Human evolution overview | Life on earth and in the universe | Cosmology & Astronomy | Khan Academy
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An overview of human evolution. Created by Sal Khan.
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lol! sometimes I feel a little silly. I read comments about how these videos are helping kids at school and here i am watching them for the entertainment and educational value. My fav are the history ones, something in khanacademy for everyone i think :)
someone could grab the tail when they're fighting, haha that made me laugh!
Decendents of Homo sapiens are Norris anderthals.
Chuck Norris approves this message.
"Thanks for clarifying that Chuck Norris is not a separate species from the rest of us"
Yes it did. I saw a science program on BBC where they said that the reason why erectus could grow bigger brains was a mutation that made the jaw muscles weaker and smaller so that they didn't need the tough and thick supports for the muscles on top of the scull! That's amazing, just a random mutation ultimately leading to this science debate today! If it hadn't happened maybe humans would still just be grunting and shouting, hehe:)
i love how u notice your mistakes as soon as they are delivered....they always make me crack up.
Khan is a genius!!! Is there anything he doesn't know??
I think that we should stop using the word "belief" for scientific theory. And the word "theory" as well, it's too confusing for theists.
Believe - have evidence to support
Theory - can build an assumption on available evidence
No, a theory is indeed a proven fact supported by lots of evidence which evolution is supported by.
Yep, see where you're coming from. Damn, it gets complicated quick huh??
But theories can be refuted by strong enough evidence to the contrary, just because that's how facts work...beliefs, however, require fingers in the ears and a loud incantation of the words "lalalala" in the face of evidence to the contrary.
@@spidaminida Yes, theories can be disproven since science has the concept of falsification which only makes theories even more valid.
@@spidaminida Being edgy again?
@@Elmo914 I think you need to look up "edgy" because this was not that.
I am just curious, we all know that we have something call soul, thus we do think, create, and utilize things. By the same token if the great apes were our ancestors, why don't they have souls? Or did something happen during the "great" evolution process?
Your second clause is incorrect. Also the existence of souls is highly unlikely.
So Chuck Norris wasn't responsible for killing off the dinosaurs? Well, I learn something new everyday! Thanks mate!
@Redexn It's called the Theory of Gravitation. A (scientific) theory is a set of concepts that explain and predict observed phenomena. In order for a theory (not just an idea, like in common usage) to become a full scientific theory a lot of evidence is required. Scientists have different weird usages for the words theory and law for some strange reason.
@tommy605 You raise two very good points. 1) We know a LOT more today than Darwin did. The case is much more compelling now than then. 2) While the fossils alone are compelling, if they did not exist, the case for evolution would still be overwhelming.
What is a soul? How do you know it exists? If it exists, how do you know that it exists in humans? How do you know that it doesn't exist in apes?
@Nomoreidsleft Keep in mind there is evidence linking us.
Not talking about fossils, But talking about DNA,
Not talking about "Ow they look a like", But talking about Genetic markers,
Its called a marker because its passed on throughout generations, and each genetic marker is unique to the strain, so very easy to track, if you know where to look for.
Just like a paint gun, it help identify what 2 species shared a common ancestor and combining all the data to create a timeline/map of ancestry.
Personally I embrace anyone who wants to admit they disagree with evolution. If anyone wants to label themselves stupid it saves me the hassle of finding it out.
@th86stone No, it just so happens that words have different meanings depending on the context. When I say "Do you hear that sound?"; it's not the same sound as "I am safe and sound". Get it? Ahhhh....
@PedroGynVibes Oh, yes! The "good stuff" and wise source is that one that today says that drink coffee is good and healthy and tomorrow is bad and dangerous.
@ghostbuddy well, you know what I mean. We still have much more to learn about our world, so basically, we cant stick with what we have SO FAR. Just my point about evolution :D
@generationalist You said: "YOU accept it as a natural product of reality based on the evidence YOU have come to understand, to date." My understanding of the word "belief" based on the definitions I have read leads me to think that there is nothing wrong with replacing "accept" with "believe" in your sentence.
Believe: 1. Accept (something) as true; 2. Accept the statement of (someone) as true. (Source: Merriam-Webster Dictionary).
@iorixs There are people who actually study those old bones and recognize patterns that no other bones have and compare that to our own bones and then make the conclusions.
Believe it or not, there are people who observe nature and study it before going out and saying things. They are called scientists. And they should inspire us all to act like them - only talking about stuff we know about.
@biozamadotcom It's not a cliche, bioz, it's an important principle we learn in statistics. I agree that we should use science as a guide for this and not political, religious, or other prejudice. It's still unrelated to biological evolution. We should try to stay on topic.
Those who argue against evolution need to remember the epic time scale. Do you really think that humanity will still look exactly as it does now 10,000 generations from now?
Not your children, or your children's children...but TEN THOUSAND generations!
@TheFallibleFiend Your right. I did not leave the other part out because I was trying to mislead but because I agree with him. The workings of a single cell is so complicated I am astonished and amazed at it. I do not know of any complicated systems which overcome the second law of thermodynamics and build themselves up by accident? I am not saying it has to be magic. Your obviously well versed in the ideas are there any problems with evolutionary theory in explaining life?
Webster's Theory:
1: the analysis of a set of facts in their relation to one another
2: abstract thought : SPECULATION
Yes creationist ideas are downright goofy. What is interesting is that although Theory of evolution helps with understanding life it does not account for origin of life, the simplest cell far too complex to happen by accident. Nobel prize winner Francis Crick a staunch evolutionist quote " An honest man with all the knowledge available to us now could only state that in some sense the origin of life appears at the moment to be almost a miracle, so many are the conditions needed to get it going"
I love his pictures for modern man. Will Smith, the queen, and body builders. Well done sir... Well done :P
@iorixs I recall Dawkins referring to a specific experiment to serve as an example of evolution 'before our very eyes', taking place in a short timeframe where it could be observed within years. Not that we need it to draw conclusions, as put forward by others already.
"Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions" Nature 459, 239-242 (14 May 2009)
Huge advance is abiogenesis. Still have a long way to go to figure it all out, but this qualifies as a corner piece to the puzzle.
I love the idea of apes grabbing each others' tails in fights.
Humans have developed a new mode of evolution. Ideas and concepts are selected for and against over time, depending on how good the idea/concept is. In this way, we eventually selected the idea of changing our environment to suit us, which means that we are automatically the "fittest", because "fitness to an environment" depends on the environment. Since this shift in evolution, genetics have become slightly less important than socio-economic status.
And 65 million years into the future....we will have evolved into flying creatures capable of living in water where we believe we came from.
Nope.
@TheYipedo we still have much, much more to learn. During the times of the Enlightenment, there were the Heliocentric theory that was developed by Copernicus, which was derived from the earlier belief that the Earth was in the center of the earth. Just like that, facts and proofs of evolution will change over time.
@amercury7 complicated systems do not overcome the second law of thermodynamics. Evolutionary theory isn't intended to explain the origin of life. Nor does it need to - atomic theory doesn't explain the origin of atoms, germ theory doesn't explain the origin of germs. There are a lot of "holes" in evolution in the sense that we only have the big picture, but we now have a lot of details to work out.
ok last comment, let me correct/clarify something I said earlier. Humans evolved to take advantage of different food sources. Some plants also evolved to take advantage of animals by offering them tasty fruits so that they can eat it and spread the seeds around. Others evolved to keep animals from eating their fruits by making them poisonous/thorny. So yea, no coincidence, no spontaneous popping into existence just symbiosis and predator/prey relationships evolving over a long period of time.
@TheFallibleFiend Regarding abiogenesis (how life came about) I mentioned scientists have found an end piece - but there's still a lot of work on that. I doubt that anything we can do will ever find out how life actually came about. At best we can only figure out how it might have happened.
@Octamed I noticed that, but didn't think much of it. I can see, though, that those who make beginner videos should be very careful about this sort of metaphorical language, because students might take it literally - especially since it feeds into a common misrepresentation and misunderstanding of evolution.
Biologically the relation "is the same species" is not transitive. Given the genealogy A->B->C-> ... ->Z where "->" indicates "produces offspring" then every letter is the same species as both the preceding and successive letter.
@ghostbuddy natural selection is true, but im still doubtful about Evolution
@princejustin9 No... it is a law. We call it "The Law of Gravity" not "The Theory of Gravity".
It really is appalling how many people misunderstand Evolution, or deny it. Honestly, just because it is the "Theory Of Evolution" does not mean that it's not true. There is so much evidence for Evolution.
There's the "Theory of Relativity" but you don't see people deny that. But when Science is contradicting religion it's suddenly wrong.
It is understandable that someone who believes the Earth is thousands of years old instead of billions of years can have a problem understanding the huge diversity of life. But now we know it's more than 4.5 billion years old and that life begun 4 billion years ago, so it should be a bit easier to understand then than it was for the religious who believed the planet was "6 thousand years old". : )
@th86stone I agree that science should start using another word to avoid confusion for people who don't know the different meanings of *theory*:)
@Redexn no we dont, the "law of gravity" and the "theory of gravity" are distinct. gravity happens and its undisputed, but to explain WHY we have the "theory". the fact of gravity being "objects with mass attract one another", and the theory as to why is something like "massive objects curve space time".
@tommy605 The big bang is a great example. If you study how the ideas of it have changed over the last 50 years you can see that the prevailing idea of what the big bang was has changed with the prevailing ideas and assumptions of the scientists working on it and the mathematical assumptions they have made. Very little empirical evidence is available ( background radiation etc.). The idea has changed since its inception with who is looking at it and what there assumptions are, that is reality.
@armpitpuncher you said "If you don't believe something, that means that you think it's false, or it doesn't exist. I do think gravity exists, therefore I believe in it." I do NOT need to believe in gravity, I understand it. Gravity exists whether a person believes or not. Gravity is not a thought process it is a physical manifestation of reality. Belief is a thought process, a function of neuron interaction and subjective. Understanding is objective, the experience is shared. Do you understand?
Can you do a video about what the very first Homo Sapiens (once this species settled) did....i.e. around the world, What was the *earliest* human history / what was the earliest 'recorded date' of man's activities?
The "mammal ancestor" didn't have a stash or something, It just managed to survive because it was able to sustain low temperatures and adapt to chaotic conditions. Birds and mammals can maintain their body temperature whereas reptiles can't. And there is a debate going on if dinosaurs had that ability too.
@generationalist I do not think of the words belief and understanding to be synonymous at all and I never implied such a thing. I "understand" the theory of gravity and the evidence for it and therefore I "believe" that the theory of gravity is true.
@generationalist No, you are not reading my sentences properly. Sorry if I'm being unclear; it's quite late here. I am saying that the belief in something or acceptance of it, the way Sal is using it, comes after having attained the understanding we have reached. It comes after the scientific methodology.
If you accept or believe something to be true without the scientific understanding, that is when it becomes unscientific.
That quote of mine was paraphrased from the dictionary by the way.
@TheFallibleFiend I appreciate your comments and thoughtfulness. I am wondering if you dont think that the common idea of evolution to the man on the street is that it explains abiogenesis? or what he would call the origin of life on the planet?
thanks.
By standard epistemology, most people claim that you are justyfied to claim knowledge if you have justification to do so.
He does not have justification to claim that souls do not exists. But he can claim that people making claims about the existens of souls, are not justified in doing so.
But you are right, he is not justified in claiming to know that souls do not exists. (From most philosophers view.)
Just like no one can claim to know that santa exists. But he might see it as usefull.
I love how creationists come about saying that because its called a "Theory", it is not real in practice.
It just comes to show how poorly informed they are... but hey, the internet is your friend. Try to learn some new stuff through it instead of repeating the same fairy tale over and over again.
People act like animals, because we ARE animals. I am no more diminished by this fact than by the fact that I am composed of molecules, or the fact that my body contains more bacteria than human cells, or that my thoughts of affection for my children are electro-chemical reactions in my brain.
And it's actually a giant leap to go from "I don't know about something" to "therefore it must not be happening", kind of arrogant, particularly when you're talking to somebody who does know that it's happening. This reduces the level of respect they feel, and a lot of people's response to that lack of respect is to call the person they have no respect for names, which is why you get the namecalling. No excuse, but that's the reason.
@armpitpuncher that's right, but I agree, the wording didn't come out right. 'An ape like ancestor' is closer.
@davelantor No, you need to read up more on DNA decoding. You cannot compare markers of two different species. They don't have the same genes. Comparing genetic markers would not make sense. Comparing genetic markers is like looking at where all the punctuation marks are in a text. If the two texts are almost identical you can trace the lineage. The more differences in the text the harder it gets to compare. Eventually the complexity involved makes it impossible to tell.
I read in a book somewhere that humans are evolving at a much quicker rate than any other species. And I'd really like to know why.
@ProMajtas The same mechanisms that create change and variation within "kinds" (that term needs defining) allow one kind can become another. Observable evidence that this is so can be found in studies of phylogeny, the fossil record, genetics, developmental biology and the geographical distribution of species. This evidence requires some inference and interpretation, but it fits the theory of evolution perfectly, as no other theory (or theology) does.
@iorixs It is not presumption to say that the sun is billions of years old. It's a conclusion. We don't have to see "the thing" in science. It's sufficient to see "the effects of the thing." This is one of the ways that creationists commonly misunderstand science.
@marcelobetel I think that most scientists would agree that there are "holes" in evolutionary theory in the sense that there is a lot of hard work left to do. However, there are no "holes" in the sense that something has been found that could not possibly have evolved, or that evolution violates some fundamental law of science. The chance that evolution will be disproved is about the same as that the existence of electrons will be disproved.
@cuezed don't worry about the 'impatient' ones here :) Just learn it by yourself. Remember, even if it's not true you can still learn about it. Google 'evolution 101' and read through the berkley link. It's a nice overview.
Also if your opposition is religiously based, I've yet to see anyone show me why their religion doesn't work with evolution. In my experience it's 99.9% misunderstanding of what evolution actually is.
@scidek Sal has made some videos on Evolution and Natural Selection before. Also he always recommends not to skip subjects. So he's assuming that the people who are watching have a clear idea what Darwinism and Natural Selection is.
Also the videos are meant to show the subjects... it's not hard to find the evidence of what he's saying. He's right to not make the video any longer.
And Gates never said it should replace school. But for quickly reviewing subjects, you can't deny its usefulness.
lol gaddafi, the queen and chuck norris! very well played
There was a time when every brilliant mind in the world thought that the world was flat, then they found out they were wrong, they thought that the earth was the center of the universe, they were wrong, my point is don't be so close minded to believe that something is absolute fact just because someone told you it is. In my opinion it takes twice as much faith to believe in Evolution than it does to believe in God. With that being said, stop bashing Creationists because you could be wrong too.
I'm not religious but I do respect other faiths, but I think this is pretty accurate ( taking away any or ALL mystical aspects of history ) take on US as a species taking over the world and our primative and still animalistic urges.
can we stop debating whether evolution is real or not?
@biozamadotcom
The problem tends to be, when we create the conditions, that lead to their extinction. Humans also have a tendency to see beauty in nature, we don't need practical utility in their existence, to have a reason to protect them. Also, humans have a history of learning things that eventually apply to human engineering, or medicine, from other species. Sometimes species are a good source for medicinal compounds. if a species goes extinct before we discover it, we lose that.
@voutasaurus I'm glad you liked it. Aronra is a brilliant explainer. It kind of depends on the kind of classification we use: Linnaean or Cladistics. Linnaean mainly considered physical appearance, but cladistics looks at evolutionary relationships. Note that Linnaeus lived quite a while before Origin of Species. Anyway, you are right that we are not descended from modern monkeys.
Evolution is true, and denying it wont help, just like denying gravity wont make you float in mid air
@marcelobetel Why are you changing the subject? We're talking about The Theory of Evolution, not the origins of all things. I don't pretend to know the origin of all things, and Evolution is not meant to explain the origin of all things. It only explains the diversity of life.
Do you always do this? If you asked me where my car came from, and I showed you the factory where it was assembled, would you eventually lead the topic back to the origin of the universe?
@PedroGynVibes You've said: "The Bibile is just another superstition."
So, if you are a scientist and know so many things that can make you think like this, could you please prove what you say?
@RespectMyHate Slogans are not science. The majority of the population is ignorant of science and evolution. That's why we go to the scientists who actually understand the subject.
@DonOfTheInternet No, they don't think. It's just that the ones who happened to be the best at escaping got to multiply the most. Did he say that they were thinking? That's a mistake if he did.
@Octamed Also I asked HOW he created. It just says that he did. If I say 'I created this tv' you wouldn't assume I just made it appear out of nothing.
@biozamadotcom, I see your point. Some ideas that are selected seem to be bad ideas. But just because they exist does not mean they will continue to exist. It might become a relatively short lived idea.
Evolution is such a broad subject with (ironically for creationists) SO much evidence that it would require at absolute minimum a 10 video series to even explain the whole of it elementarily.
@iorixs trucks and wagons are not self-replicating organisms. It is not "presumption." It's conclusion from the vast amount of evidence - evidence that you ignore or unaware of.
@iorixs Please watch Sal's video on Natural selection, where he states over and over again that evolution if not based on a "long series of chance" as you put it. Oversimplifying points and beliefs is in itself a fallacy in any philosophic circle, so please refrain from doing so.
@alawrence89 : Evolutionary concepts are subtle, and careful wording is necessary to avoid confusion. For example, he keeps saying "and then this species evolved into that species." "Species" don't "evolve into other species," and it's important in talking about evolution to be very clear about such things.
Am I? Yeah, I have a PhD in molecular and cell biology.
@RespectMyHate Yes we have. J. Craig Venter, isn't that his name? The guy who lead the tem that created the first synthetic life-form? Check it out if you haven't. And the technology is still advancing, so it won't stop there. : )
@RespectMyHate nature is capable of elegance. Consider the cheetah and the gazelle, they are both evolving against each other by NATURAL SELECTION, that is the key. The faster and more agile cheetahs survive to catch more gazelle and have more offspring, while the faster and more agile gazelle escape more cheetah to survive and have more offspring. They are both evolving against each other, increasing their complexity and agility to incredible levels. Us humans are no exception to this trend.
There are other animals that use tools - and there are animals that communicate. There used to be other animals like humans - but they are extinct now.
@generationalist The problem word is faith. Not belief. There is nothing wrong with belief. Faith is only a subset of belief. Knowledge also is a subset of belief. You cannot know something without also believing it. Creationists will use absolutely any nonsense to convince their audience. And they will succeed because their audience wants vindication for their own beliefs(which are based on faith). You can't fault Sal for using a perfectly accurate term.
I see you don't understand the meaning of "scientific theory".
Since you haven't figured it out, I'll try and help. A "theory" is something that represents our understanding of FACTS (and you did seem keen on the importance of these) in a way that is accurate and consistent with observation. Fact and scientific theory are not separate entities.
Please try to educate yourself a little more before you impress your ideas upon people.
@scidek There are many ways to teach a subject. I think there are some relatively minor problems with the video. The path Sal has taken is that it's important first to establish exactly WHAT the theory is. After all, much of the argument is from creationists who often have misunderstands of what evolution means. Even many honest inquirers have had false knowledge implanted by popular media. The evidence for evolution is vast and would take many videos to present.
Carefully reasoned conclusions from meticulously collected data are utterly insignificant compared to the awesome power of "My Holy Book asserts otherwise."
@mothertory Evolution is much more than a personal opinion or a belief. Science recognizes the fallibility of humans which is why it works the way it does. Evolution is supported by and explains a vast amount of actual evidence - and is refuted by none.
I believe in science not magic.
Sal this video is fantastic.
@cuezed
Thats a non-sequitor, claiming we have a common ancestor with Monkies, and Moles, in no way diminishes what we are, and what we are capable of.
I like how Sal just emphasizes on the point on how the species are able to survive in 'today's world.
@iorixs You haven't done anything like homework on the subject. The actual scientists have done their homework and don't ignore the evidence as you do.
@twinzmom2 Okay so stop talking about how "this has gotten" then, I was trying to explain about how we see evolution in the world around us, what its signs are, and give you examples you can look up and find more out about than I can fit into these tiny boxes. You seem to not really be interested, but obviously I could be wrong, so before I start saying any more, I'll simply ask... are you interested, or would you rather not know?
@RespectMyHate IT is not a prediction of evolution that you should witness evolution in the span of a human life. There is speciation. Google : "Macroevolution: Examples and Evidence " "The Evolution List" site by Allen MacNeill . However, science does not require us to witness "the thing." We only have to observe 'evidence of the thing."
Another great vid.
Loving QEII, Mao and Gaddafi juxtaposed at the end.
This Khan Academy video will of course have the most comments ever
Hmm. Interesting hypothesis about mammalian species surviving well because they could dig underground. I don't even remember getting taught evolution in school, now that I think about it. Weird. I can only remember it being mentioned briefly in 4th grade.
@amercury7 Meanwhile science advances and have since discovered a corner piece:
Nature 459, 239-242 (14 May 2009)
"Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions"
granted, Science does not fully understand gravitation, but we know how to use it very clearly through the mathematical model.
@marcelobetel /sigh
The reason "Zillions of accidents happens" is because the universe is SO BIG, that something that gives the possibility of life is bound to happen somewhere in it. Although the probability of having the right circumstances for a planet like Earth to be like it is are extremely low, there are so many planets then at least one of them is bound to be like Earth. It's not 'accidents' its almost determinism in the fact that there are so many different planets in the universe.
@TheFallibleFiend A good explanation, bu still just another way to confuse readers of theories. I am not talking that YOU are confusing anybody. But a scientist should be clear like math when a theor or law is recognized.
Following your explanation the first question that pops-out is: So, what the laws of the evolution? Are they ok with all other laws of thermodynamics and so on?
So, a theory is a open to changes statement, and a law is not. That how sould be.
If you're not sure, call it theory.