AP®︎/College US History
Darwinism and Social Darwinism are explored, debunking the misconception of 'more or less evolved' species. Natural selection's key ingredients are variation, heritability, and survival and reproduction. The video illustrates this with beetles adapting to their environment, emphasizing that evolution is not a linear path but a branching one.
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- They said we are all connected with a common ancestor, does that mean we are all part bacterium? Or were they talking like Adam and Eve?(4 votes)
- Descent from a common ancestor refers to a common ancestral species which two different species ultimately descended from. If you take any two currently known species on Earth, they are distantly related by some common ancestral species if you go back far enough.(13 votes)
- Wait, so how come let's say Americans look different then lets say Chinese? Like the eyes look different and skin tone is different, and if I'm right, body shape (like size) is different as well. So does evolution still make us different, or are we still the same?(6 votes)
- This is an excellent question (I've given it an upvote) and I'll attempt a response, but first we have to consider that the lesson is about SOCIAL Darwinism and you're asking about Biology. You'll probably get a better answer to it in one of the many excellent Biology classes here at Khan Academy.
That leads me to attempt the following. Differences in eye shape and skin tone between peoples of different regions (Asian, African, Caucasian) are as insignificant in human terms as differences within those groups (eye color, hair color, height, etc.). After all, when one needs a heart or kidney transplant, or even a blood transfusion, the parts imported don't come with "racial coding." We are human, and that's what's most important.
For the biological, I urge you to select one of the Biology Courses, find the specific lesson on evolutionary biology, and start reading there. Don't forget to read earlier learners' questions (probably someone else has already asked this very question) and the responses they have received. That's how we learn from each other.(5 votes)
- If I understand correctly, natural selection has a strong element of randomness. Please comment.(7 votes)
- Berkley University has a good article on the misconceptions about natural selection here:
- what comes first the chicken or the egg(4 votes)
- the chicken, because in the bible god created 2 of every animal. he did not create eggs in the bible the chickens that god created, created the eggs for people.(1 vote)
- if every thing comes from the same ancestor why are the beatles different colors?(1 vote)
- Each of them would have random genetic mutations that cause them to be slightly different, whether different behavior, or in this case, different color. These mutations arise because when DNA is copied, the process isn't perfect, and small mistakes will occur naturally. Mutations are what allows organisms to evolve via natural selection. This process of evolution, taking place over more than 3 billion years is what created the diversity in organisms today.(5 votes)
- Has anyone ever considered that God might have created the earth?(2 votes)
- at6:23, wouldn't it be eaten instead of et?(3 votes)
- in the "least to most" evolved line of humans where they put whites as most evolved and Africans, Asians, and eastern Europeans where put in least, where did Mexican Americans fit during that time period?(3 votes)
- Could one group in one part of the world evolve differently then another part. Is it possible like it was possible for different groups back around, " Lucy."(2 votes)
- Absolutely. There are people today with DNA from Homo neanderthalus as H. neanderthalus interbred with Homo sapiens. Evolution is the result of accidental mutations and interbreeding. You might like to take a look at the Big History Project content.(2 votes)
- [Voiceover] Hey, this is Kim from Khan Academy. I am the History Fellow here, and I am here with Emily. - [Voiceover] Hi, I'm the Biology Fellow. - [Voiceover] So, Emily and I are here talking about Darwinism. I'm interested in Darwinism, because in the late 19th century, usually called the Gilded Age, there is a very prominent interpretation of Darwinism that is called, Social Darwinism. Social Darwinism wasn't so much an actual form of biology, as it was, kind of a misinterpretation of how natural selection and the theory of evolution worked, that was used to justify or explain a lot of the social inequalities of this time period. The way people often thought about it was that white Anglo-Saxon people, so Europeans, Northern Europeans, were kind of the most evolved. This is our timeline of evolution, from least evolved to most evolved, and people like African Americans, or Asians, or Native Americans, or even Eastern Europeans, were less evolved. That they were on a scale of evolution where they hadn't come as far as Anglo-Saxons. So, Emily, you're a biologist, and I would love to get your take on how it is that natural selection actually works, and how this doesn't quite describe what was really going on. - [Voiceover] Yeah, definitely. So, maybe I can speak first to that specific graph that you've drawn on. I think that this is actually a common point of confusion when it comes to evolution, that there's not really such a thing, as more or less evolved in evolution. So-- - [Voiceover] Okay, so, this gradient really doesn't exist. - [Voiceover] No, I mean, there's sort of the, I think that people sometimes see the pictures of like, the ape standing up, and turning into a person, and they think, "Oh, this is sort of a linear path "from one thing to another." What you really get is different types of organisms evolving from a shared ancestor, and branching off. So-- - [Voiceover] All right so-- - [Voiceover] Nobody who's alive on Earth today has been evolving for more or less time, since their last common ancestor, than anybody else. - [Voiceover] So would you, I'm gonna draw what I think is how you're explaining this, and please correct me, as I go along. Say this is my common ancestor, and then would there possibly be branches like this? - [Voiceover] Yeah, that's a great way to draw it. Certainly, humans are all extremely closely related to each other, but we could even say this for us, versus a dog, a bacterium. Pretty much anything, all life on Earth, shares a common ancestor. That bacteria is just as evolved as you are, actually, in this sense of absolute time, since those two split apart. - [Voiceover] Right, so from the moment that life first appeared on Earth, there has been so much time, and all of us have been evolving from that point. Even whether you're a piece of bacteria, piece a good word? A bacterium? - [Voiceover] There you go! - [Voiceover] Excellent. - [Voiceover] Beautiful. (laughs) - [Voiceover] So bacterium. I took biology once, or you are Albert Einstein. You have been evolving for precisely the same amount of time. - [Voiceover] Yep. - [Voiceover] Awesome. Okay, wow, I'm really relieved to find that I could describe that as well as I could. (laughs) - [Voiceover] You did a great job. Beautiful. - [Voiceover] Okay, so you've done this, this distinction between evolving from a common ancestor. How is it that the actual theory of natural selection works? - [Voiceover] Yeah, that's a great question. So, natural selection, often people talk about it as sort of, having three key ingredients. To see how it works, let's imagine that we're just looking at a population of beetles. So picture you're beetles, to start with. What would we need to have, in order for these beetles, as a group, to evolve by natural selection? One thing that we would need is, we would need some variation among the beetles. - [Voiceover] Okay. - [Voiceover] So, if you have identical beetles, you're not going to have any that are better at surviving or reproducing, than any others, which is kind of a key ingredient, for what we're gonna talk about. - [Voiceover] Okay. So, I've got two different beetles here. They're slightly different from each other. - [Voiceover] Awesome. You've made them different colors, which is perfect. We have variation, and the next ingredient that we're going to need, is we're gonna need that variation to be heritable. We're gonna say that those beetles, one of them is green and one of them is blue, and that's because of something in their DNA. They have differences in their DNA, that create the variation in colors. - [Voiceover] Okay. Alright, so, when you say heritable, you mean that this is something that their descendants could inherit? - [Voiceover] Exactly. That is exactly it. So the final ingredient is that, the differences, these heritable differences, need to affect how good the beetles are at leaving offspring in the next generation. - [Voiceover] Alright, okay. - [Voiceover] For example, let's say, we would probably have more than two beetles, in our actual population -- - [Voiceover] Okay. - [Voiceover] But, let's say this population has just moved into a new area that is very blue colored. - [Voiceover] Okay. - [Voiceover] So blue rocks, blue flowers, whatever. There's also a bunch of birds in that environment that really like to eat beetles. - [Voiceover] Oh. - [Voiceover] I'm guessing, that if they have blue beetles and green beetles, that one of those is gonna show up a lot better against the blue environment, than the other. Probably a lot of our green beetles are gonna get picked off by birds, and they're not gonna be able to leave offspring, because gosh, they kinda got ate. (laughs) So, when you look at the next generation of beetles, if we know that the colors get passed on -- - [Voiceover] Mm-hmm. - [Voiceover] We're gonna probably see a bigger group of, a bigger proportion of that group, being made up of blue beetles, and less being made up of green. That is an example of natural selection in action, where you can see that organisms that survive and, specifically, reproduce better, in a certain environment, are going to increase in frequency in a population. You're gonna get more and more of these blue guys, less and less of the green guys. - [Voiceover] Is there a word you would use to describe this, sort of, this adaptation? Is that the natural selection part, as from variation, inheritable? Like, the natural selection is just like a good situation? - [Voiceover] Yeah, I mean, natural selection is really, just the differential survival and reproduction. As you mentioned a great word there, which is adaptation. - [Voiceover] Mm-hmm. - [Voiceover] Adaptation is the word that biologists often give to the process of a population getting better and better suited to its environment. You would say that the population was adapting to being in a blue space -- - [Voiceover] Mm-hmm. - [Voiceover] As it gradually started to have more and more blue beetles, across generations. - [Voiceover] What I find really interesting about this, is that it's entirely by chance, right? More or less, you've got a genetic mutation, and then that mutation happens to suit the environment that you're in, which allows you to thrive and your genes, and your adaptations to be passed on, over time. - [Voiceover] Yes! I mean, the variation would have occurred randomly to start with. Like you say, it would've been a mutation, it didn't happen 'cause the beetles went to a blue place, and said, "Gosh, I should be blue, that would be awesome." That was not what happened. It was already there and it just happened to be successful in that environment. If they'd gone to a green place, well, guess what? You would've gotten exactly the opposite effect. Suddenly, the green guys would've been more successful, more able to leave offspring, and you would've seen green be increasing or, "favored by natural selection."