scigirl

I kept thinking about this repeated claim by You Betcha today at work (aren't you excited I was thinking of you? )
This is true. Much of the evidence for evolution is similarities. The other evidence is the mechanisms for change (such as random mutations, gene duplications, etc). Similarity alone is not enough to conclusively prove that descent with modification DID occur. Like you said, maybe God just made some things the same and some things different. And the similarities we see as "evidence" of evolution are just a big coincidence.

I though about this when I was reading my "Blood Cell Morphology" book. It suddenly occurred to me that cell development provides a great analogy for evolution. The first chapter of this book describes how all blood cells arise from a progenitor, or stem cell.

Here's a picture from <a href="http://www.vghtpe.gov.tw/~hema/hematopoitic%20cell%20differentiation/hematopoiesis.htm" target="_blank">this web site</a>:



If you look at the third column from the left, you will see the neutrophil story. <a href="http://www.hematologica.pl/Stary/English/Granulopoiesis/77e.htm" target="_blank">This site</a> shows the different stages of neutrophils even better. Go ahead, take a look. Aren't they awesome cells? I have spent much of my masters thesis working on these amazing cells which are important in fending off bacterial and fungal infections.

The order of development of a neutrophil (also called a lineage):
myeloblast (from bone marrow stem cell)--&gt; promyelocyte --&gt; neutrophilc myelocyte --&gt; metamyelocyte --&gt; band cell --&gt; segmented cell (the "mature" neutrophil).

The first few steps of neutrophil development take place in the bone marrow, and the last stage can take place in either the marrow or the bloodstream. We will call this process differentiation. And although no one disputes differentiation (not even YECs I think!), let's call it a "theory" for this discussion.

Now, let's say that you are a medical technician, and you don't believe in the theory of differentiation. Instead, you believe that all of the types of neutrophils were created separately, all at once, by a process unobservable to clinicians. Of course, people would think you were silly (since unlike macroevolution, you can actually watch the whole maturation process in a couple of days). But suppose you hold that belief. In order to do this, you would have some problems, based on the facts that are presented to you in hematology class.

Your first problem as a "separate neutrophil creationist" would be explaining why it's difficult to distinguish between all of the cell types. It is often difficult to tell the difference between a band cell and a fully mature neutrophil, or between a myeloblast and a promyelocyte. This difficulty is explained wonderfully by the 'theory' of differentiation. According to the theory, small changes in each progenitor cell occur to create the next cell, and so on. For instance, to create a myelocyte from a promyelocyte, granules have to be formed. These granules do not appear in earlier lineages, and appear in all the later lineages. The neutrophil creationist would be at a loss to explain this fact if the neutrophil types were all created separately. True, it could be a coincidence. A "differentialist" could ask the creationist--"Why don't you ever see myeloblasts with a banded nucleus if they were not created in a lineage?" And the creationist could only reply, "I don't know, that's just how they were made."

See, the theory of differentiation not only explains that there are similarities and differences, it explains exactly why each similarity and difference occurs! The development of granules, the lobing of the nuclei, the re-organization of the cytoplasm--all make sense using the theory of differentiation. Granule formation is correlated with increased protein synthesis and decrease in cell size. The morphological differences that med techs see (such as the cells turning from blue to red as they develop, with a Wright-Geisma stain), is perfectly explained by the differentiation hypothesis: The stain is actually showing you what types of granules are being produced. Maturation of the myelocytic series of cells is characterized by the development of dark and blue-staining primary granules which are later replaced by secondary granules that take up red dye. A differentiationist does not need to explain why there is a perfect correlation between the transition from blue to red, the appearance of secondary granules, and the age of the neutrophil. A creationist has a lot of coincidences to explain!

A neutrophil creationist could say, "The neutrophil creator made them all, so you expect some similarities." This explanation however still does not explain why the similarities just so happen to correlate with the differentiation theory. The creationist will also say, "he neutrophil kinds will also have differences," but will be unable to explain why the specific differences exist that are also nicely accounted for by differentiation theory. In other words, the creationist explanation is not really an explanation at all.

This is an analogy for the problem of classification. Evolution predicts that it is difficult to categorize all animals into discrete kinds, YEC predicts that it should be much easier. Why are so many skulls are found which have both chimp and human characteristics? The fact that it is very difficult to classify everything into one 'kind' or another is a big proof for evolution!

It is also interesting that you don't see abrupt appearances and disappearances of a structure along an evolutionary lineage. Instead, you see reasonably smooth transitions, which correlate with age of the fossil. If the neutrophil creationist did indeed discover a bunch of myeloblasts with banded nuclei, then they would have some credibility. Likewise, a YEC that discovers a fossil of a modern human which pre-dates the chimp-like ancestors we have found--this would be good proof against evolution. And to my knowledge, these types of fossils are rarely found.

Here are some statements you made which illustrate how your arguments parallel that of the neutrophil creationist:
The second problem for the neutrophil creationst will be (which is similar to the first problem), why do there seem to be transitions between the cell types? Of course differentiation theory predicts transitions. When a differentialist shows him a progression of cells from myeloblast to neutrophil, his response may be, "Where are the transitional cells between a promyelocyte and a myelocyte?" He will insist upon seeing a neutrophil with a rounded nucleus, then a neutrophil with an oval nucleus. The differentialist will produce photos of these neutrophils. Then the creationist might demand a nucleus between oval and round, and so on. After the differentialist produces nearly every type of nuclear transition, the creationist still claims, "You can't prove that one came from the other. I still maintain they were all created separately."
Rather than focus on the (false) claim that there are "no transitional fossils," let me ask you this? Why does it look like there are transitions at all? Note that transitions are not just similarities. If evolution is false, and YEC is true, why do transitional patterns of things like wings, brains, etc, even exist in nature? To me, the fact that it even looks like transitions happened (even if you can't find every single fossil, or oblong nucleated cell) is again, evidence for evolution.

A third problem for our creationist will be mRNA expression. Now, keep in mind that the theory of differentiation was developed by scientists before the discovery of RNA. For the record (in case your background in genetics is not as good as mine ), messenger, or mRNA is the part of the DNA that gets expressed and used. It is the message between DNA and protein, and thus the way that DNA can carry out its orders. So, scientists had this differentiation theory, and they proposed a hypothetical lineage for these cells. Now, if their pattern is correct, then you should expect to see mRNA levels go up and down in a characteristic pattern with this hypothetical lineage. Why is this so important? Because mRNA levels dictate differentiation. So they better correlate with it, right? For instance, if you measured expression levels of NADPH Oxidase (a protein that neutrophils need to kill bacteria), you should not see the levels go up and down randomly if you measure their levels in the lineages. As it turns out, both specific messages, and general mRNA expression levels, correlate with the lineages. They also correlate with the function of the lineages. Since mature neutrophils are incapable of cell division, you would expect global mRNA levels to decrease with differentiation. And you do. Keep in mind that the proposed lineage order came about before the genetic data. A neutrophil creationist once again will have to believe this is a huge coincidence, or maybe even accuse the scientists of making up the data.
This is another parallel for evolution. When evolutionary trees were first proposed, scientists didn't even know what DNA was. (Darwin's theory did predict the discovery of genes though, unlike the first chapter of Genesis!) So possible evolutionary trees were constructed based on organism similarities and differences. A century later, when the genomes of organisms started to become sequenced, the data overwhelmingly supported the original evolutionary trees. This consistency is very important, because like the mRNA above, the genomes dictateevolution. Again, creationists will just say it's a coincidence, but they fail to offer any explanation as to why the similarities between evolutionary trees, and between genomic sequences, correlate so well. The evolutionary answer is clear: since changes in the genome cause evolution, they better correlate, and they do!

The fourth problem that a neutrophil creationist has is one of placement: How to explain why we only find certain cell types either in the marrow or the bloodstream, and these cell types just happen to correspond to the differentiation theory. I mentioned earlier that you should not see a metamyelocyte, or any earlier-stage cell, in the bloodstream. If you do, there is a problem going on, such as cancer. Of course differentiation theory explains this very well: The stem cells which create neutrophils originate in the bone marrow. The process is highly regulated, and at either the band cell or the mature cell stage, the cells are released into the bloodstream. Now, if you start seeing earlier cells in the bloodstream, the differentiation hypothesis would predict a dysfunction in regulation. And that is exactly what you do find: in myelocytic hyperplasia, you will find metamyelocytes in the blood. Hyperplasia is just a fancy name for 'too many cells,' and often indicates a bone cell cancer. The creationist explanation would be something like, "Some type of event, which you can't observe in the body, creates all the neutrophil types that way, and in those places. This event is outside of the realm of science so you can't measure it."

This dilemma is similar to the YEC interpretation of the fossil record. The fossil record clearly shows progressions of animals with time. You do not find modern mammals in the old strata, you do not find prehistoric dinosaurs in the later strata. Period. YEC predicts the opposite-that all of the fossils should be mixed together. However, creationists will make up some strange stories about how the flood somehow magically sorted the fossils (amazingly enough, sorted in such a way to support evolutionary theory) instead of just accepting evolutionary theory as an explanation.
The fifth problem the creationist med tech will have is the rejection of not just neutrophil differentiation, but differentiation of every cell type in the body. Differentiation has been independently characterized in many cell types, and in each case, the pattern is the same: There is a stem cell which specializes down a given pathway by a combination of cell division and cell change. Intermediates between the final cell and the stem cell are nearly always found, and these correlate with what biologists know about where the cell started from, and where it needs to end up in the body. The mechanisms which regulate and govern differentiation are still not completely understood, but it appears that they are common, and similar for all life forms. The med tech may be able to get away with dismissing neutrophil differentiation, but what about lymphocyte differentiation, and all of the other types? See, the med tech now has to believe in millions of special creations of many cell types, whose characteristics once again happen to correlate with differentiation theory anyway. Deep down, he may still believe that all of the cell kinds were created separately. But accepting the descriptions, the functions, and the relationships that are provided by the differentiation theory are just so useful in predicting the cells, he will have no choice but to use them anyway.

Similar to evolution: Data for descent with modification has been found for nearly every creature that we observe. And while it is true that we are still figuring out the exact mechanisms, these mechanisms seem to be similar in bacteria and humans. No special or magical event seems to be necessary to cause evolution (or differentiation): just lots of combinations of regular old genetic events. And again, a YEC rejects so much evidence, which is found over and over, in various lines of work such as geology, physics, and genetics. The amount of coincidences they have to reject in order to reject evolution is astounding.

You see, You Betcha, people who don't accept evolutionary relationships are like that medical technician. You can claim that the human and ape skulls shown in Daggah's post here on <a href="http://ii-f.ws/ubb/ultimatebb.php?ubb=get_topic&f=3&t=001596&p=5" target="_blank">page 5</a> are just coincidentally similar in a progressive order, but if you really want to understand why chimps have a smaller brain, and no capability of speech like we do, you will just have to accept that God made them in the same order that evolutionary biologists put them in. If you want to understand why a virus affects certain animals, you will have to believe the molecular biologist's data which show how genetic similarities and differences, which correlate well with evolutionary trees, simultaneously explain disease prevalences. If you want to believe that the flood sorted the fossils, you'll have to use the paleontologist's ordering system anyway since it works so bloody well to predict the fossils we will find in an undiscovered area.

You can claim all you want that evolution didn't occur. But sooner or later, you will have to accept that it did occur if you want to actually explain the data in a coherent, consistent manner.

scigirl

Edited to fix the corrupt text when I copied from word. Stupid microsoft!

[ January 03, 2002: Message edited by: scigirl ]</p>

Coragyps

<img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" />

Viti

Wow...good job...common enough terms even for a scientifically retarded girl like me

MrDarwin

Correction: similarity may or may not mean relatedness. Phylogenetic relationship deduced from similarity is a scientific hypothesis, subject to testing and potential falsification like any other hypothesis.

[ January 03, 2002: Message edited by: MrDarwin ]</p>

Bubba

Nice Work, Scigirl.

Bubba

Kaina

It will likely have no impact on the intended target, but it sure impresses me! Good work.

Kaina

Dr Rick

Well done, scigirl.

babelfish

Scigirl,

Easy enough even for fans of Kent Hovind to understand. Right on! You go girl!

Jobar

Scigirl, you should submit that for publication somewhere. Try Skeptical Inquirer, or any good biology-education journal. Excellent work, and IMO quite original! <img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" />

Daggah

Scigirl,

Since the number of posts per page in a thread has been reduced from 25 to 15, my post about the skulls can now be found on page 8, <a href="http://ii-f.ws/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001596&p=8" target="_blank">here</a>. Just letting you know.

I'm honored that I was mentioned in your post! <img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" />