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

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

– [Instructor] Anatomically
modern human beings have been on this planet
for roughly 200,000 years. And even though that’s a small fraction of the amount of time the
Earth has been around, which is over 4 billion years, on a human scale it’s an
incredibly long amount of time. Just to put it in perspective,
if this is present time, if you wanted to put,
when was the Roman Empire? Well, if we’re talking
about 2000 years ago, it would show up on our
timeline right about there. If you wanted to talk about when the pyramids were constructed, it would be right about there. You could hardly see the time difference between now and several
thousand years ago. If you want to see how
long we’ve had writing, about 5000 years is our
current best estimate. Once again, it barely
shows up on this timeline. How long have we had agriculture? Well, 10 to 15 thousand years. Once again, it’s a small fraction of this. 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. This is over 6 or 7 thousand
generations into the past. Think about all of the stories
that must have happened. A lot of simple things. 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. And think about the big things, the wars, the battles,
the natural disasters. It’s hard for us to imagine
how much has occurred even in the last hundred or
two hundred or thousand years, much less 200,000 years. But we seek to understand regardless. And that is what history is all about. And as we’ll see, history is in general trying to understand
the stories of our past. And if we want to get a
little bit more technical, we can also think about
prehistory, which is, technically, the things that happened
before we had writing. Because writing is our
main tool for history. What I have right over here, this picture, this is Egyptian hieroglyphs. And Egyptian hieroglyphs
are over 5000 years old. I could write 5000
years before the present. 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. It’s really a lot of science
and a lot of detective work to make sense of what has happened. And that understanding
will constantly evolve. For example, we didn’t know
what these hieroglyphs said until 1799 when we
found the Rosetta Stone. And what was useful
about the Rosetta Stone is that they had some text
written in the hieroglyphs 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. 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. 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. They might have a negative view
of this group or that group. And so you have to take it
all with a grain of salt. At the extreme form, they
might have eliminated some of these groups and
then only they were around to say what actually happened. 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. 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,
and especially in the oral case. But even in the written,
you’ve gotta wonder what’s added over each generation. You can imagine people embellishing, making the story a little bit better. Or taking out things of the story that really doesn’t fit
in with their worldview. So even when we have the writing, and this is once again, some
images of early writing. This is the famous Sumerian
cuneiform tablet here. Even when we have it, obviously, we have much much more writing as we get to the more recent past, we have to be very very very skeptical. We know, today, even if two observers
observed something yesterday, something that just
happened, they might have very very different
perceptions of what happened. So even though there’s writing,
we have to be skeptical. But things get, in some
ways, even more interesting before we have writing,
when we go into prehistory. You might wonder how do we know
anything about what happened if there’s no written accounts? Well that’s where the science and we get even more detective work. For example, this is a Neanderthal skull. And the type of people, the
sciences that will study this, you’ll hear terms like anthropologists. Anthropologists or anthropology. This is the study of
present and past humans and human society. And then a subset of anthropology, which is really delving into prehistory and even history itself, is archaeology. 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. Now there’s other fields,
you might associate, the field of paleontologist. Paleontologist. Paleontology. You might associate this with
things like dinosaur bones, but their techniques are also
useful for old human remains or even pre-human remains. And so it might inform
archaeology and anthropology. So for example, an archaeologist might unearth this Neanderthal skull. They will use some science
in order to figure out: When did this skull enter into the ground? They might use a technique
like radiocarbon dating. Radiocarbon dating, which could be used for things up to around 50,000 years old, so around that time span on our timeline. And it’s based on this idea that you have this atmospheric carbon-14 that actually comes from nitrogen-14 that gets between interactions
with the solar wind and these cosmic particles becomes this radioactive carbon-14. And the carbon-14 which can
become part of carbon dioxide incorporate into plants
through photosynthesis which then get eaten into animals. So while something is living, they’ll have a certain amount
of carbon-14 in their tissue. But then once they die, they’re now no longer
adding more carbon-14. And the carbon-14 decays into
the more stable carbon-12. And so based on the ratio between the carbon-14 to the carbon-12, 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. 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. 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. 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. And so for example, you can dig, you can do stratographic
techniques right over here. Stratigraphy, I have
trouble saying these words. That’s looking at the
various layers of the earth. And you might use some dating techniques, for example potassium-argon. 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.” And then you can look at the fossils. 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.” 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
many other techniques. And it isn’t just about
saying: “Oh, this skull “was in this place in
the world at this time.” You can start to infer other things. You can look for fossils
of the type of animals, the type of plants near
these burial sites. You could see how dense
these burial sites were, what type of cultures were there. You could start to make inferences. You can try to infer
how these people died. You might have some trauma fractures here and you might say: “Okay,
that was a violent death.” You might look at their
teeth to think about the type of things they might have
eaten or their general health. You might look at the tools
that are buried near them. This right over here, these
are Paleolithic arrow, I guess, spearheads or
tools right over here. Paleolithic is defined by
more of these harder edges. You have Neolithic tools which have more of these smoother edges. Then Old Stone Age, New
Stone Age right over here. 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 prehistory. And sometimes these
techniques are done together. Sometimes we have writing
and we have these technique to try to get a more complete picture. Now I want to end with
just a note of caution. Even though we have all
of these techniques, we’re learning more
everyday, our understanding of all that has happened
is very very incomplete. And even more, it
constantly gets challenged the more we learn. There are things that very
serious people believed 50 or 100 years ago that we
have now proven to be false. And things that we now
take very seriously, it’s likely that in 50 or 100 years people might prove some of that wrong. So history, even though
it’s about the past, it is constantly evolving. We’re constantly learning more and we should have a very solid humility about what we know and what we don’t know.

43 thoughts on “History and prehistory | The Origin of Humans and Human Societies | World History | Khan Academy

  1. As I get older I realize that so much that happens in a life no one will ever know. All the highs and lows, the loves and losses, the struggles to survive. There's so much even about my mother, who was remarkable, and whose life I witnessed so much of, yet I cannot convey satisfactorily to younger generations. But when I first saw online the cave paintings of Lascaux and Chauvet and Altamira, I recognized that people who lived tens of thousands of years ago, their encounters with life, their sense of wonder, are the same as mine. Suddenly I felt them present with me, and I was transported for a moment into their lives. And they, knowing in advance I would imagine this, greeted me.

  2. This video shows proof that something happened all of the sudden to humans; be it God, aliens, Satan, whatever. Us humans got really smart all of the sudden.

  3. Khan, do please subtitles russian.A then surely tell interesting, but takes a lot of translation time.Pleeeaase!)

  4. We don't even have history older than 1,656 years before the global flood. Egypt was founded by Noah's grandson Mitzraim and his mother Egyptus.

  5. Everything buried or placed into the sediment layers or soil existed after the global flood. Everything buried by the sediment layers existed before the global flood 4,400 – 5,000 years ago depending on how it's measured, considering that the patriarch Noah lived six hundred years before the global flood. (Most non-biblical ancient calendars are only 5,000 years old.)

  6. Khan, you truly have been on fire with this fantastic information. You're schooling all those other folks, who attempt to edify the people out there. Keep'em coming sir. Just great stuff you keep turning out.

  7. I've always wondered if we had highly advanced societies in the distant past scores of thousands of years prior to the earliest discovered writing. Stories like Atlantis really spark my interest.

  8. I can hardly even fathom 1,000 years let alone 200,000 years; and I don't wanna THINK about the ridiculous time spans that go back even further than that!

    Timescales longer than 1 million years leave me absolutely speechless!

  9. This guy said that the modern humans have been on this planet for 200.000 years, THAT'S FALSE, The oldest fossils of Homo Sapiens are 300.000 years and are found in Morocco

  10. So…anatomically identical and just as clever as we are now for 200,000 years, but no writing, etc., until over 95% of that time has passed by? Seems to go against common sense…

  11. to be honest its all assumption…and religion says adam was the first man on earth….we will never know the truth

  12. The Max Planck Institute discovered signs that the Homo Sapiens might in fact have been around for longer than just 200.000 years:


  13. so this is the oldest skull and archaeology examinations says it is 200 000years old, now how about if there is a skull more older than that, but unfortunately is reduced to dust due to its over age.

  14. Dude,you basically contradict yourself when you say 200,00 is still a LONG amount of time and then decide to explain how there is no time diffrence between now and several thousand years ago

  15. how do we know the starting ratio of carbon 14 to carbon 12 in an specimen from a particular time? wouldn't it depend on levels of atmospheric carbon at that time? always wondered

  16. Khan, I have literally read a lot of books on World History, Anthropology, and other related subjects, but man! You have left me speechless. Like, this is incredible. Keep the good work up! It's always good to hear you.. God bless you Sir!

  17. Wow, a video that looks at something that I have really been in awe of. All the modern human lives just before say the last 10 thousand years. Whole lives, whole huge events.

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