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In Uncategorized on January 23, 2010 by bcnjake

I thought this article from the Times of London might interest a few people.  It’s a discussion of how wolves evolved into dogs and touches on a lot of the points in the Waters piece (especially artificial/natural selection).

Richard Dawkins: The Truth Dogs Reveal About Evolution

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7 Responses to “”

  1. Thanks for sharing the link! A fascinating discovery, written by a wonderful author.

    However, I suspect the analysis and the experiment of the Russian silver fox does not support the thesis that dogs were “self-domesticated” by the natural selection of shorter flight distances.

    First of all, while shorter flight distance is a characteristic of tameness, it is not the case the other way around. Judging from the way flight distance was introduced, it is a behavior that creatures would have only to other creatures that are considered as (or potentially as) predators. (Indeed it would be incredible if creatures would have flight distance issues with all living beings that are nearby but not of the type that would present a threat.) However, if a creature X initially regards another creature Y as a potential threat and decreases its flight distance as it gradually realizes that Y is not a threat (for example, both are herbivores), does this count as X “taming” Y? Or is it just getting along? Thus having shorter flight distance is not a sign of tameness.

    Let’s look at the Russian silver fox case. I assumed that the experiment was provided to show how artificial selection of shorter flight distance would cause tameness. Thus it is possible that this might have been the case for dogs. However, in the experiments, the experimenters, instead of merely selecting for “shorter flight distance”, in which they could just select the animals that did not run away when a human being loomed in a certain distance, they were actually selecting for domestication. They “offered their hand” and selected the cubs that “positively approached the handlers, wagging their tails and whining.” In this case, it is hard to tell whether it was the selection for shorter flight distance or the selection for human affiliation in a subordinate way (which is what we mean by domestication) that caused the change in behavior. What this experiment shows us is merely that selection for domestication gets us domestication. Wasn’t this the original hypothesis for the dog case?

    Thus, this article does not support its thesis, that self-domestication, or natural selection of shorter flight distance, was part of the cause of domestication of dogs. It seems more likely that the dog’s decreasing of flight distance either created a chance for domestication or was a consequence of domestication. It might also be the case that I misunderstood Dawkings’ point.

  2. I believe Dawkins’ main point is, as Darwin argued, that artificial selection and natural selection are so similar and linked that the finer points of the ‘end’ of the process of natural selection and the ‘beginning’ of the process of artificial selection in the creation of the domesticated dog is seamless.

    I think the difficulty you are having is being hung up on ‘tameness.’ ‘Tameness’ is merely a collection of behaviors and traits that humans select that we prefer in domesticated animals. They are somewhat arbitrary. Little or no flight response to humans is one of those qualities, for obvious reasons.

    Thus the intermediary wolves that had less of a flight response are only ‘more tame’ than their more wild siblings in that they possess more of a trait that we define as ‘tame.’ This first step may have even been necessary before humans could consider attempting to domesticate wolf-like dog things and breed them to more fully conform to what we see as ‘tame.’

    Thus, part of the evolution from wolf to domesticated dog was ‘natural’ selection. Though, it might be interesting to debate if an evolutionary changed precipitated by the appearance of large human waste dumps in the environment is a ‘natural’ or ‘artificial’ selection.

  3. Good point about the boundary between artificial and natural selection, Todd. It is important that there is no single selection event here and there may have been a long process of sorting wolf-dogs into dog-wolves based on what domestication means and what the plasticity of the species permitted across time. My other though is that Sewall Wright constructed his theory of evolution based upon his breeding 30,000 generations of guinea pigs as an employee if the USDA and developing the method of path analysis to describe inheritance. You may think your life sucks. Think 30,000 guinea pig litters… Luckily, Harvard hired Wright away and liberated him from guinea pig poop.

  4. I’d be curious to hear a case that human waste piles constitute artificial selection. My understanding of artificial selection is that it is selective breeding of animals for desired traits, which doesn’t seem to be happening in trash dumps. As I’ve read it, the process went something like this: people dump trash in living area -> people get sick and die -> someone hypothesizes a correlation -> trash is moved -> people stop dying as frequently/the disease dies out -> trash is kept outside the camp.

    I don’t see how it could be done (at least initially) without some human tribe/village/etc. putting the waste pile outside of camp for the explicit purpose of luring and taming wolves. Yes, moving trash outside of a camp is humans influencing the natural world, but not in a way that entails evolution through artificial selection. As an analogy, imagine the world goes up in nuclear holocaust destroys all human life. Clearly, this would be humans altering the natural environment and any animals that survive would (likely) evolve radically. But we wouldn’t be selecting for any of the traits that evolve, since we’d all be dead.

    I think that to argue that evolution spurred by human interaction with the environment necessarily entailing artificial selection requires arguing that humans are somehow outside of nature, but I don’t see a sound argument for that one.

    • The argument is indeed what constitutes nature and what is artificial. If humans do not stand outside of nature, then there seems to be nothing that is artificial. That is to say, there is nothing unnatural in the deliberate selective breeding of dogs by humans. All artificial selection would be natural selection.

      But, on the other hand, if human interaction with the natural world can create ‘artificial’ conditions, how is a human garbage dump natural? A human waste dump on the edge of a human settlement is not a naturally occurring phenomena. The appearance of this unnatural phenomena creates a new niche for survival and dog-like wolves move into this niche. Those with a reduced flight response do better. So, the argument would go, the unnatural condition lead to the selection of reduced flight response being more dominant in a population. This then would be an ‘artificial’ selection as it was created by a human created change in environment, that is not natural.

      The origin of this debate is precisely that strange place humans dwell in- in nature but not a part of nature. Why is anything a human does unnatural? Part of my suggestion is that ‘artificial’ selection can take place without the deliberate or conscious application of the intent to select. Natural selection has no will, intent, or desire, yet there is selection. So, why does ‘artificial’ selection require the application of conscious intent?

      Now, if we define ‘artificial’ as requiring intent, then we have a clear distinction between natural and artificial selection, but this could create other problems. There is an interesting example from Carl Sagan’s Cosmos of artificial selection.

      There is a legend of Samurai from antiquity (I can barely remember this part) escaping some dishonorable end by drowning in the sea, never to be seen again. The legend was that crabs with the face of a Samurai on their back was an incarnation of these warriors, and it was either bad luck or disrespect to kill such crabs, so they were tossed back by fishers. Initially there were few crabs with the face on the back, but now they are the dominant form, for obvious reasons- all the competition was eaten by people.

      I just looked that up. It is the Heikegani crabs. http://en.wikipedia.org/wiki/Heikegani
      Sagan used this as an example of ‘unintentional artificial selection’. So if ‘artificial selection’ can be ‘unintentional’ then the artificial condition of the human dump on the edge of town could be argued to be another example of unintentional artificial selection.

      If ‘artificial selection’ must be intentional, then both Sagan’s example and the unintended consequence of dog-like wolves moving into dumps would be occurrences of natural selection. This, of course, assumes that such selections processes are either ‘natural’ or ‘artificial’ but one could imagine definitional frameworks that had more precision and tried to deal with that gray area of where natural ends and artificial begins.

      Perhaps that gray area is somewhere in starburst fruit chews. Those things have both artificial and natural flavors in their composition, if memory serves.

  5. I do not agree that artificial selection is merely the interaction of living beings with men. There is nothing about men that stands out of nature such that the co-evolution between dogs & humans are any different from the co-evolution of ants and aphids. The way we usually use “artificial selection” indeed is the “intentional” selection of a conscious being toward other living beings. That is why the metaphor of nature as “selecting” has always misled the understanding of natural selection, since there is no intentional mother nature but only blind processes.

    The example Todd provided to argue against this point begs the question. The crabs were not “intentionally” selected by the Samurai to create Samurai-faced crabs. They were “unintentionally” selected by the interaction of the cultural beliefs of the Samurai and the crabs. The categorization of this as “artificial selection” already presumes artificial selection as merely human-involving co-evolution.

    The point in my original comment was that Dawkin’s article only shows that a lot of features that enabled the domestication of dogs is the product of unintentional natural selection. But who wouldn’t agree with that? There always exists some traits that enable some living beings to be domesticated easier than others, for example, that the creatures can live in conditions that we live in (polar bears are definitely not going to be easily domesticated and kept in a tropical ranch), can adapt to the versatile environments that we are adapted to, are easier to feed, etc. I take the force of Dawkin’s article to argue for a stronger point: that the very process of domestication was unintentionally selected for instead of intentionally selected by man.

    The goal of the Russian silver fox experiment is to show that the type of tameness we see in dogs can be selected for merely by the selection for shorter flight distance. By analogy, the dogs were domesticated because of the selection for shorter flight distance, not because men went out there and tamed the beast. However, as I already pointed out, the experiment fails to argue for this point as the experimenters were unintentionally selecting for subordinate friendliness with humans instead of selecting for shorter flight distance.

  6. I taught a course for a few years on agriculture from neolithic to modern eras. WE spent a great deal of time on domestication of plants and animals. The previous posts take a slightly different view from my experience (great!), but let me note a few things. There are only 14 animal species that have been domesticated (silver wolves notwithstanding). This has required significant human intervention beyond normal ecological interactions (commensalism, predation, symbiosis, etc), so I would regard this as non-natural selection. I will accept challenges on this. The evidence on plants is more interesting. The foundational species for wheat, maize, and most other domesticated (selected!) species released seeds throughout the growing season so as to optimize reproductive success and the seed pods were often singular and arrayed differently in the wild species. Humans selected for short reproductive seasons (so nomadic humans knew when to arrive for maximal harvest) and larger, more closed seed pods (easier harvest, protection from competitor species). We caused einkorn and emmer to evolve into wheat. We caused teocinte to evolve into maize. Lynn might ask is this is sufficiently different from other selection processes to warrant calling it artificial, as opposed to natural. I do not have an easy answer, but at the level of mechanisms in the selection among variations, I cannot find homologous behaviors elsewhere.

    What’s really cool is thinking of this as co-evolution. Wheat and maize and rice, when domesticated, changed humans. A DNA scan will tell if you are a corn-, wheat-, or rice-consumer.

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