Classifying Selection as Natural, Artificial, Neutral or by Design

a guest post by Howard Hershey

**  This is repeated in its entirety from a post in the talk.origins newsgroup. It is in response to another poster, so parts may seem a bit strange without the defining context.  However, when I read this, I knew it was perfect.  It’s a way of saying what I’ve been trying to get across for months now.  How can you classify selection?

The full post from Howard is after the break.

Howard Hershey had previously asked for justification of a point in terms of Natural Selection (NS):

>> But you may continue to present the rest of this with appropriate
>> citation as to when, where, and who and how it fits into whatever
>> argument you have (if any) with the *modern* scientific understanding
>> of NS.

Causing a protagonist to ask what NS is:

> What would this be?

 The modern scientific understanding of NS? I have already described it. Let me repeat:

Howard reposts one of his previous explanations:

Rather than use examples unrelated to the biological meaning of the phrases “natural selection”, “artificial selection”, and “selective neutrality”, let’s use examples that clearly point out their meaning. I will give you an opportunity to make simple replies, but you will alsohave to justify those replies. I will justify what I say by always giving a “because” explanation of why I made the choice of terms I did.

 Remember that “natural selection” involves a comparison of two alternative features in an organism on some metric of “differential reproductive success”. I will use the metric of “differential survival until reproductive maturity” in my examples, but remember that there are other possible ways of measuring ‘reproductive success’.

We will be looking at an imaginary organism (but one that has features like many real ones), the Lake Monroe Oysters. The oysters have two alternative features: some are red and taste like shit, others are blue and taste like ambrosia. Once a year, the oysters, about a thousand strong, put out their little legs and walk to a small pond owned by Gene Poole, where they dump in all their gametes (sperm and eggs) and then die without ever going back to Lake Monroe. But, 10 days later, all the little oyster babies (about 10,000 strong) walk from Gene Poole Pond back to Lake Monroe, where they either grow up over the course of the next year or die. The survivors then repeat the process to make the next generation. And so on.

Example 1: The adults that go to Gene Poole Pond are 30% red/shit and 70% blue/ambrosia. They empty their gametes into the Gene Poole Pond and, because fusion to produce zygotes is a random process according to Mendelian genetics and according to the rules of Hardy-Weinberg, we get just about 30% red and 70% blue progeny in the pond that will travel back to Lake Monroe. Quite a number of these progeny (about 90%) will die over the course of the year (see Malthus for an explanation). But, when we look at the progeny that survive their year in Lake Monroe and go back to the Gene Poole Pond for the next oyster orgy, we observe that 30% are red and 70% are blue. What this means is that there has been no “differential survival until reproductive maturity” with respect to the two alternative features (phenotypes) we are following: red or blue. That is, all the death that has occurred was due either to chance alone or to features unlinked to the color/taste of the oysters. The key feature to look at is the % of red versus blue in the parent generation at birth (actually, at zygote fusion) and in the adult breeders.

 Now, of course, the actual percentages will probably not be exactly 30/70 for the same reason you would not expect to get exactly 50 heads: 50 tails every time you flipped an honest coin 100 times. But there are statistical ways to estimate whether the observed result is significantly different from such a random expectation. Observing a 31% to 69% ratio would not be a surprising result if the numbers are small enough in the population or in a random sample from the population. In this case, we would observe 310 red to 690 blue in the adult breeders. A deviation from expectation this large or smaller than the expected 300 and 700 would happen by chance about half the time, so I would consider this to be merely a chance deviation and not a significant deviation. [I am using a simple chi-square test and regard any deviation that could occur by chance 95% of the time to be non-significant.]

A second minor point, but an evolutionarily important one, is that, as many a gambler has found out, “chance has no memory”. If the new % entering the Gene Poole Pond is 31%/69%, the expectation of chance is that that (rather than 30/70) would be the expected %s entering Lake Monroe and exiting it the next year. This is the reason why selective neutrality leads to neutral drift and eventual fixation of one or the other phenotypes.

A third minor point. I am ignoring the diploid genetics of this case, so I am not examining specific genotypes. If I did, I might find that this is an example of “stabilizing selection” like that seen in sickle cell anemia. That would only be observable over a number of generations (by deviation from the expectations of random drift) or by examining the ratios of homozygotes and heterozygotes in the genes.

This is an example of the absence of “significant differential selection”. Or, if you prefer, an example where neither color had any differential effect on survival. In biology, this pure chance process is NOT called “natural selection” precisely because there is no differential selection related to the features. This example is (tentatively) called “selective neutrality” and leads to “neutral drift”. Again, this is NOT considered “natural selection”. However, the random walk that occurs by “neutral drift” does lead to evolution (genetic change) over time to the extent that these features are genetic. [And this would also lead to the discovery of “stabilizing selection” if that were the reason for the apparent absence of change.]

To summarize: In the absence of evidence for selection, there is no “natural selection”; there is “selective neutrality” leading to “neutral drift”. IOW, pure chance and only chance is NOT “natural selection”. It is “selective neutrality” and only selective neutrality that represents pure chance. There is no differential selection at all in the case of selective neutrality, unless it was done by a designer who was trying and succeeding in mimicking a completely random process (which is very difficult for humans to do without using a random number generator of some kind), there is no way to call such a result a product of “design”. So “selective neutrality” is almost always a “pattern” and specifically is always a “random pattern” wrt the measured metric of “differential reproductive success between the two alternative features”. The only way such a result can ever be a “design” is when a “designer” successfully mimics a random, pure chance result.

The only way to know that is by knowledge of the existence and intent of the “designer”. It would be impossible to tell by examination of the “pattern” alone. And, initially, it is not possible (if the genetics are unknown) to distinguish between “stabilizing selection” due to heterozygote vigor and “selective neutrality”. The difference between them would only become obvious as the pattern deviates over many generations from the probability expectations of neutral drift.

Now, it is your turn. Does the above random non-selective described process that biologists call “selective neutrality” produce “pattern” or “design”. Explain why you think so, if your thinking differs from mine.

Example 2: The adults that go to Gene Poole Pond are 30% red/shit and 70% blue/ambrosia and produce just about 30% red and 70% blue progeny in the pond that will travel back to Lake Monroe. Quite a number of these progeny will die over the course of the year (see Malthus for an explanation). But, when we look at the progeny that survive their year in Lake Monroe and go back to the Gene Poole Pond for the next oyster orgy, we observe that now 80% are red and 20% are blue.

 Humans had been forbidden anywhere in the Lake Monroe watershed for this entire year because of a toxic (to humans) algae bloom. The lake was also much warmer than usual.

But this is a case where there has been a significant differential impact on the metric of “differential survival until reproductive maturity” that is clearly strongly correlated with the color of the oysters. Red oysters have increased in frequency from 30% to 80%, with a concommitant decrease in blue oysters. All in the absence of human intervention. Completely in the absence of any known conscious “designer” or intent. This is an example of what Darwin meant by “natural selection”. And, not surprisingly, it also meets the requirement of “differential reproductive success due to alternative phenotype” seen in the modern definition of NS. A simple chi square test shows the probability of such a difference occurring by chance to be much less than 0.01%. That is, the difference in the “differential reproductive success” (as measured by differential survival to reproductive age) is statistically significant.

A biologist might hypothesize that this example of “natural selection” might be due to the red oysters being more resistant to the toxin of the algae or to a temperature effect (directly or indirectly), but identifying or even correctly identifying the cause is not necessary in declaring that this meets the requirement of being “natural selection” ala the idea described by Darwin when he used that term. All that is needed is evidence to support that this is significantly different from the expectations of chance alone (that being described in Example 1) and not known to be the intentional product of a conscious agent.

 To summarize: This is an example of “natural selection”, that is, significant differential reproductive success of one phenotype rather than the alternative in the absence of human intervention in a specified environment (Lake Monroe that year). It is the absence of conscious human intervention that makes this “selection” “natural” rather than “artificial” in Darwin’s terminology. Because there was no observable “designer” involved that had the intent or consciousness of selectively changing the ratio from the expectations of a “random pattern”, one cannot call this example of “natural selection” “design”. The result due to this “natural selection” is a “pattern” and specifically a “non-random pattern” because of the differential selection and the absence of a designer.

Your turn: Do you agree that the above example is an example of “natural selection” as that term was used by Darwin?, both because it involves selection and because it does not involve humans (and thus is not “artificial” by his usage). Do you agree that it is NS as defined and ideated by modern biological scientists? Do you agree that this is an example of a “pattern” rather than “design” because of the absence of a human or other designer’s involvement and also that it represents a “non-random pattern.” Explain.

Example 3: Start out with the same 30/70 red/blue ratio. But now we introduce humans who love the blue oysters and, in fact, are part of a Blue Oyster Cult. The Blue Oyster Cult has observed the life cycle of oysters, and consciously recognize that if they go to the Gene Poole Pond and prevent the shit-tasting red oysters from reaching the pond, that they will have more of the delicious blue kind. So they frantically remove red oysters (and compost them). Only 1/6th of the starting 30% red oysters still manage to reach the pool. That is, the ratio of new oysters in the pool is now 5 to 70 (7% to 93%) red to blue. The next generation to reach the pool is now also 7%/93% (indicating that, in the absence of the human intervention, the traits were indistinguishable from being selectively neutral wrt each other; in this case we can rule out “stabilizing selection” by heterozygote advantage). This is an example of what Darwin meant by “artificial selection” and represents a significant conscious change in frequency due to the conscious actions of humans to selectively favor the blue feature over the red.

 This would be an example of “design”, as would any example of conscious “artificial selection”.

 Your turn. Do you agree that this is an example of “design” by your understanding of that term and “artificial selection” as it was used by Darwin? Do you agree that the defining feature of “design” requires the involvement of humans or other animate design agents (at minimum, although I would add that the design agent perform its selection via conscious action)? Explain, especially if you have some other way of consistently identifying design that does not require knowledge of a designer.

The above 3 examples are rather clear cut. And they cover the typical examples of NS, AS, and selective neutrality. Of course, as in all of science and science based on induction and statistics, all conclusions of randomness and non-randomness are tentative and one can have marginal cases where one is not sure if the result is due to randomness (aka selective neutrality), natural selection (non-random and without a designer), or artificial selection (non-random due to the conscious action of a designer agent).

We have already mentioned the possibility of a designer consciously trying to mimic a non-selective result, and pointed out that that is difficult for humans to achieve. And pointed out one possible “selective” mechanism (heterozygote advantage) that might mimic “selective neutrality” temporarily if one did not know the genetics of the system. That is part of the reason why scientific explanations are always tentative and subject to change in light of further evidence. Similarly, we might reconsider an example of “natural selection” if empirical evidence presented itself of a likely designer.

But there is at least one other example that is ambiguous. Namely selection by a designer agent who is unconscious or unaware that he is producing a non-random result. And this example has been seen in the real world wrt the size of fish at maturity.

Example 4: As in the other examples, the starting population is 30% red and 70% blue oysters and that is also the %s of the offspring that enter Lake Monroe to mature. But now humans, who dearly love the blue oyster taste have, instead of doing selection to increase the frequency of blue oysters as in Example 3, harvested mature blue oysters in Lake Monroe just before the time of year in which the oysters walk to the Gene Poole Pond to mate. They put the blue oysters in their pots, stewily, and toss the red oysters back because they love to eat the blue ones and are disgusted by the red ones. The humans ignore the oysters after they leave Lake Monroe and walk to Gene Poole Pond. Not surprisingly, the % that reach the pond now are changed, to a significantly different 50% red and 50% blue, because of the selective harvesting of blue oysters by humans.

 Thus the next generation of oysters is now 50:50 red:blue instead of 30:70 and there are fewer and fewer blue oysters and more and more red ones in Lake Monroe, greatly increasing the value and cost of blue oysters. This is pretty obviously not the conscious intent of the (rather ignorant) humans harvesting the oysters, since it means that there will be fewer and fewer of the desirable blue oysters. But it superficially is “artificial selection” both because it is due to human involvement and represents differential non-random selection of the alternative types of oyster. So is this an example of “pattern” rather than “design” because the selection was not consciously done to produce the result but the result was an inadvertent consequence of selective predation done without thought or intelligent foresight as to the consequences (which are opposite those a sentient human would want)? Or is this an example of “design” because it is a non-random result produced by an active designer agent, even if that result was not the intent of the designer? Perhaps “artificial selection” should be restricted to those that humans do consciously for their own purposes, like making toy poodles because they are cute and sheep dogs because they are useful to shepherds.

Unconscious selection by differential predation without intent to selectively breed, might better be considered “natural” even though done by humans, just as it would be if done by wolves. Unlike the other examples, which are pretty clear cut, this one is more ambiguous and I could support calling this either “design” or “pattern” depending on the particular definition of those terms one is using. If you limit “design” to those patterns consciously produced with that pattern as the intent of the designer, then this is not “design”. It also means that anthills and aphid slaves are not “design” because the organisms that design those do not have consciousness, but only instinct. But feel free to make an argument for one or the other. All I ask is that you be consistent, if you can.

 

Example 5: Invent an invisible undetectable superintelligent and omnipotent agent that can produce whatever it wants and whatever can be observed without itself being observed. Explain all or any random subset of the other examples as being due to the actions of this invisible and undetectable agent; thus everything is due to the actions of this unobservable agent. Is everything then “design”? Or are there still some results that are only “pattern”? Which are they?

 And tell me why Example 2 (“natural selection”) is a tautology?

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21 Responses to Classifying Selection as Natural, Artificial, Neutral or by Design

  1. Eugen says:

    Oh for God’s (Darwin’s) sake! That guy can type. Lots to read, I’ll finish it tomorrow.

  2. ogremkv says:

    He did say he goes on a bit 🙂

  3. Eugen says:

    Simple scenario

    100 members of one species lived in a warm little pond. Suddenly climate changed for colder which killed 50 of them. Surviving had small genetic variation which gave them advantage to survive. The rest of the 50 members continued reproducing after passing through the natural selection filter.

    This is plausible scenario which matches my and most likely your understanding. Yes?

  4. ogremkv says:

    Up to a point, I would agree. I’d like to say that ‘sudden climate change’ is a discussion of hundreds of years, which might mean millions of generations of the organisms.

    There is also no gaurantee that the alleles for the non-cool climate change organisms don’t still exist. Maybe the resistance to cool is a recessive trait.

    But other than that, yeah, I can see it.

  5. Eugen says:

    OK, maybe you already answered my question.

    I was wandering if random mutation only can provide for needed adaptation which allows survival in cold climate. I don’t think that cold climate adaptation is matter of few random mutations but probably groups of specialized genes. Sudden climate change could mean few hundred years but maybe even only one hundred.

    Is that enough time? Another thing is could there be a cold climate “pre adaptation” set but that implies design.

    This is just my “loud thinking” as I know only basic biology.

  6. ogremkv says:

    Eugen, there’s no reason that cold adaption couldn’t be “pre-evolved”. In other words, a few hundred thousand years ago, a mutant appeared in the population that conferred some advantage in the cold (colder than just winter). However, it never got that cold, so the mutation never was ‘needed’.

    Through just gene flow and genetic drift, the cold gene became fairly common. Then, when the cold hit, half the population was ready for it. No design required.

    Of course, as Lenski’s work showed, organisms don’t have to have that pre-prepared either.

  7. Eugen says:

    There you go, I don’t know anything about Lenski.
    I’ll think up some questions later if you are willing to answer without getting into too much arguing.

    Ogre, let me ask something else first which you don’t have to answer if it’s too personal. May sound silly but what do atheist do during Easter holidays? Is it just another weekend for you? I don’t know any (confessed) atheist personally , only online.

  8. ogremkv says:

    Other than going to church when I was younger, the Easter holiday is the same as everyone else. We dye Easter eggs, hide them for the kids to find, have a big meal with all the various family. The same as other holidays.

    What’s very interesting about Easter is that it falls at about the same time as Beltane, which is the pagan Spring celebration.

    Many of the Christian holidays have a specific purpose (usually related to the time of year and developed from 400AD to about 1400AD) and they are pretty much the same holidays that the pagans (a generic term for all animist and druidic religions) had and have.

    When you look at it as a celebration of Spring, the rebirth (if you will) of life from the deep, dark winter, it makes perfect sense, even for an atheist. And, like I mentioned, they are a convenient distance apart for the family to get back together again.

    As far as Lenski, he’s the guy that has been stressing E. coli for the last 20 years. He’s got 30,000 generations of these guys in storage. The initial experiment was to see if the E. coli population could evolve a system to use citrate as a source of energy (one of the defining characters of E. coli is that it cannot do so).

    I don’t recall offhand, but about generation 25,000 or so, a population emerged that could use citrate. Since Lenski and his students had kept every line and a batch of individuals every 20-100 generations, they were able to trace the exact sequence of changes in the bacterial DNA that led to the ability to use citrate. No design was seen at any point in the lab.

  9. Eugen says:

    OK it’s nice to keep Easter traditions. I’m Catholic and I can assure you it’s all about keeping tradition for us including processions when we show off pictures, statues and parish insignia. I know well that many Christian holidays coincide with old pagan ones. Rome switching to Christianity was as much political move as sincere one.

    Hey I tell you what : if you ever want to convert, pick Catholics. Look at this – Vatican is rich so you don’t have to donate much. If you don’t go to church nobody will bother you. There are no restrictions on food and drink. If you steal something just do confession. How easy is this and bonus! you get the front row seat with the Boss In The Sky.( hope I don’t go to hell for all this)

  10. ogremkv says:

    Sorry, the Catholic Church offends me on too great a level to even consider joining that monstrosity. But thanks for the offer 🙂

  11. Eugen says:

    Yea, I was kidding. 🙂

    What could Catholic church possibly do to offend you so much?

    When you mentioned e coli experiment I remembered reading about it and Lenski.

  12. ogremkv says:

    1) Telling my wife and I that we couldn’t get married.
    2) Aiding and abetting child molesters.
    3) Emotionally harming children and adults.
    4) Allowing preventable pain.
    5) Preventing both contraceptives and abortions.
    6) Creating a continuous cycle of need and giving instead of promoting self-education and advancement.
    7) The Middle Ages
    8) Playing both sides in major conflicts (i.e. refusing to stand up for their own principles)
    9) Incorrect history
    10) Papal infallibility
    11) Index Librorum Prohibitorum
    12) Made up theology

    For an organization that is supposed to be Christian, they do a heck of a lot of damage to society.

  13. Eugen says:

    I don’t blame you for being p-off on some points you above. I’m not happy with some of them, either.
    In any huge organization there will be struggle for power and prestige, greed, abuse etc.. For ex. same happens with corrupted politicians, police officers selling drugs, teachers sexually abusing kids…..We have to look for how prevalent it is. In any of these examples problems are rare. It should not be acceptable but it happens and we have to live with it as long as it’s controllable.
    Obviously some problems are worse than others.

    In case of Catholic church ,child abuse should ‘ve been handled harsher. Any abuser is a criminal and should go through justice system.

    Some of the points above are just rules you may not like. That brings me to my (hopefully) humorous “commercial” about joining Catholics. Everything looked fine and dandy but I forgot to mention rules come in a small print at the bottom of the page.

    Other issues on history, education and ethics are debatable. It’s possible I would agree with you there on some points.

  14. ogremkv says:

    I have no truck with individual Catholics. Most of my wife’s family is hugely Catholic… so much so that they can’t seperate themselves from criticism of the church.

    I just want it stated plain, I’m critizing the church and its policies, not the people. Though I do think that the people in the church have a responsibility to see to it that the church lives up to expectations and if it doesn’t then, they should leave or actively try to effect change within the organization.

    For example, I would be totally POed if my tithes were being used to pay off the victims and lawsuits resulting from child molestation by priests. If all Catholics in the US said, no more tithes until this issue is resolved, then the church would take care of it. The people could send that tithe money to Red Cross, the ASPCA, or whatever other charity organization they wanted to until the Church resolved it’s internal policies and issues.

    But most people jsut accept it and that offends me about the people. Nothing will change until the majority want it to change.

  15. Eugen says:

    Religious organizations are not very democratic but if enough letters and e mails are sent they’ll take notice. That’s probably the only influence members have.

    I can understand people not wanting to belong to organized religion. It’s harder for me to understand person not accepting God’s existence.

    All this is without judging them as I have my doubts and struggles with the issue of pain and suffering humans have to endure. Why so much suffering?

  16. ogremkv says:

    hmmm… that’s a fair question. Here’s what you might do. Watch two episodes of “Life of Mammals” I think it’s on netflix for free, if not the BBC should have it available too. The episodes to watch are ‘Predators’ and ‘Primates’.

    Compare the suffering a Zebra being eaten alive by a pack of lions to human suffering.
    Compare the behaviors of non-human primates to humans.

    I think that you will find that suffering isn’t merely a human condition. It is a constant condition in the struggle for existance. We are inured to suffering because we don’t really see suffering in our day to day lives. My boy thinks I’m being unimaginably cruel by denying him TV time on weekdays. Of course, he’s never gone hungry, he’s never had to survive in the heat or cold without shelter and appropriate garmets. He’s never had to fight 4 or 5 siblings for a morsel of food. Etc… things that a goodly number of humans and almost all animals deal with on a daily basis.

    Evolution/science actually predicts this. There are limited resources and way more offspring than can survive. (In fact, those are two statements that led Darwin to natural selection.) Everything is in competition with everything else for everything. The ones that don’t win… suffer (for some values of ‘suffer’). Humans are no different than any other living thing.

  17. ogremkv says:

    Oh, as for not accepting God’s existence… which God? Last I recall, there are something like 30,000. And that doesn’t include the animist and ancestor/gods.

    Might there be a god? Sure, I don’t deny that there could be a god (for some value of ‘god’). Of course, it’s equally likely that we’re all in The Matrix too. In fact, I would submit that the Matrix notion has a little more support in that we know extremely powerful computers can be built. We have no evidence of any kind of the existence or powers of any god.

  18. Eugen says:

    I know zebra being eaten alive is suffering pain.

    It’s little different for humans. We know consequences of the pain and suffering ,animals do not. We know there’ll be no tomorrow or a next week , animals do not. We are not sure what happens when we die, animals don’t worry about that.

    Friend of a friend is in her 40s and she’s being “eaten” by cancer from the inside for months. She will leave 2 kids, husband etc..when she goes. That is suffering beyond imagination.

    Re. living in the Matrix.

    Recent research and theory on nature of reality are pointing to something amazing. It seems everything exists in some form of matrix. It’s a framework of interacting layers, a superconductive substrate for support of space-time. Huh? Is this some New Age crap? No, physicists are proposing this based on recent data and calculations.

    I finished reading book on that, it’s very difficult to understand. Trick to do is leave it alone for few months and than read the book again. Second reading provides much more understanding.

  19. ogremkv says:

    I disagree, I think that animals (some at least) can conceptualize pain/suffering and the anticipation of it. Just think about trying to get a dog into the vet’s office. He loves getting in the car and driving, but freaks out when you pull into the vet’s parking lot. It is known that chimpanzees and bonobos can feel something approaching empathy for a dead or dying member of their tribe. They understand suffering. Most animals don’t bitch and cry about it as much as humans do though. 😉

  20. Eugen says:

    I think they would even worse if they understood the consequences 🙂

    Anyway, I see you’ll have debate with Joe. Good luck to both of you.

  21. Pingback: Stabilizing Natural Selection Definition

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