04
Dec
09

A blast from the past

I found this rather old post which was, strangely enough, randomly associated with one of my blog posts. I have a bit of a long response to it, so I’ll be kind and post it here. Feel free to read the blog post, then my comments.

But, I deliberately left out “macroevolution,” or the evolution of different species from one another. It’s quite a bit harder to discuss scientifically, in my opinion, because it is limited to analysis of historical events.

Interesting to discuss it this way; I only use the terms “microevolution” and “macroevolution” to describe such concepts to the lay person. It is, frankly, not difficult at all to discuss macroevolution, because it is happening right now, all over the world, in any species with distinctive and isolated populations. All you need to do is look. Ring species make wonderful examples, but there are others. So to say it is limited ONLY to historical analysis is to indicate ignorance of modern research.

This individual then puts up the DNA sequence as “code” falsehood… Again, the sequence IS NOT THE CODE. The term “DNA code” is reserved for the sequences which are templates which produce proteins. Not all of them do, the whole thing is not code, moving along. I understand this subtlety may elude many people, but it is significant. The DNA strands are not code, the “code” is the sequence of RNA which results in a specific protein sequence.

The notion that mutations can be beneficial, dangerous, or irrelevant misses the point that a mutation can be both beneficial AND dangerous (sickle cell trait and Plasmodium).

The insertion of teleology into evolution indicates, once again, ignoring the research which indicates identical conditions and circumstances do not result in the same mutations or even evolutionary outcomes in separate populations. Sorry, but evolution is not teleological, it follows selective pressures, founder effects (sample bias), and genetic drift (also an example of sample bias), as well as a few other mechanisms like selective migration and population death due to regional destruction (read: “subspecies wiped out by a volcano or other major natural disaster”).

While this individual does seem to be genuinely educated in evolutionary biology, the way he or she is explaining these matters is quite poor, and seems mostly informed by 1970s evolutionary biology. It needs updating.

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4 Responses to “A blast from the past”


  1. 1 Pliny-the-in-Between
    December 4, 2009 at 1:46 pm

    I hate the terms micro and macro evolution and try to never use them at all with people untrained in biology. It creates this notion in people’s mind that the processes are different rather than one being often more of an accumulation of the other over time (simplified explanation of course)

    hate to add another metaphor to the mix but it’s sort of like glaciers and icebergs. One get’s really bored watching glaciers trying to perceive motion. You can see the icebergs floating around so you know something’s moving, but it is the fortunate person indeed (assuming you aren’t too close) who actually sees one calf off the face of a glacier.

    The fossil record is able to be looked at in and edited and fast forward mode so you can see all the changes that really moved too slowly for our short attention spans. Most people aren’t willing to study theses processes in enough detail to see that they are still very much in motion.

  2. 2 jaredcormier
    December 4, 2009 at 2:31 pm

    Well, it’s not only the attention spans, but also our lifespans. We don’t live long enough to make repeated observations of the same populations over periods of time long enough to notice speciation. I would, however, like to point out that we do have wonderful examples of it going on, which we can use. I do not know why these brilliantly illustrated examples are not used:
    Ensatina salamanders are absolutely gorgeous in coloration, which is, precisely, the traits being measured along with snout-vent-length (SVL) and gene satellites.
    Larus gulls are also a decent example, even though the relationships here are much more complex than we would assume at first glance.
    The Phylloscopus trochiloides superspecies complex forms a “closed horseshoe” around the Himalayas.
    Many other examples do exist, but these are the most commonly used illustrations of “macroevolution” happening right now.

    The group of snakes I worked with and read about tremendously, the Agkistrodon genus has the A. bilineatus superspecies with A. taylori as the first isolation of the parental A. bilineatus/A. taylori population which was originally separated from the A. piscivorus/A. bilineatus/A. taylori progenitor probably by the Rio Grande with subsequent separations.

    To say that we don’t have stunning examples of radiation, populational isolation, and speciation ongoing is to make a false generalization. I linked to the Pod Kopiste lizards introduced to Pod Mrcaru only 38 years ago which are now very (this is an understatement) distinct from one another.

    These are examples of when someone was there to watch the icebergs fall off of the glacier, or in some cases, the iceberg hasn’t quite fallen off yet and in others, it’s just starting to float away…

  3. 3 Pliny-the-in-Between
    December 4, 2009 at 4:19 pm

    One of my favorites woolgathering exercises with this is the apparent shortening of the human jaw that we see in the last couple of generations – is this merely genetic drift that is being facilitated by modern dentistry or something else.

  4. 4 jaredcormier
    December 4, 2009 at 6:29 pm

    I had not heard of this; let me rephrase, I haven’t seen any publications on this yet.


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