Saturday, 1 September 2012

Bad Evolution 2 - 'Bird Funerals'

A while ago I threatened to start a series on 'Bad Evolution' - not because I disagree with the principle that things could 'evolve', but because the way that evolutionary matters are presented in the public domain often shows an ignorance of basic Darwinianism, even whilst it seeks to promote it.

Thus the BBC (who are often the perpetrators) served up a good one today in a story on 'bird funerals'. Apparently, when Western scrub jays discover the dead body of one of their kind, they fly down and gather round it.

And then comes the 'bad evolution' bit: "The behaviour may have evolved to warn other birds of nearby danger, report researchers in California, who have published the findings in the journal Animal Behaviour."

The problem is, of course, the word "to", as in "The behaviour may have evolved to warn other birds", because in the 'standard theory' there is no 'to' or 'so that'.

The 'standard theory' of evolution, as I understand it, is that a fresh characteristic - in this case a particular behaviour - conveys a significant breeding advantage in those organisms possessing that new characteristic, which means that more of them come to exist over time.

So we could say, "When this behaviour emerged amongst jays it may have resulted in a greater breeding opportunity for those bird populations in which it warned others of nearby danger and allowed them to out-breed those populations which did not possess this characteristic." Not nearly as succinct as 'to', but not as misleading either.

Of course we also have to presume that this was a population phenomenon, because the birds 'being warned' are not necessarily the same as those doing the warning, and I can see how the former might have gained a breeding advantage, but I wonder about the latter. In fact, I would have thought flocking round a dead body, if the death was the result of disease or predatory action, was likely to mitigate against more breeding opportunities, since you were more likely to become infected or get eaten. But presumably it must have worked something like what is being suggested. (Or maybe 'compassionate' birds were perceived as the sensitive kind and could more easily get mates -- who knows?)

Incidentally, I think I am right in saying that 'survival' per se can never be an evolutionary driver, since it merely means you stay the same but don't get eaten, starved, drowned, fried or whatever. It is not 'survival' that produces change, but a fresh 'advantage', which must also be a 'significant' advantage in the sense that you actually breed more so as to pass on the new characteristic.

This is why the 'gradual change' scenario has to be nuanced. It is all very well saying that the eye, for example, could evolve by numerous small steps, but each small step still has to be big enough to convey an actual breeding advantage.

The definition of 'how small' an 'evolutionary' change needs to be is not 'small enough to be different from the previous form of the eye' but 'big enough that the organism with the new form is better equipped than its parents and cousins to the extent that it breeds more'. Remember, we are talking about 'natural selection', and the natural selection must be not what survives but what excels. At least, that is what I've understood.

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  1. Nicely put, John. The survival bit is interesting. If a creature doesn't survive, then it doesn't even get off the starting blocks for breeding. So survival per se is not a driver, but it is required before one can breed. Survival is necessary but not sufficient. Advantage in survival or breeding will produce more offspring, won't it?

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  3. Revd John, I am no expert in Evolutionary theory. However as understand it does not wholly revolve around the issue of ‘significant breeding advantage’ for ‘organisms possessing that new characteristic’. This is a gross simplification – a characteristic or behaviour may simply give rise to an organising having a better chance of survival (particularly when there is a change in a given environment). Thus when buildings became sooty in the 19th century the peppered moth, then mainly light in colour, because it rested during the day on walls and tree bark, became easy meat for birds. However a small proportion of the population had a chance mutation that made them darker in colour and these survived and bred and this characteristic became the dominant colour of the moth until clear air legislation gave lighter coloured moths a fighting chance to breed once more. To state this is a ‘breeding advantage’ would be incorrect, it is just more of this or that coloured moth survived to breed. I am afraid to state: ‘a significant breeding advantage in those organisms possessing that new characteristic, which means that more of them come to exist over time’... is itself, bad evolution!

    (too many typos in my first attempt at posting this!!)

  4. Rev Stephen Bazlinton2 September 2012 at 23:43

    All that Kettlewells experiments with Peppered Moths showed was that Peppered moths changed colour in different environments. Genetic information was lost and melanisation occured giving them an advantage in sooty conditions. (There has been some dispute about his 'fixing ' of the original research). The Peppered moth remained a Peppered Moth, it did not morph into a swallow tailed butterfly. In natural selection, information is not gained, it is lost as a result of mutations, and this may be favourable to survival or not. The flightless cormorants of the Galapogas are still cormorants but have lost the information to form 'flyable' wings.
    Much of the reasoning about why this or that change took place seem to me top be simply 'just so stories'. Not based on observation but imagination.
    The big problem is whether natuarl selection on its own is able to make man or infact any other living thing out of molecules.

    Stephen Bazlinton

  5. Peter, I'm afraid, yes, that is 'bad evolution'. The experiment to which you refer has been a matter of dispute for some time, though in my childhood it was offered as a classic 'proof' of natural selection.

    Even at face value, however, there is no 'evolution' involved. As you (and Stephen) observe, the darker moths were there already. (To say there darkness was a matter of 'chance mutation' begs the question. You might as well say the light ones in the same population were a 'chance mutation' as well - in classic theory, all genetic information is as much a matter of 'chance' as any other.)

    The point is, in this instance, darkness was not new. Merely surviving, then, could not be said to have resulted in a 'new kind of moth', just more of the same.

    You said, "To state this is a ‘breeding advantage’ would be incorrect, it is just more of this or that coloured moth survived to breed." (My emphasis) Well, that is a breeding advantage by any other name.

    Incidentally, my point here is not to cast doubt on evolution per se but to question the way it is understood and presented. Eg the notion that 'many small changes' can easily be envisaged to produce the eye. As I've said, there is a level at which a conceivable change would be too small to work.

    In the (perhaps hypothetical) moth instance given above, the difference was not small!

    One of the issues, for example, is that the mechanism of natural selection is not the same as evolution. Ie where natural selection is operating, there may not necessarily be any evolution going on. The Dodo was eliminated as a result of natural selection - the problem being that all the Dodo population was selected.

  6. Chris Illingworth3 September 2012 at 21:17

    In one sense the need for survival can result in an observed change in a population, such as when there is a change in environment. It may be that, in one environment, types AB, Ab, and aB of an organism are seen, the ab individuals not surviving to be observed. Following a change to a second environment, the ab type might become advantageous and take over the population, to the extent that the AB, Ab, and aB types no longer exist.

    What survival cannot do is create new variation in the population that was not (potentially) already there. Variation arises through mutations, (e.g. from ab to Ab), which increase the number of types of individuals that can potentially be born. Selection (as in which individuals reproduce), changes which of the potential types are realised in the population (often removing other potential types in the process).

    The size of an evolutionary change has a 'minimum size' in the sense that at a discrete change must happen to a genome (at least one nucleotide changes, or is added, or deleted). However, given enough time, a mutation with a very small advantage (across the set of circumstances organisms encounter) would under most circumstances be expected eventually to spread to all individuals in the population.

    In terms of what does spread through the population, a mutation doesn't strictly have to provide an advantage. If a mutation has no effect at all on an organism, it could still take over, purely through time and chance. If a population is small enough, a number of the mutations that get through may have a mildly deleterious effect.

  7. Stephen Bazlinton3 September 2012 at 23:10

    A good friend of mine a professional geologist, made the following comment on this comment of yours, John:

    Of course we also have to presume that this was a population phenomenon, because the birds 'being warned' are not necessarily the same as those doing the warning, and I can see how the former might have gained a breeding advantage, but I wonder about the latter."

    'This raises the whole question of how evolution might have given rise to altruistic behaviours. I think one solution (from an evolutionary perspective) is to argue that what is being selected for (or against) are genes (and the traits they encode) rather than individuals. Close relatives are likely to carry similar sets of genes and so it is argued that some behaviours evolved because they promote the survival of near-kin. Perhaps that is the evolutionary explanation for this "warning" behaviour in jays? Stephen Bazlinton

  8. Revd John

    Thanks for you comments - which were helpful.

    I think sometimes we just have to accept that it is impossible to summarise something as complex as Evolution in a comment on a blog!

    One thing I have noticed again and again with those who like to debunk (or at least call into question) Evolution is that there seems to be a desire to remain rooted in human time scales. Or they – not unlike Christians scouring the Bible for this or that verse to provide weight to their personal or political views – pick out the bits they like that add weight or emphasis to their particular take on Evolution (be that positive or negative).

  9. Dear John

    I feel sure that eventually we will see that the evolution scam will be debunked as surely as the Co2 = global warming myth.

    We will accept that Natural selection can take place, but a dog remains a dog etc and a dog cannot change into a cat. There is still no evidience to support speices change by evolution.

    For Christains there is a darker side of course. Evolution and Eugenics are natural bedfellows. Look at how the Nazis used Darwin. If you belive in evolution then what the Nazis did makes perfect sense. Indeed you read that after the war many of them did not see what crimes they had commited as what they had done was the "natural order of things"!

    Of course abortion evil dwarfs anything that the Nazis did. But we are OK with this because we are just getting rid of potentially disabled or undesired people.

    The whole thing is not just wrong it is evil


  10. Furthermore

    In many school textbooks your have the "proof" of white moths on whote branch and black ones on a sooty one with the photos side by side.

    Fine till you find out that white moths will not lland on tree branches but prefer the undersides of leaves. So to get the photos in school text books. white moths had to be glued onto the white branches!

    see the controversy section...