Showing posts with label darwin. Show all posts
Showing posts with label darwin. Show all posts

Saturday, 31 January 2009

More on Neanderthals

I was pointed at this account of a refutation of the commonly held view amongst the scientific community that Neanderthals are a separate species of hominid (indeed, of the genus Homo). I have many issues with both the premises as presented and the conclusions drawn. In fact, every paragraph seems to have at least one thing I feel is wrong or misunderstood. Below each paragraph I have tried to show which items I believe are fallacious premises, which are non-sequiturs as conclusions, and which are misrepresentations of facts.

Neanderthal Men Were Modern Men
by Brian Thomas, M.S.*

A set of fossilized human remains has been discovered in Iberia that shows partial Neanderthal characteristics, proving again that Neanderthals interbred with anatomically modern men.1 This adds to a growing list of evidence, consistent with biblical history, that demonstrates Neanderthal to have been fully human, rather than an evolutionary transition.2


Ref[1] indicates that this is the Sima de las Palomas find. Apparently this is dated to 40,000 years. Also seems like the site has only Neanderthal remains, unless it's not stated in the abstract that there are also 'modern' humans (i.e. Homo sapiens). “The human fossils from the upper levels of the Sima de las Palomas are anatomically clearly Neanderthals, and they are now securely dated to 40,000 years ago.”[ref] From the reports on this find[ref][ref][ref], none other than this one mention “partial” Neanderthal characteristics.

After writing the above paragraph I went and did some more digging, and found this which does say that the PNAS article mentions characteristics similar to modern humans. One of the two explanations it says are put forward in the article is that there was hybridisation. However, Antonio Rosas, an expert on Neanderthals, says that he does not believe the find demonstrates this hypothesis, saying "The variation seen in the Neanderthals they have found can be explained without hybridisation. Genetically, there is no data that exists to affirm this hybridisation, and the genetic separation between modern humans and Neanderthals is very large."

What I understand from the abstract of Ref[2] (that does indicate a “mosaic of European early modern human and Neandertal features”) is that this is suggesting that the two groups lived alongside each other rather than the Homo sapiens population overrunning (and hence replacing) the Neanderthal populations in the Late Pleistocene (which it implies was the prevalent current conjecture). Nor, as the author of the article appears to (erroneously) believe evolution claims, that the Neanderthals died out, and modern man replaced them with no overlap.

Why does commonality of features prove them to have been “fully human”? What does “fully human” mean? They are fully human in the sense that they are within the genus Homo… In exactly the same way that both they and ourselves are hominids (in the family Hominidae or "Great Apes"), along with the genera Pan, Pongo and Gorilla.

Though evolution models once held that Neanderthal man was one of the “missing links” between an ape-like ancestor and modern man, the repeated discoveries of Neanderthal remains right next to those of modern humans—instead of in separate, lower, older strata—have forced him out of the pool of “pre-human” evolutionary ancestor candidates. In contrast to ever-evolving naturalistic interpretations, the biblical creation model has consistently maintained that Neanderthal man was just that—man.


Evolution also claims that Neanderthal is a form of man, and that Homo neandertalensis and Homo sapiens split off the same branch of human ancestors. Evolution does not describe a ladder, but a tree.

Ancestors can still co-exist with descendant species. Think of mud-hoppers – fish that have changed very little from those fossils of trasitional forms such as Tiktaalik. Also think of a great-grandfather living at the same time as his great-grandson. They are related, but one is several generations younger. Think also that there are many branches from the great-grandfather, and some of his offspring may look more like him than others. And of course, even more appropriate, a man's granddaughter and grandson will be alive at the same time. While my examples cover a very small time-period, the principles are still the same - two separate lines will be alive at the same time. The Neanderthals died out - but that does not mean they were not around at the same time as Homo sapiens. Indeed, they *must* have been at the start of the divergence of the two species.

In fact, it is the data that tell us that some forms of man followed on in a somewhat sequential manner, because one appears to have died out shortly after the inception of the other. The theory of evolution does not predicate any such sequence.

Neanderthal did have distinct characteristics that are apparently now either extinct or diffused, but his family line was fully human for several hundred years after Noah’s Flood, when humans repopulated the earth about 4,300 years ago.


The Iberian find is dated to 40,000 years. Most Neanderthal fossils are in the order of 50-60 thousand years old. How does this statement reconcile itself with the evidence that the author has already presented?

The mounting evidence for Neanderthal and modern man’s coexistence calls into question whether the Neanderthal and other human varieties even lived in separate times, as the evolutionary story still maintains. Both the Bible and science indicate that this was not the case. Biblical history has no place for such a separate, distant time of evolutionary development, but it does allow for variations within the human kind in its 6,000-year history.


"The mounting evidence" presented here appears to be one reference, or perhaps two. And I don't think that even these really debunk anything in the theory of evolution or common descent.

The "evolutionary story" maintains that "human varieties" lived at separate times? See above. This is at best a dubious statement, if not completely fallacious.

Anthropologist Marvin L. Lubenow has shown that Neanderthal, other than having a larger cranial capacity, was anatomically the same as Homo erectus.3 Their fossils do not fit into the depiction of a linear evolutionary ape-to-man transition that is iconic today, but were simply comingling variations of humankind. Furthermore, a fossil elbow (KP 271) and the Laetoli footprints of Neanderthal man are indistinguishable from modern man, and both have been dated by evolutionary scientists at 4 million years or older—predating the earliest Neanderthals!4 Thus, within the published evolutionary dates, “anatomically modern Homo sapiens, Neandertal, archaic Homo sapiens, and Homo erectus [as well as Lucy-like Australopithecinces] all lived as contemporaries.”3


Again, see above – evolution does not claim a linear transition. It claims common descent - i.e. a common ancestor.

"Comingling variations of mankind". Indeed. There is a possibility that contemporaneous varieties and species within the Homo genus might have interbred, although the further apart they are, the less likely that is. One of the common lines in the various definitions of species is that they cannot (or do not…) interbreed, or that if they can, they produce infertile offspring. HGT may also account for some intermingling of DNA; I have not looked at how much influence this is thought to have. If the evidence does point to both Homo sapiens and Homo neandertalensis co-existing (I don't think the references here cited do, but I don't think it's impossible or unlikely), that would not mean that the evolutionary theory was incorrect.

As for the Laetoli footprints are not believed to have been made by H. neandertalensis. The wikipedia entry suggests that they were made by Australopithecus afarensis. Encarta agrees with it being A. Afarensis. Another opinion is presented by William E. H. Harcourt-Smith, who doesn't actually say what species made the footprints, but does point out reasons for it not necessarily being A Afarensis as nearby remains might suggest. The one tentative alternative is A. anamensis (http://www.sciam.com/article.cfm?id=footprints-to-fill). The reason the footprints look similar to those made by modern man is because they are made by hominids which walked in a similar, upright, bipedal stance. This does not mean that they are H. sapiens. Or indeed even within the genus Homo, as A. afarensis appears to be main contender. That there is contention about them suggests that they certainly are different in some respects to modern humans' footprints. The similarities - which are what prove that they belong to a bipedal animal - are the arched foot and the forward-pointing big toe.

The overlap of species appears is depicted here. Yes, there are overlaps - exactly as to be expected, as explained above.. (see also this talkorigins page)

As seen in the fossil remains from Iberia, the more that is discovered about Neanderthal, the more evolutionary models morph to accommodate the data. In contrast to this ambiguity, both the Bible and science confirm that man and apes—though many small differences can be discerned within each kind—nevertheless remain totally separate, untransitioned created kinds.


"The more evolutionary models morph to accomodate the data". Well, that is how science works. The more data you get, the better your theories become. If there is something that doesn't fit, then you have to change your ideas. However, if the rest of the data can be accounted for by the existing theory, and there is some slight deviation in this data, then only a small change is needed. If the deviation is huge, then perhaps a different theory is needed. Everything so far seems to fit the theory, or the former example. None of it has so far so catastrophically refuted the existing theory that it needs major revamping. Even things like relativity didn't change Newton's theory of gravity, as it described the existing data perfectly well.

Friday, 30 January 2009

99% Ape - ch1: 99% Ape

Mutations in HIV


A diagram showing the tree of mutations in a strain of HIV in a dentist and four patients is given on p.9. The text says that patients A, B, and C were shown to have received the virus from the dentist, but that patient D was not.

The diagram, however, shows that the mutation that lead to patient B's virus strain occurred 'before' that of the dentist (or, at least, that the differences between it and the dentist's strain suggest an earlier divergence). What was the conclusion wrt patient B?

Evolutionary Trees


Q: Where did HIV come from?

A: HIV and SIV (Simian Immuno Virus) are closely related [[M] by examining their genomes?]

Q: Where and how did SIV develop? Since when is it known to exist?

Darwin, Apes and Victorians


Biblical account of Genesis
  • Humans created in God's likeness.
  • Species separately created ("Special Creation")
  • Each 'type' of animal is fixed
    • Similarities show design plan commonalities


    Darwin saw similarities as a consequence of evolution.

    Alfred Russel Wallace in 1859 was going to publish his theory. Darwin said it was "an excellent short abstract" of "On the Origin of Species".

    Evolution - the idea - was not invented by Darwin. Many others before him believed that species changed (such as Erasmus Darwin 1731-1802)

    Joseph Dalton Hooker - friend of Darwin's to whom he wrote about his initial thoughts on evolution.

    Darwin's contribution was to discover a method by which evolution works.

    While Darwin knew nothing of viruses, his theory perfectly descries how they change over time - one major piece of evidence for evolution by natural selection.

    Darwin's Insights


    The third point on page 14 states that the idea that evolution occurs gradually has stood the test of time. There does, as far as I am aware, appear to be evidence that, given the right environment (e.g. a new, unpopulated territory, or niche), organisms will evolve (diversify) rapidly to fill that niche, and then slows down once the 'hole' has been populated.

    What's in 1%?


    What are the counter claims against "99% similar"?
    They are based on other ways of measuring difference.
    Q: What are these, and how relevant are they?

    Many of the differences are likely switches which turn genes on or off - this allows a much greater effect than would be suggested by a small change.
  • Saturday, 24 January 2009

    Horizontal Gene Transfer

    A recent article in New Scientist talks about how Horizontal Gene Transfer (HGT) may well be a turning point in the Darwinian view of how life has evolved. It is pointing out that, from recent research, much of the genetic material in the eukaryotic and archaean organisms is transferred, not 'vertically' - by sexual reproduction - but 'horizontally', by swapping genetic material or by hybridisation.

    It further suggests that this also happens in the prokaryotic branch of the tree - that which includes the majority of multicellular organisms, including ourselves. It points out that methods of horizontal gene transfer might occur through mediating viruses which cut and paste genetic material between hosts. It can also occur via hybridisation, where two separate species cross. This, according to Loren Riesberg, is the case for about 14% of plant species. There is also some evidence that this may have happened in early humans, between our ancestors and concurrent species, such as Homo erecutus and Neanderthals.

    Personally I feel that some of this is a bit fuzzy. Firstly, the article suggests that DNA is subject to vertical transfer, but HGT can be seen in RNA. While perhaps that is just poor wording in the article, it feels from the first that the article is trying a bit too hard to make a point - and starts out almost hostile to the tree-of-life view, and so I wonder if it's trying to hide something there in order to prove a point. The article does ease up towards the end, describing the different viewpoints of scientists who feel that the tree of life needs to be 'uprooted' and those who feel that HGT just adds a new dimension to the data.

    As far as the hybridisation comments, it would seem odd that where speciating groups overlapped they did not hybridise to some extent if they were able to. In fact, I am fairly sure this is what Darwin talked about in Ch. 4 or 5.

    In the article it asks whether the tree-of-life view does not still apply to multicellular organisms. And replies - almost, at least - "Well, they aren't the majority, so we shouldn't bother with that view anymore". If the tree is still the way in which some genetic material is transferred, then, whatever other methods are available for its transfer, it is still a valid view.

    I kept thinking "Newton...Einstein" throughout reading this, and, sure enough, right at the end he says:

    If he [Michael Rose] is right, the tree concept could become biology's equivalent of Newtonian mechanics: revolutionary and hugely successful in its time, but ultimately too simplistic to deal with the messy real world.
    Some of the things mentioned in the article gel with my feelings about early life - knowing that single-celled organisms can only reproduce by copying made me wonder about how genetic variety worked before sexual reproduction occurred.

    I guess we live in interesting times - and I am sure the Discovery Institute is going to have a field day with this. It will be interesting to watch how it all develops.

    Monday, 19 January 2009

    On reading The Origin of Species: Ch. 4 - Divergence of Character (2)

    A lot is said in this section, and Darwin tries to put forth a solid basis for his reasoning that variation leads to speciation by giving a conceptual example.

    He suggests that if we look at a given point in time, we may have eleven different species within a single genus, "large within its own country" - i.e. there are many different species and much variation within each species of this genus in a given area.

    If we imagine that two of these species vary a lot, and produce, after many generations several varieties each, and these in turn produce multiple varieties, and so on up the ages. While at the same time most of the other species in that genus die off - possibly because the two which are varying a lot are doing so because they have some advantage, and start to occupy the niches that the other species were. And because they have this advantage, they perform much better than the other species that are not varying quite so much, and not producing offspring that can survive quite as well. But still these two species' offspring are also competing amongst themselves, and of course some of the varieties die off...

    After many thousands of generations, we might have eight variants of the first species, and six of the second species, and perhaps one of the original 11 species manages to survive through that many generations, also, but relatively unchanged. From Darwin's diagram on pp. 160-1 we can see that from the one species (A), out of the eight variants that have made it through, one group of three is fairly closely related, another group of two is also closely related, and a further group of three is closely related. We can also see that the latter group of three is more distantly related, and hence more distinctly different to either of the first two groups.

    A similar situation exists in the second species' (I's) progeny. We have two groups, each consisting of three very closely related varieties each.

    We can also see that these two groups will be quite distinct from each other, for not only were the ancestors whose progeny they are somewhat distinct, they have also accumulated differences as the ages pass.

    What's more, they are each somewhat closer to the species that descended from the other species, F, than they are to each other, by the fact that species A was more distinct from I than it was from F, and the accumulated variations are less likely to have brought them closer together than further apart.(*)

    He then goes on to point out that a naturalist looking today at the varieties would most likely lump the three groups descended from A into three separate sub-genera or genera, and likewise those of the descendants of I....In other words, they are separate species.

    (*) At least - I think this is what he is trying to say. I am not 100% convinced on this front, although I can see an argument for saying that the number of ways of diverging are greater than the number of ways of converging, thus statistically they are more likely to diverge than converge.

    After reading this chapter, I can still see how a creationist might claim that Darwin has not proven that speciation does actually occur. My other thought is that he is relying on variation which he has stated stems from sexual reproduction on which natural selection can then work. If we start with a single single-celled organism produced by abiogenesis, where does the variation come from? I guess we are relying on imperfect copying creating sufficient distinct entities quickly enough that natural selection eventually has something to work on.

    Thursday, 15 January 2009

    John Whitfield has a blog on the Origin of Species - a post per chapter as he goes.

    In chapter 2's entry he covers some of the ground I did in one of my earlier posts - about how Darwin views the definition of species. I particularly noted his comment:

    Here's some advice for anyone agonizing over creating a perfect, all-encompassing species concept: chill out. Pretty much any biological category you care to think of has fuzzy boundaries. Genomics is making the concept of the gene more problematic. Colonial, clonal and modular organisms, such as slime moulds, aspen, and the vast underground mycelia of some fungi, make the concept of the individual tricky to pin down. The giant mimivirus blurs the line between viruses and cellular life. There's been a long debate over whether viruses themselves should be classed as living things. And it's proved impossible to come up with a list of properties that unambiguously define life.

    This does not mean that terms such as species, gene, individual or life are useless. In many or most cases it'll be obvious whether the thing or group of things you're looking at belongs in a particular category or not.
    I shall post, asking for comments on thoughts about the utility of the terms...will at least enlighten me!

    Monday, 12 January 2009

    On reading The Origin of Species (ch 4)

    Darwin postulates that there may be a 'law of nature' that "a cross with another individual is occasionally - perhaps at very long intervals - indispensable [to increasing 'vigour and fertility']" as I mentioned in my last post.

    He goes on to talk about the methods by which flowers may be pollinated - pollination by bees and insects, either by them carrying pollen from the anthers of one flower to the stigma of another, or by triggering some mechanism that causes the flower to self-pollinate - for example by pushing its anthers against its own stigma as the bee or insect crawls into the flower to get at the nectar.

    He then goes on to note that in many flowers, such as Lobelia fulgens:

    ...either the anthers burst before the stigma is ready for fertilisation, or the stigma is ready before the pollen of that flower is ready, so that these plants have in fact separated sexes, and must habitually be crossed. How strange are these facts! How strange that the pollen and stigmatic surface of the same flower, though placed so close together, as if for the very purpose of self-fertilisation, should in so many cases be butually useless to each other! How simply are these facts explained on the view of an occasional cross with a distinct individual being advantageous or indispensable!
    He also says two things that seem somewhat at odds - and he hints at further coverage of the points later on. First off:
    ...if you bring on the same brush a plant's own pollen and pollen from another species, the former will have such a prepotent effect, that it will invariably and completely destroy, as has been shown by Gartner, any influence from the foreign pollen.
    Then a few paragraphs later:
    Yet the pistil of each cabbage-flower is surrounded not only by its own six stamens, but by those of the many other flowers on the same plant. How, then, comes it that such a vast number of the seedlings are mongrelised? I suspect that it must arise from the pollen of a distinct variety having a prepotent effect over a flower's own pollen...
    So...it appears to me that the principle is acting one way in one case and in another way in a different case - almost as if nature knows which organisms are distinct species, and which are distinct varieties....

    Saturday, 10 January 2009

    On reading The Origin of Species (ch 4)

    ...a cross between different varieties, or between individuals of the same variety but of another strain, gives vigour and fertility to the offspring; and on the other hand, that close interbreeding diminishes vigour and fertility...no organic being self-fertilises itself for an eternity of generations; but that a cross with another individual is occasionally - perhaps at very long intervals - indispensable.
    So...sex is necessary for improved vigour in a species...and what happened before species that had sexual reproduction? Or indeed with species that do not reproduce sexually now? Do amoeba not just split? How is it that they continue to have "vigour" and "fertility"?


    Further on Darwin mentions that he has not found one land animal that is perfectly hermaphroditic, and that although some marine animals are, that water currents can provide the means by which the occasional cross-fertilisation can take place. He mentions one species that he had initially had problems with - Cirripedes - but he found evidence that it, too, sometimes crosses.

    I am still not sure about amoeba and the like - is there any chance by which they can cross-fertilise?

    A final quote from Darwin on this:

    Finally, then, we may conclude that in many organic beings, a cross between two individuals is an obvious necessity for each birth; in many others it occurs perhaps only at long intervals; but in none, as I suspect, can self-fertilisation go on for perpetuity.

    Friday, 9 January 2009

    On reading The Origin of Species (ch4)

    ...but in all cases natural selection will ensure that modifications consequent on other modifications at a different period of life, shall not be in the least degree injurious: for if they became so, they would cause the extinction of the species.


    From other sources I know of the way that some genes can piggyback on the success of others just by being close to them on the genome(?). Now, I know that what Darwin said is generally correct, but I cannot see where he would have got that statistic without also noticing that there are also deleterious inherited effects.

    Natural selection obviously selects for the benefit of the beneficial gene, and not for the piggybacker's deleterious effect. And should the deleterious effect be worse than the beneficial effect, presumably it would be selected against. And of course it is all relative. When the environment provides a niche that selects for a particular benefit the piggybacker's effects are perhaps neutral....until such time as the environmental forces start selecting over the remit of that sort of effect.

    So what am I saying? Just that Darwin wasn't aware of genes and how his theory would get reworded once we understood more about how selection works on genes?

    I'm not sure! I'm just dumping my thoughts onto a post; there is no direction to them (yet?). I would like at some point to summarise everything I've written into a post that is more comprehensive, and perhaps actually has a point to make. For now, bear with the ramblings of my mind.

    Tuesday, 6 January 2009

    On reading The Origin of Species (p 126)

    The dependency of one organic being on another, as of a parasite on its prey, lies generally between beings remote in the scale of nature. This is often the case with those which may strictly be said to struggle with each other for existence [...] But the struggle almost invariably will be most severe between the individuals of the same species, for they frequent the same districts, require the same food, and are exposed to the same dangers.
    This is the start of the central point of chapter 3 - The Struggle for Existence. He goes on to point out that the struggle between varieties will be almost as severe, and (I am guessing, now, as I have not read much further yet) so decreases as you move further away on the 'tree of life'.

    The struggle for existence has previously in the chapter been demonstrated to be the major check on population; different species competing for the same resources, and particularly how different species which were previously deprived of a share of the resources available by a more successful organism, when that organism is removed, begin to thrive.

    Saturday, 3 January 2009

    On reading The Origin of Species

    p. 110

    Where many species of a genus have been formed through variation, circumstances have been favourable for variation; and hence we might expect that the circumstances would generally be still favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group haveing many species, than in one having few.
    In other words, and turning the statement on its head somewhat, where the environment (and/or other factors) have allowed an organism to diversify and we find many different varieties, we are more likely to find a greater variety of allied species of the organism than in the opposite case where the environmental factors have not been favourable to the diversification.

    Darwin goes on to make the case for this statement with real-world examples.

    On reading The Origin of Species

    It looks like Darwin was driving at exactly the idea I had had - presumably because I am actually understanding what he's saying!

    From these remarks it will be seen tht I look at the term species, as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety, which is given to less distinct and more fluctuating forms. The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, and for mere convenience sake.
    I still have to look up what the advantages of continuing to use this dichotomy (or, as Darwin points out, trichotomy - individual difference, variety, species) is. Convenience is an obvious candidate, as is custom - "we've always done it like this"

    Thursday, 1 January 2009

    On reading The Origin of Species

    Is the distinction between 'species' and 'variety' useful? Does it fuel the macro/micro duality?

    If we formally regard all organisms as 'varieties', then perhaps the macro/micro misunderstanding would be cleared up.

    Darwin notes on p. 105:
    A wide distance between the homes of two doubtful forms leads many naturalists to rank both as distinct species; but what distance, it has been well asked, will suffice? if that between America and Europe is ample, will that between the Continent and the Azores, or Madeira, or the Canaries, or Ireland, be sufficient? It must be admitted that many forms, considered by other highly competent judges as varieties, have so perfectly the character of species that they are ranked by other highly-competent judges as good and true species. But to discuss whether they are rightly called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air.

    What are the advantages of the distinction? Of classifying organisms according to genera, phyla, etc? The question perhaps sounds rather vacuous - of course labelling has utility. It allows communication. But what if the act of labelling things is actually causing a perceived either/or duality where none actually exists? What are the alternatives?

    On reading The Origin of Species

    p103-4.

    But cases of great difficulty, which I will not here enumerate, sometimesoccur in deciding whether or not to rank one form as a variety of another, even when they are closely connected by intermediate links; nor will the commonly-assumed hybrid nature of the intermediate links always remove the difficulty. In very many cases, however, one form is ranked as a variety of another, not because the intermediate links have actually been found, but because analogy leads the observer to suppose either that they do now somewhere exist, or may formerly have existed; and here a wide door for the entry of doubt and conjecture is opened.


    Darwin seems to have hit the nail on the head, here - this is where much creationist attack appears to stem from. They see all the evidence, but then say "but you're just guessing at the intermediate forms". Of course, we can nowadays compare DNA and the like, which (again) Darwin would have been most glad to have had. However, he goes on, in an effort to allay the problem raised by his last sentence:

    Hence, in determining whether a form should be ranked as a species or a variety, the opinion of naturalists having sound judgement and wide experience seems the only guide to follow. We must, however, in many cases, decide y a majority of naturalists, for few well-marked and well-known varieties can be named which have not been ranked as species by at least some competent judges.


    So...let's have a vote? Perhaps before the advent of being able to use DNA to place an organism on the tree of life by comparing its sequences to others already catalogued, this was indeed the best way. I suppose, in a way, the current strategy is also a majority vote - the majority of biologists agree that this method works as well as, or, in fact, better than, a rather subjective appraisal by a committee of naturalists.

    Wednesday, 31 December 2008

    On reading "On the Origin of Species"

    p. 99

    I believe that the conditions of life, from their action on the reproductive system, are so far of the highest importance as causing variability. I do not believe that variability is an inherent and necessary contingency, under all circumstances, with all organic beings, as some authors have thought. The effects of variability are modified by various degrees of inheritance and of reversion. Variability is governed by many unknown laws, more especially by that of correlation of growth. Something may be attributed to the direct action of the conditions of life. Something must be attributed to use and disuse.
    Some of this passage, the conclusion to the chapter on 'Variation under Domestication', confuses me. I get the impression that what I understand by variation is a more general meaning than that used in this passage.

    I also do not know quite what he means by "correlation of growth".

    I assume that by "conditions of life" he is talking about deaths by natural causes, and the like.

    The comment on "use and disuse" sounds rather Lamarckian. I wonder if it is a throw-away comment, a nod to Lamarck's work.

    Friday, 28 November 2008

    Rants and Rationality

    OK - I know this is quite old material, but I wanted to have a hack at it myself...

    Isaak here conveniently fails to mention whether by “change in a gene pool over time” he means exactly that (i.e., genetic variation, which is often called “micro-evolution”), or whether he means “macro-evolution”—which is something entirely different
    (http://www.trueorigin.org/isakrbtl.asp#observe)

    Isaak (http://www.talkorigins.org/faqs/faq-misconceptions.html) does indeed mean exactly that. The macro/micro dichotomy is a false one - little changes lead, over time, to large changes. While it can be useful to talk of micro- or macro- evolution to differentiate between the small changes seen in a population and the accumulation of those changes causing speciation, it does not mean that they are different concepts. Is Mr Wallace wanting to see two different theories to account for what he sees as two different levels of change? That would be rather like asking for a different version of the atomic theory to account for the behaviour of water and ice... or indeed, the behaviour of something light, like hydrogen and something heavy, such as uranium.

    I do, indeed, appreciate that it may be difficult to visualise that something that appears to be a set of discrete codings could ever produce something that is different to the initial available possibilities. However, as has been demonstrated with the decrease in the number of chromosomes in the human genome (24 down to 23), and the change of a bacterium to being able to consume nylon, such 'new information' can and does appear.