THE RANDOMNESS OF EVOLUTION.

This is a second entry of IS EVOLUTION TRUE. The first entry can be found here.

There is a misconception that most people who are either ignorant of evolution or just want to sully its name propagate. They insist that evolution is a random process. This misconception has gained traction by fact that any rational person understands that any random process, by virtue of being random, cannot create complexity. And here I use complexity very loosely, to mean ordered organization.

To illustrate this, I produced a set of 100 random numbers in Excel® 2013 and generated the scatter plot below. From the trend line it is clear to see that there is no correlation between the set of random numbers that I generated. This statistic agrees that complexity cannot be generated randomly (there is no apparent trend in the graph). That is, chance alone is powerless to produce the complexity of life that we observe.

Screenshot (105)
each data point was randomly generated. the lack of a trend shows randomness cannot generate complexity.

However, holding that chance has no role in evolution would be wrong. Evolution depends entirely on variations within a population. The origin of all variation is mutation. Mutation occurs randomly. So the role of chance in evolution is the generation of mutations.

Once these mutations have been generated, it is the role of Natural selection to come and pick the mutations that are desirable. You can liken this with the making of tea. During the processing of the tea leaves, the leaves are ground into powder.

The machine that grinds the tea leaves generates powdered leaves of different sizes. The different sizes are generated at random. So we can consider the grinder as the source of variations (mutations). When the processed tea leaves are added to hot water to make tea, the water naturally darkens. Before the tea can be consumed, the larger particles of the tea leaves have to be removed. This is usually done via sieving. The role of the sieve is to trap the larger particles and let through the smaller, finer particles. The sieve in this case is Natural Selection. It selects the particles that go through and those that are trapped.

From the above allegory, we can see that, in principle, given any substance that can be separated into fine and larger particles, the sieve can be used to distinguish the fine particles from the coarse ones.

By induction, it is clear that the sieving process is not random. In other words, Natural Selection is not random. Given a set of different populations, with well-defined variations in response to a given selective pressure, it is possible to deduce the direction in which the population will shift. In other words we can tell how the population will be organised. This does not mean that evolution has a mind. If the selection pressure changes, then the population will probably shift in another direction. Therefore Natural Selection depends on the selection pressure.

The first experiment I ever did was on evolution. I did not believe that variation occurred naturally in a population. My belief then was that organisms learnt what they needed to do so as to survive. So to test my hypothesis I bought 3 different sets of antibiotics. I cultured E.coli in broth having these drugs. I will not tell you the entire procedure I used, it took 3 weeks repeating the same experiments to convince myself.

In my experiments, I introduced antibiotics that acted as the selection pressure. The E.coli samples that I used came from the same population. During the course of the experiments, I was able to isolate 3 E.coli sub-populations that were able to grow in different concentrations of the three antibiotics.

However, when I introduced E.coli that could grow in the antibiotic A into broth containing antibiotic B, growth did not occur. The same applied when I interchanged the bacterial population with the antibiotic they were selected from.

It became clear to me that:

  • Variations occur naturally.
  • Natural Selection is not conscious of what will happen next.
  • Selection is not random.

From the same population, I was able to isolate 3 sub-populations that were resistant to 3 different antibiotics. The occurrence of these variations, as I have said above, occurs at random.

Natural Selection does not have a goal in mind. However, life is so intricate that design seems apparent. With design comes the conviction that the end product as always been known. But from what my experiments illustrated is the complete opposite. If Natural Selection had a goal in mind to enable organisms survive, then from antibiotic A I should have gotten individuals that could survive in both antibiotic B and C but that did not occur. Holding the same argument as true, if Natural Selection was random, from any of my isolates, I should have been able to find individuals that survive in the other two antibiotics as well.

Another way to show that selection is not a random process is tied to the rate of selection. The rate of selection depends on the strength of the selection pressure. If the selection pressure is very strong, selection occurs rapidly. This positive correlation in fact is an increase in complexity (from my definition of complexity).

There is a counter intuitive thought here, by selection occurring rapidly, it means therefore that the death rate is really high. An example is when I introduced the antibiotics in my experiments above, given that most bacteria were not resistant to it, that selection pressure was so high that majority of my E.coli were killed. But once the selection pressure was no longer in play (all E.coli could grow in the antibiotic) then the E.coli are said to be fit to live in that environment.

So when a new selection pressure is introduced, fitness falls. It therefore follows that, a low fitness means stronger selection. Consider the following graphs when the fitness are 1, 0.9 and 0.5.

Screenshot (106).png
fitness of 0.5 (top right), 0.9 (top left) and fitness of 1 is the top red line in the combined graph (below)

As the fitness reduces, the rate at which the allelic frequency reduce increases. An allele in simple terms is a gene. Since genes cannot die it means that the organism with these genes are the ones that are dying. Therefore the fall in the allelic frequency over generations is a reflection of the death rate. This correlation shows that the belief that evolution is random is simply not true.

I have tried to be as casual as possible. So as to reach a larger audience. Please don’t feel shy to share this infromation and most importantly this site. The graphs below were generated using AlleleA1, you can get it here.

As always thanks for visiting and reading.

Advertisements

2 thoughts on “THE RANDOMNESS OF EVOLUTION.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s