Thankfully, the more we learn about reality, the less use we have for Platonic ideals. There exists no perfect circles in nature (so much for the perfection of pi), nor any perfect Gaussian distribution curves. Indeed, the models we typically apply to our observations are vain attempts to describe the world through Platonic ideals, but the world simply doesn't work that way. The world, instead, works through gradual deviations and intricate complications that cannot be predicted. This is where evolution comes into play. There is no ideal golden retriever, just as there is no ideal iguana and no ideal giraffe. Every animal (and human) we see is essentially an intermediate stage of evolution. Every living thing is both a descendant and potential predecessor for different species and classifications. There is no ideal, only a current incarnation.
With all that said, I turn now to my best summary of a brilliant experiment that demonstrates evolution in action. I read about this experiment in Richard Dawkins' book The Greatest Show on Earth, in which he devotes many pages to the details of the study, which itself had volumes of data. My explanation will be much more brief, as it is meant only to address a specific point: evolution is real and fascinating. Not only is it real, it has been demonstrated, in all its complexity, within a matter of a few decades. The experiment is carried out by a team lead by the bacteriologist Richard Lenski and, should you take the opportunity to delve deeper into it, will blow your mind.
The experiment began with 12 "tribes" of E. coli bacteria, taken from a single strain. The tribes were divided in half, with 6 of the tribes made up of cells that contain the Ara+ gene and 6 that contain the Ara- gene. The implications of this division were for later testing, as Ara+ bacteria change color when a certain chemical dye is applied to them, allowing a comparative contrast when pitted in competition against a different population of bacteria. Another cool thing about bacteria is that they can be effectively frozen for any amount of time and later thawed out with no change in their behavior. This, too, will be used to track the progress and effectiveness of the bacteria as they are allowed to evolve, as well as check the accuracy of the experiment. Each tribe was housed in a flask that contained a specific amount of glucose, the primary E. coli food source, among other substances.
The daily procedures of this experiment were simple: each day (many times a day), the bacteria was allowed to reproduce until it has exhausted its food source, then exactly 1/10th of the fluid in each flask was taken and transferred to a new flask that had the exact contents as the one before it. There, the bacteria reproduced again to its maximum potential. Every day for years and years this was repeated, to the following results: from generation to generation, the bacteria in each tribe gradually "learned" how to take advantage of their glucose food source with more efficiency. This means that at the end of each run, given the same amount of food, the population of each tribe increased. Not only that, the size of each E. coli cell also increased. Now, the changes were not uniform across the board; each tribe advanced at a different rate, using its own unique methods of adapting to the limited supply. Now, when I say "learned," I don't mean to apply the notion of shared intelligence. Obviously, bacteria are only single-celled organisms with no brain, so the improvement that we are observing is in that of their combined improvement to collectively take advantage of a limited food source.
One thing about evolution that is worth pointing out at this stage in the reveal is that certain features usually coincide with other features. With the bacteria, we saw that increased efficiency also lead to increased body size. Logically, one might assume that a small body would be more efficient in increasing population with a limited food source, but we're not discussing Intelligent Design here, obviously.
As thousands of generations passed through this experiment, it was possible to pit the current generations of bacteria against the older generations. Simply, an old generation was thawed out and placed in the same flask as a current generation. Through the use of dye, it was possible to see one generation overtaking the other by reproducing to a greater extent within the same area and the same food source. As might be expected, given a limited supply of food, the bacteria could only become so efficient to a point where it was no longer necessary to improve. While never achieving a true plateau, by generation 20,000, the population growth of each tribe had tamed considerably. At this point, a casual observer would probably turn around and say, "Good show," but we're not finished yet.
So far, what this experiment has done is demonstrate intraspecies improvements. These may be acceptable for the common evolution-doubter, as they are amusing findings but ultimately tame. What one really wants to see, when speaking in terms of impressive evolution, is evidence that one organism can somehow become something else. Obviously, we're not looking for fishes to be swimming in the broth (and if you are, you don't understand evolution), but we are looking for something that shows us what domesticated dog breeding cannot.
Enter generation 33,000 (or so). When measuring the population of one particular tribe, one of Lenksi's students found something peculiar. The population of bacteria had shot up - skyrocketed - quickly over the course of just a (relatively) few generations. Now, having mentioned that the populations in each of the tribes had all but evened out, you would think that there was a possible error or miscalculation. This is where the frozen specimen came in handy for fact checking. The findings were valid, though, and all that was left to do was find an explanation. As mentioned previously, glucose was not the only substance in each flask, but it was the only one that E. coli considered as a food source. Well, thanks to evolution, not anymore.
Through constant reproduction, evolution had granted the bacteria of that tribe the ability to take advantage of a previously untapped food source that had existed all along. This is evidence of a species of organism suddenly developing a brand new, unique ability. But, it's not as sudden as you think. We have to ask, first, why only one tribe out of 12 advanced to this point. Recall, if you will, my statement about certain mutations bringing about multiple changes. Let's think about it the other way around, with the changes all complimenting each other to allow new abilities. Every tribe eventually, at its own pace, learned to take advantage of its limited glucose food source, likely through simple mutations. However, in order to metabolize an entirely different food source, a bacteria must undergo several other mutations. Not only "several" mutations, but the right mutations at that. It is then understandable that only one out of 12 tribes obtained this ability.
So much for "irreducible complexity." While several mutations rely on each other, it is possible to catch them acting together within the same organism if you give it enough time to evolve. And, this is not to say that metabolizing a different substance than glucose is a bacteria's only hope for survival. The randomness of evolution allows an organism to take whatever direction that luck and survival allow it. Given enough generations, we would no doubt be impressed by the 12 different ways in which each tribe adapted and improved.
The coolest thing about this experiment is that it only started in 1988. Here we are, 22 years later, with evolution happening right before our eyes. Imagine this process playing out on a scale of 4.6 billion years. This, along with all the other evidence we have, speaks quite loudly. To bring it back to my original point, it is clear, now, that there is no perfect ideal... there is only an ongoing transition. That is really what everything in life is; an intermediate between where we were and where we are going. Let's keep evolving. Never stay the same.
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