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Artificial selection and domestication

Artificial selection and domestication are processes where humans influence the evolution of species. Dogs, farm animals, and crops have all been shaped by these methods. Humans select which individuals reproduce based on desired traits, accelerating changes that would take much longer in natural selection. This has led to the diverse breeds of dogs and varieties of crops we see today. Created by Sal Khan.

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  • aqualine ultimate style avatar for user vipul
    Why exactly do dogs look so wildly different from their wolf ancestors? In some cases the similarity is striking, such as in the case of the husky, but when we look at breeds such as chihuahuas, its hard to even imagine that they're even related to other dogs, let alone that they're descendants of wolves. It just made me wonder as to whether there were other factors that resulted in these breeds looking so different.
    (9 votes)
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    • aqualine ultimate style avatar for user Yaelle
      Hi ! I would say human selection was the main factor here ;) Just like the banana you eat today looks nothing like its wild ancestors (you can google for pictures of wild bananas, and yuk, you would definitely not eat it), humans have selected and grown the mutations they liked in other organisms, and even crossed them in order to obtain something "better". And we've been doing so even before we knew anything about genes and all !
      (20 votes)
  • stelly blue style avatar for user Ichinea Iceflake
    how do we have German shepherds?
    (8 votes)
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    • duskpin ultimate style avatar for user RiverclanWarrior
      A long time ago, people started breeding wolves with certain traits, including those that are more protective or obedient. Eventually, they also started breeding dogs with not only the traits above, but also with large bodies, short fur, large ears, and so on and so forth. I guess someone eventually wanted brown fur, and so that happened, and add a few dozen years and we have German Shepherds!
      (13 votes)
  • starky ultimate style avatar for user ®oman
    How did they come to the conclusion that all dogs come from wolves? Is there actual evidence for that?
    (5 votes)
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  • male robot hal style avatar for user om nom nom
    How do you know that when you do artificial selection and it makes one trait better, for example, the trait which helps it mate better, it doesn't worsen a different trait, such as its eyesight? Is there a way to only, and emphasis only, change one trait to make it better?
    (6 votes)
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  • winston default style avatar for user JD lG
    Again these dog's are breeding inside their KIND no matter the amount of time you give it it will never change kind. God created Dogs according to their own k9 kind and Cats according to their own feiline kind.
    (2 votes)
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    • male robot hal style avatar for user Charles LaCour
      The way "kind" is interpreted in biblical terms would fall into the area of family or genus. This way of grouping is fine but this doesn't explain speciation within a kind.

      Staying with dogs they are a member of the Canidae family. Most of the Canidae family can successfully interbreed but there are the genus Cuon, Lupulella and Lycaon that can't in general breed with each other or other genus of Canidae like the other genus can.

      When you continue to have divergence the species of a family or genus the individual species become less and less like each other psychically and genetically. The the more genetic difference there is the less there is a chance of successful breeding. This is why there are no cat-dog hybrids, they are too genetically different to successfully mate, not because of the biblical idea of kinds.

      With genetics the ideas of adaption and divergence can explain how the various family, genus and species came about.

      Scientifically evolution has great explanatory powers that we can use to evaluate and explain things we experience. Saying "kinds" were created give little ability to explain new things.
      (10 votes)
  • blobby green style avatar for user vargafer000
    how are dog related to wolfs
    (4 votes)
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  • duskpin sapling style avatar for user Myth
    He states what rottweilers, border collies and terriers are good at but not what the chihuahua is good at. Does that mean chihuahua's are useless 🤔🤔🤔(⊙o⊙)
    (4 votes)
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  • duskpin ultimate style avatar for user SCeevee
    What does Sal mean by the mechanics could get quite difficult in
    (4 votes)
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  • aqualine ultimate style avatar for user Tas
    Rottweiler > Protection
    Terriers > Hunting rodents
    Border collies > Herding animals
    ...
    and then there's the chihuahua
    (4 votes)
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  • leafers tree style avatar for user Leafy
    I wonder if the humans from thousands of years ago
    knew that the wolves they bred would turn into the doggy's we have today
    (3 votes)
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Video transcript

- [Instructor] Most of us are familiar with dogs, often times known as man's best friend. And what's fascinating about them is that they are one species, even though different types of dogs, different breeds could look very, very different. And the fact that they're one species says that if you have a male and a female dog, any two, that in theory they could reproduce and produce viable offspring. Although in, for example, the case of this character and this character, the mechanics could get quite difficult. But an interesting question is, is where do dogs come from and why do we have these seemingly specialized breeds amongst dogs? You might have things like a Rottweiler that's better for protection, you might have things like terriers that have been specialized to maybe go after rodents. You have things like border collies that are good at herding other types of animals. The simple answer is, through artificial selection and domestication. Remember, in any population of a species there's variation in that species. And when we talked about natural selection, that's where the environment might select for certain of those variants. Certain of those variants might make it a little bit easier to survive or reproduce, and then those would predominate and that's how evolution happens. Artificial selection and domestication is where humans take matters into their own hands. And instead of waiting for nature to do things, they are the selection factor. They pick which of the species get to reproduce and which ones don't. And when you have that type of artificial selection, the change can happen much, much faster. Breeding is essentially artificial selection. So dogs like this, and all the dogs we know of had ancestors that looked like this, that looked like a wolf, that were a wolf. And what we theorize is that the early stages of some wolf eventually evolving into dogs might have been more traditional natural selection where tens of thousands of years ago our hunter gatherer ancestors as they hunted and gathering they might have left over food here or there, and some of the wolves that just happened to be the variants that were a little bit more comfortable getting close to humans might have benefited from being able to get some of that left over food, being able to get some of the remains that the human beings left behind. But then over time, human beings probably realized that hey, these wolves are useful to have around. Maybe they provide some form of protection, maybe over time they started breeding the wolves so the wolves that were especially friendly, the wolves that were especially good at a certain task, say protection, or going after some type of an animal or retrieving things, they allowed those to reproduce together and over time, over tens of thousands of years, we went from wolves to dogs. And even once we had dogs, the breeding got even more specialized. As I mentioned, things like border collies, this was many years, many generations of breeding where sheep herders might have selected dogs that were good at herding sheep. That terriers came from dogs that were good at going after rodents, things like rottweilers or dogs breeding the dogs that were especially good at providing protection or defense. And it isn't just dogs that are products of artificial selection and domestication. Pretty much any animal that you might see on say a farm would be the product of artificial selection and domestication. A wild pig looks like this, while the ones that you would see on a farm look like that. And once again, they would have selected for things like docility, things where they're less aggressive and they're easier to take care of. And artificial selection and domestication does not apply just to animals. Pretty much anything you might see in the produce section of your supermarket is the product of artificial selection and domestication. There might be wild variants of these different vegetables or these different fruits, but over roughly 10 or 15,000 years of human agriculture, every generation of crop they would have selected for the crops that are more robust, that tasted better, that were able to grow in different climates and by allowing those variants to reproduce, we eventually ended up with the domesticated crops we see today.