Posted by: zyxo | November 14, 2011

It seems like Evolution is NOT the result of Natural Selection

Yesterday I got an interesting comment on a previous post on evolution.
I thought my answer would be to elaborate for a reply, hence this reply-post.

Tias Dailey writes the following (bolds are mine):

“You wrote that in one winter, a population of birds could be affected by natural selection because the small birds die off, leaving the larger birds. The thing is, natural selection always has a narrowing effect on the variation in a population. Understand that in your scenario, large birds did in fact exist before the natural selection. So that in itself is not evolution, but only narrowing of the gene pool. So that scenario doesn’t show that evolution can occur quickly.
To show that evolution can occur quickly, you would need to show that new features can arise quickly—features that were not present before.”

In fact, Tias makes 2 statements here :

  1. Natural selection always has a narrowing effect on the variation in a population.
  2. Narrowing of the gene pool in itself is not evolution.
The first conclusion we draw from these 2 statements are purely logical : since 1)Natural selection always has a narrowing effect and 2)a narrowing effect is NOT evolution then it follows that natural selection cannot be the cause of evolution.
In the above, we assume that both statements 1) and 2) are right.  [As many will know, it is always dangerous to assume (ASS U ME)].
So when does evolution occur ?  If it is not when natural selection occurs (as a result of some sort of more severe environmental pressure) then it must occur in the opposite situation : when the environmental pressure is relaxated.  Under those circumstances inheritance / mutation / recombination can do a lot more without being naturally-selected away.  In other words: the variation in the population increases and new features (e.g. a bird that’s larger than any previously existing individual of it’s species) can see the light. Aha, we have evolution.
But let us look at Tias’ 2 initial statements.  Are they correct ?
For the first one : OK, I agree.  Natural selection does weed out the non-fit outliers and narrows the population variation.
For the second one : NOK.  Why should narrowing of the gene pool in itself not be evolution ?  By the way… What IS evolution ?
Let’s look at some definitions:
  • Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals (the free dictionary)
  • Biological evolution … is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions. (talkorigins)
  • Biological evolution is defined as descent with modification.   Biological evolution occurs at different scales. These include small-scale evolution and broad-scale evolution. Small-scale evolution, also referred to as microevolution, is the change in gene frequencies within a population of organisms changes from one generation to the next. Broad-scale evolution, also referred to as macroevolution, refers to evolution at a grander scale. It focuses on the progression of species or entire clades from a common ancestor to descendent clades over the course of numerous generations. (animals.about)
  • Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins. (Wikipedia)
So what do we see ?  “change in genetic composition”, “changes in populations…that are inheritable”, “change in gene frequencies”, “change in the heritable characteristics of biological populations”.
So what about narrowing of the gene pool ?
  • This IS change in genetic composition.
  • This IS inheritable.
  • This DOES change gene frequencies
So IMHO narrowing of the gene pool is evolution.  Evolution does not always add new features.   Losing capabilities as a result of evolution is called regressive evolution.  Examples: the european mole that start to live beneath the ground and lost its vision capabilities.
To finish let me make a comparison.  Is it necessary to walk from New York to Rio De Janeiro in order to prove you can walk ?  Nope!  If I can show you that I can walk 10 steps, you will believe I can walk.
Likewise, is it necessary to show the emergence of a totally new feature like for example wings in order to prove evolution ?  Nope! If we can show a change in genetic composition of a populations, than we have shown evolution at work.
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  1. I love how your post is logically structured, and how you distilled my statements into their logical points. I see that you disagree with my statement that narrowing is not evolution. But that is because we both have different definitions of the term “evolution.”

    You listed a few definitions that said that evolution is simply change, in whatever direction. People say this a lot, and it sounds true. After all, genetic changes are random, as well as natural selection. But remember the overall direction of evolution so far.

    Generally the trend of evolution should be “upward,” which means more genetic information to code an organism’s features. From the first bacterium to the present complex and diverse organisms, there was an upward trend. More DNA codes were added over time. Today, the general direction of evolution is downward. We see that genetic modification is very destructive to an organism.

    That was a bit off topic. My main point is this: from the first organism to today’s more complex organisms, evolution did not occur via narrowing of the gene pool. That would imply that the first organism was incredibly genetically diverse. The theory of evolution basically has two steps: genetic mutation and then natural selection. Mutation is supposed to yield new features or genes, and then natural selection narrows the gene population to exclude the non-evolved organisms.

    My main point was that in order to look for evidence that supports the overall supposed direction of evolution, you need to look at genetic modification and not natural selection. Because genetic mutations are the driving force. Natural selection can’t “add” anything.

    I look forward to your thoughts on this.

  2. Hi Tias,
    I think we do agree after all.
    Although evolution can be downward, it is indeed clear that the general trend is upward. Not only in the sense of more genes, but more generally in the sense of more levels that are added on top of eachother controlling the lower levels (like new sorts of genes that control other genes etc…). I mentioned this for instance in previous posts and

  3. Evolution And Natural Selection

    Natural selection is energy (E) temporarily constrained in a mass (m) format.

    Evolution is the sequence of processes between physical states ordained by natural selection.

    Evolution Is The Quantum Mechanics Of Natural Selection. Period.

    Dov Henis (comments from 22nd century)

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