried near them.

572.107 -> This right over here, these are Paleolithic arrow,

576.095 -> I guess, spearheads or tools right over here.

578.663 -> Paleolithic is defined by more of these harder edges.

581.688 -> You have Neolithic tools

583.27 -> which have more of these smoother edges.

585.239 -> Then Old Stone Age, New Stone Age right over here.

588.561 -> And by looking at all of that,

590.153 -> you have all of these scientists, you have these

592.822 -> anthropologists, archaeologists, paleontologists,

595.164 -> who are starting to piece together prehistory.

598.417 -> And sometimes these techniques are done together.

600.217 -> Sometimes we have writing and we have these technique

602.882 -> to try to get a more complete picture.

605.843 -> Now I want to end with just a note of caution.

609.332 -> Even though we have all of these techniques,

611.529 -> we're learning more everyday, our understanding

614.743 -> of all that has happened is very very incomplete.

618.687 -> And even more, it constantly gets challenged

621.332 -> the more we learn.

622.509 -> There are things that very serious people believed

625.022 -> 50 or 100 years ago that we have now proven to be false.

628.872 -> And things that we now take very seriously,

631.102 -> it's likely that in 50 or 100 years

632.879 -> people might prove some of that wrong.

635.239 -> So history, even though it's about the past,

637.33 -> it is constantly evolving.

639.035 -> We're constantly learning more

640.555 -> and we should have a very solid humility

643.346 -> about what we know and what we don't know.

Source: https://www.youtube.com/watch?v=ObGarwy5Jss