# Evolution versus selective breeding **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 13, 2021, 2:24am UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266 "2021-11-13T02:24:22Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [November 13, 2021, 5:18pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/41 "2021-11-13T17:18:03Z")
> [@Riemann](#): > > Artificial selection can change some aspects of phenotype very quickly - turning a wolf into a Chihuahua in a few generations. But then it hits a brick wall. Because it was not based on schemata that were widespread in the population before the mutation was artificially selected. The OP addresses the difference between natural and artificial selection. Obviously the machine being modified is the same in both cases. But, the result is different. Evolution can only occur in populations not in a few individuals. Artificially introduced variations will quickly be diffused. Is there an example of stable artificial selection? ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [November 13, 2021, 5:19pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/42 "2021-11-13T17:19:35Z")
> [@Crane](#): > > schemata What does this mean? The reason artificial selection can make rapid changes and then hits a brick wall is beause it exhausts the preexisting genetic variation that was available in the starting population at the relevant loci. If there’s no longer any genetic variation in the subject population, the strength of selection is irrelevant - there’s nothing for selection to act on until new mutations arise. > [@Crane](#): > > Is there an example of stable artificial selection? What do you mean by “stable”? ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 13, 2021, 5:29pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/43 "2021-11-13T17:29:26Z")
> [@Crane](#): > > Creating speciation by isolating two populations is Lamarkism. > **[Allopatric speciation](https://en.wikipedia.org/wiki/Allopatric_speciation)** > > Allopatric speciation (from Ancient Greek ἄλλος (állos) 'other', and πατρίς (patrís) 'fatherland') – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model: 86  – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. > Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodi... ---
**Author:** ![Tfletch1](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tfletch1/32/5340_2.png) [@Tfletch1](https://boards.straightdope.com/u/Tfletch1)\ **Post date:** [November 13, 2021, 5:31pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/44 "2021-11-13T17:31:01Z")
> [@Crane](#): > > Dogs have not evolved. ‘Breeds’ just represent variants in the worldwide dog population. There has been no speciation, so were all dogs released and allowed to breed naturally, the population morphology would revert to some common mutt whose characteristics are suited to the current environment. As @Riemann has stated, this is not a correct usage of the scientific definition of evolution. @The_Other_Waldo_Pepper posted the definition, “the change in the inherited traits of a population of organisms through successive generations”. Evolution can occur within a species without the formation of a new species. Some call that microevolution. In response to the OP, he is confusing a mechanism for evolution (selective breeding) with evolution itself. Mechanisms for evolution include natural selection, artificial selection, genetic drift (no selective pressure, just an isolated population where random mutations get passed along), or gene flow (migration of traits into or out of a population). There may be more mechanisms than that. ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [November 13, 2021, 5:45pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/45 "2021-11-13T17:45:08Z")
> [@Tfletch1](#): > > Some call that microevolution. Of course what you say is correct. However, it is not without controversy. I proposed that the path from Wolf to Pekinese does not represent evolution because the phenotype is not stable. By stable I mean that it cannot maintain itself without continued human intervention. So the scope of human intervention was more than just selection. Hence the difference between natural selection and artificial selection. Now, I foresee a counter argument that natural selection is driven and supported by the natural environment. And in artificial selection the human becomes the environment for both selection and support. Which wins the argument by definition. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 13, 2021, 5:51pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/46 "2021-11-13T17:51:50Z")
> [@Crane](#): > > Were your scenario to take place, there would be a progression toward the mean in both populations eventually resulting a merger. The “mean” for a Saint Bernard is a Saint Bernard. The “mean” for a Chihuahua is a Chihuahua. As long as like only breeds with like, each is selecting from only a limited subset of all the alleles available for dogs as a whole. There would only be “progression towards the mean” of “dog” if there were intermediate sized-breeds that could allow gene exchange between Saint Bernards and Chihuahuas in the long term. An option that my hypothetical was explicitly designed to rule out. In my hypothetical of only Saint Bernards and Chihuahuas, the Saint Bernard would probably still be able to interbreed with wolves, but the Chihuahua probably would not interbreed or would do so very rarely because of [mechanical isolation](https://www.britannica.com/science/evolution-scientific-theory/Mechanical-isolation) due to extreme size difference. ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [November 13, 2021, 5:55pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/47 "2021-11-13T17:55:48Z")
> [@Darren\_Garrison](#): > > The “mean” for a Saint Bernard is a Saint Bernard. If that were true, good Darren, then it would be easy to breed championship St. Bernards. It is not, The standard is maintained only by rigorous selection and inbreeding. There is ample evidence that the mean is closer to the Pariah dog. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [November 13, 2021, 5:56pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/48 "2021-11-13T17:56:01Z")
> [@Crane](#): > > By stable I mean that it cannot maintain itself without continued human intervention. This may be true of ridiculous extremes such as the Chihuahua, which are obviously a strained result of human whimsy. But I believe the modern consensus (or at least a credible possibility) is that the _primary_ process by which wolves first became associated with humans was one of self-domestication. In other words, it wasn’t that Thag the caveman found some orphaned wolf pups and thought they looked cute. It was ancestral wolves initiating the process, moving into a novel niche of association with human populations. And the specific wolves within the population that were best suited to this new niche were those that possessed certain traits that humans find acceptable and desirable - in other words, the wolves may have primarily self-selected, rather than being subject to any conscious artificial selection by humans. > **[Self-domestication](https://en.wikipedia.org/wiki/Self-domestication#Dogs)** > > Self-domestication is a scientific hypothesis that suggests that, similar to domesticated animals, there has been a process of artificial selection among members of the human species conducted by humans themselves. In this way, during the process of hominization, a preference for individuals with collaborative and social behaviors would have been shown to optimize the benefit of the entire group: docility, language, and emotional intelligence would have been enhanced during this process of ar In... ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [November 13, 2021, 6:00pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/49 "2021-11-13T18:00:09Z")
> [@Riemann](#): > > It was ancestral wolves initiating the process Indeed true. Have you seen the movie Grizzly Man - the Fox domesticates itself. Also the Russian Fox experiment indicates that the self domesticating animals have a different appearance. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 13, 2021, 6:01pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/50 "2021-11-13T18:01:02Z")
> [@Crane](#): > > If that were true, good Darren, then it would be easy to breed championship St. Bernards. It is not, The standard is maintained only by rigorous selection and inbreeding. There is ample evidence that the mean is closer to the Pariah dog. Okay, if every Saint Bernard looks more or less like a Saint Bernard (even if some aren’t “champions”) and they only breed with other Saint Bernards, where do you think those “regression to the mean” alleles come from? The alleles have to be in the population before they can spread and become dominant in the population. ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [November 13, 2021, 6:07pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/51 "2021-11-13T18:07:42Z")
Oh, your hypothetical has only St Bernards and Chihuahuas. I doubt it would take them long to hybridize. A mature Chihuahua would readily mate with a juvenile or runt St. Bernard. Dogs have a very high degree of natural variation. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 13, 2021, 6:10pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/52 "2021-11-13T18:10:07Z")
> [@mbh](#): > > Evolution in wild animals produces traits that are beneficial to the animals. > > Selective breeding in domesticated animals produces traits that are beneficial to humans. A few thousand years ago human decided that since the meat and milk of _Bos primigenius_ were tasty, they would try to pin some up for easy access. Today there are billions of _Bos primigenius_ descendants spread around the world. If humans had not thought the were tasty, then the species would be extinct. Being beneficial to humans has been highly beneficial to _Bos primigenius_ (and all of our other domesticated species with billions of individuals). ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 13, 2021, 6:14pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/53 "2021-11-13T18:14:56Z")
> [@Crane](#): > > Oh, your hypothetical has only St Bernards and Chihuahuas. I doubt it would take them long to hybridize. A mature Chihuahua would readily mate with a juvenile or runt St. Bernard. Okay, how about only these two? > **[Classics: Tallest dog meets shortest dog](https://www.guinnessworldrecords.com/news/2015/9/classics-tallest-dog-meets-shortest-dog-398403)** > > This week, we take a trip to the California State Capitol Museum in Sacramento, USA where two very important record holders were introduced in 2007. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 13, 2021, 7:49pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/54 "2021-11-13T19:49:27Z")
> [@mbh](#): > > Evolution in wild animals produces traits that are beneficial to the animals. > > Selective breeding in domesticated animals produces traits that are beneficial to humans. Where beneficial means reproductive success. Is the tail of a peacock really beneficial to him? The reproductive success of the praying mantis is not too helpful to the male. In selective breeding reproductive success is tied to what the breeder wants, as opposed to being simply success in breeding. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 13, 2021, 7:56pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/55 "2021-11-13T19:56:06Z")
> [@Crane](#): > > I proposed that the path from Wolf to Pekinese does not represent evolution because the phenotype is not stable. By stable I mean that it cannot maintain itself without continued human intervention. So the scope of human intervention was more than just selection. Hence the difference between natural selection and artificial selection. Not all natural evolution (as opposed to artificial or human driven evolution like selective breeding) is stable either. Evolution does local optimization, so unstable situations can easily occur leading to extinction. Why dogs require us (which has been a successful strategy for them) so do the various mites and bacteria that live inside us and on us. We might not have selected them, but if we go, they go. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 13, 2021, 8:09pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/56 "2021-11-13T20:09:41Z")
> [@Andy\_L](#): > > Humans have practiced accidental selective breeding > > [The Accidental Grain - How Rye Evolved Its Way Into Our Diet — In Defense of Plants](https://www.indefenseofplants.com/blog/2016/2/2/the-accidental-grain-how-rye-evolved-its-way-into-our-diet) > > This indicates that any border between “natural” evolution and “artificial” selection is pretty blurry. There’s also the famous example of the “samurai crabs”: [Heikegani - Wikipedia](https://en.wikipedia.org/wiki/Heikegani) ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [November 13, 2021, 8:30pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/57 "2021-11-13T20:30:12Z")
> [@Voyager](#): > > Is the tail of a peacock really beneficial to him? Yes, it attracts mates and intimidates predators. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [November 13, 2021, 8:42pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/58 "2021-11-13T20:42:31Z")
I thought that one was a little dubious, but I had heard of it (Sagan, of course) ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [November 13, 2021, 8:44pm UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/59 "2021-11-13T20:44:00Z")
Another wrinkle - some non-human creatures do things that would be considered selective breeding if people did them - like ants farming aphids. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 14, 2021, 1:39am UTC](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266/60 "2021-11-14T01:39:55Z")
> [@Voyager](#): > > Not all natural evolution (as opposed to artificial or human driven evolution like selective breeding) is stable either. All genes are at risk for mutation. In genes for traits that matter, damaging mutations get selected against. But if the trait no longer matters, broken genes are no longer weeded out by natural selection. Therefore all traits are stable only as long as they are useful. Think of loss of vision and pigmentation in cave animals, and loss of Vitamin C production in several animal groups. [Previous page](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266.md?page=2) [Next page](https://boards.straightdope.com/t/evolution-versus-selective-breeding/954266.md?page=4)