THE BASIS OF DIVERSITY

EVOLUTION – THE CYCLE OF LIFE OVER TIME

INTRODUCTION

This essay was motivated by my desire to establish a basis for ethics – the nature of humans should inform ethics - and by my recent awareness of a Texas School board that has successfully denied students the opportunity to study evolution in high school science classes.

I like to argue from essentials. Changing people's minds by having them accept your opinion is a meaningless interaction for both parties. Much better to get to the essentials upon which your opinions are based, so that listeners or readers can use the facts to reason and draw their own conclusions. This requires that you define the basic identities of the existents used in your argument. You may have noticed in previous blogs, and will continue to see in future essays, that at some point in the writing, I define a human being as a “rational animal.” I believe this fact must be the basis of ethics – morality comes from truth and truth comes from understanding the nature of the entities involved. I have argued that relationships, laws, government, etc. should be based on that special capacity, reason, because it is the essence of our nature. My belief that reason should be the basis of ethics is founded in an even more basic idea. The nature of life, the reason for the incredible diversity of life, and the source of the unique human survival mechanism of reason is evolution. Such a simple word, but what an incredible process.

I am in awe of the biological process that led to this unique human ability, so, I thought it would be a good idea to write an essay about the process of evolution and it's engine, natural selection. The ability to reason exists because an even more incredible process led to it. As soon as chemicals came together on earth in a way that they could self-generate copies of themselves, the universe changed – it required a solvent, water; the building blocks of carbon and hydrogen; and some easily reactive elements like oxygen and nitrogen. You think the Big Bang is cool, you think Black Holes are the bee's knees – evolution of species through natural selection is even more cool because you can understand it without knowing physics or calculus. I hope at the end of this essay you will agree that Darwin and his colleagues are the modern equivalent of Galileo.

MY PERSONAL JOURNEY

The reasons that people do not accept evolution as fact are numerous, and I think this doubt is reasonable. If my parents had warned me about the godless ideas of evolution, I would have found the whole discussion comical, based on how it was presented to me.

Darwin's ideas were introduced to me as a sophomore at Cardinal Spellman High School. It seemed like interesting and curious nonsense. The emphasis was not on chemistry or genetics because there was not enough time to cover those basic elements first. Instead, we were asked to consider the idea that man descended from apes with little or no discussion of DNA, reproduction, or protein synthesis. I thought Darwin's finches made a cute story that could be explained many different ways. I agreed with creationists, that the archaeological discoveries of pre-human hominids didn't necessarily support evolutionary theory. It could be that totally different animals, similar to humans, existed and became extinct.

I studied biology and genetics in college and began to reconsider my position. Then in grad school I read extensively on the philosophy of science and the link between biochemistry and evolution. I learned that the proof of evolutionary theory, required way more knowledge than I got in high school or college. It required knowledge of the validity of inductive vs. deductive reasoning, and a much deeper understanding of reproductive biology. I began to accept it and years later I was vindicated by discoveries in genetics and molecular biology.

HISTORY

The idea that living species might change form through successive reproductive generations based on changes in their environment has been around, off and on, since before Socrates. In the 5^th and 4^th centuries BC, the Greek philosopher, Anaximander, and the Chinese Taoist philosopher, Chuang Tze, both speculated that species they saw in their time, might have developed from older forms. In the 4^th century AD, the Greek bishop, Augustine of Hippo, cautioned that the Genesis story of creation should not be taken literally because it appeared that life forms had transformed over time. Even Thomas Aquinas said in the 13^th century, that scripture should not be taken literally when the facts of natural science disputed it.

In the 19^th century, an Augustinian friar would find an underlying truth about reproductive biology without even knowing it. Gregor Mendel used discernible characteristics in pea plants to show regular and repeatable patterns of inheritance. He didn't know it, but his data proved that the structural basis of inheritance, the chromosomes, came in pairs, one from each parent In the 20^th century the independent discovery of these same patterns led to the modern science of genetics.

In the mid-1800's Charles Darwin and Alfred Russell Wallace, independently arrived at the conclusion that life forms changed over long periods of time based on the interaction between reproductive variation and environment, and that this process could account for the incredible diversity of species, both alive and extinct. In 1953, Watson and Crick published their discovery of the structure of the DNA molecule. Later, the first draft results of the Human Genome Project were released in 2000. We can now map the genetic structure of living things. In 2009 the Vatican announced that Darwin's theory was not in conflict with Catholic dogma and was in fact the culmination of the thoughts of St. Augustine and St. Thomas Aquinas.

The truth is that with the chemistry of life totally revealed, there is no longer any question. Life began with a simple chemical replication of molecules . This replication is the first definition of life. Life is self-generated and self-sustained action that can make copies of itself. Once the replication process exists, there is an incredible engine for diversity in life forms based on adaptation to different and changing environments. Not within an individual, but within a reproducing population of living organisms.

The truth of evolution is not revealed in a study of evolution. Like many ideas in science, understanding requires knowledge of the underlying principles that direct the process. Those ideas are biochemistry, genetics and natural selection.

GENETICS AND BIOCHEMISTRY

Each living cell has a number of pairs of chromosomes, 23 pairs in humans. The backbone of each chromosome is a long molecular chain called DNA. Each cell's set of chromosomes is the complete library of the organism. The DNA strand is surrounded by proteins that expose or hide parts of the strand along its length so that a cell doesn't make nerve tissue if it's located in a muscle, etc.

To think about a DNA molecule, picture a flexible ladder. You grab one end and a friend grabs the other and you twist in opposite spin directions. The uprights are attracted because four chemicals, called base pairs, make up the rungs of the ladder and fit together spatially and magnetically. Adenine (A) matches up with Thymine (T), and Guanine (G) matches up with Cytosine (c). The strand will then twist on the twists based on the positive and negative fields on the outer surface – it twists upon twists in a predictable way because of attraction like a magnet.

Along the ladder uprights, the order of the chemicals – A, T, G, and C - determine everything that you are because they determine the synthesis of proteins in your body. The only exception in humans is the content of your thinking, everything else is determined by the order of the base pairs.

AACTCGGATCA makes one protein – ATCGCGGTAAGAGACATA makes another. If you have studied computer theory you should not be surprised that all of biology is based on a pair of pairs – binary upon binary.

When it's time to go to work, the twists unwind and the uprights of the ladder separate through the influence of a chemical called an enzyme. Each half of the strand has now exposed it's side of the base pair (A, T, G, and C) to connect with something else. If the DNA is getting ready for the cell to reproduce (split into two) each strand attracts the molecules necessary to make it whole again in the same sequence as the original. Once everything is doubled, the chromosomes and half the cell contents migrate to the sides and split into two new cells. Now you have two skin, muscle, or nerve cells.

If they are reproductive cells, they do what was just described, but then the re-formed and paired chromosomes separate in the male and the female (in humans 23 identical pairs or 46 chromosomes split, with 23 individuals each moving into a new split cell). Now each reproductive cell, sperm and egg for example, have half the DNA content (23 individual chromosomes in humans) so they can combine with the opposite sex cell to create a whole embryo (46 total comprised of 23 pairs). In humans it would go from 23 pairs to 46 pairs, cell separation, each back to 23 pairs, split into two sex cells of 23 singles each, and finally conception back to 23 pairs.

I have read dozens of author's descriptions of this process and never understood it. I only got it right when I sat down with a piece of paper and worked out the process visually. I did this the first time I had to teach it to a class and didn't want to look like a fool when they asked questions. It's complicated – no wonder the Baptist minister doesn't get it.

Between cycles of reproducing new cells, the DNA splits in the same way, but now gets ready to manufacture proteins – skin, bone, muscle, etc. Now the split and exposed DNA strand, with its A, T, G, and C sticking out, attracts molecules that fit and form a strand of a new molecule called RNA. This RNA has a repetitive base sequence like DNA, The RNA travels to a factory in the cell called a ribosome. In the ribosome, amino acids that fit in space and magnetism line up along the RNA strand to make proteins.

Is that amazing or what? The same set of molecules makes more cells, is the basis of reproduction and inheritance, and makes all the tissues in the organism through protein synthesis. Because this same set of molecules is responsible for all three processes, protein synthesis, cell divisions, and organism reproduction, the blueprints of protein synthesis and cell division are inherited through reproduction. What a system!!!

Yea it was an intense explanation of genetics, reproduction, and protein synthesis, but if you read through it a second time, slowly, it's understandable, though not simple. So, don't think as harshly about religious people who disagree; this is “rocket science.” Can you see why the deacon of a Baptist Church, an educated man or woman, sitting on the Austin, TX school board would want to make sure that creationism is presented along with evolution? He's wrong, but his prejudice is never going to allow him to waste the amount of time necessary to understand the chemistry of life, the basis of evolution. He/She thinks evolution has to do with archeology and human relationship with apes. Theologians in the 17^th century didn't have the mathematics or physics knowledge to follow Galileo either.

NATURAL SELECTION

Now it gets really interesting. You have the basic biochemical and genetic facts necessary to follow the evolution argument. This is the original inductive argument proposed by Darwin, Wallace, and others with some help from more recent discoveries.

Living organisms produce more offspring than could possibly be supported in the habitat they occupy. This hopefully insures that some will live to reproduce and the excess reproductive energy provides food for other organisms.

During reproduction, the chromosome pairs separate, duplicate, and then match up with the set coming from the other parent. Variation comes from the two distinct parents, but also from another mechanism. During this process there are lots of opportunities for the sequence (the order) of chemicals (remember A, T, G, and C that make proteins) to change from the original sequence in the DNA of the parents. These unexpected changes are called mutations. Mutations also occur in other ways.

Mutations may screw up the chemical and magnetic physical structure of the DNA or result in an order of A, T, G, and C that result in a lethal protein. So, most mutations are never seen because the change is so dramatic that the offspring is either not conceived or not born. Lesser mutations result in the diversity in the look and function of offspring that we can study because their proteins are slightly different. Maybe it's a difference in fur color, bill length, sexual desire, or another instinctive behavior; the possibilities are almost endless.

So, genetic diversity is a byproduct of reproduction. Some offspring will be better suited to their environment and will then be more likely to live and reproduce in the next generation. The change could be metabolic, physical appearance, or behavioral, and if it makes the organism more successful, adapted to it's environment, you get more babies. Successive generations will be just as diverse around an earlier change and just as subject to survival pressure. After many generations, a diverging strain becomes so different that it can't or simply does not mate with the original population – a new species is born.

If a species is dark with soft teeth, but the environment changes, or the population moves to exploit new habitat, and the new circumstance favors lighter color to fool predator and stronger teeth to exploit a thicker nut food source, then that part of the population that more closely approximates the requirements will be more likely to live, reproduce, and pass on their unique genetic sequence. This leads to a modified protein synthesis, that favors lighter color and stronger teeth, in a larger and larger segment of the population. It's so simple and so complex.

SUMMARY AND CONCLUSION

The scientists who possess all the knowledge of biochemistry, genetics, and reproductive and population biology are busy studying their disciplines. Most have no time or interest in appearing before a local Texas school board. The few who do, are of course not given the time and attention that is required to explain the basis of evolution.

Today we can map genetic anomalies at the molecular level over time. We can say that the changes that occurred and allowed upright posture happened at this point. We can look at the DNA in a part of the cell called a mitochondria and know that an organism that lived during a certain time became the progenitor of both apes and proto-humans. We didn't descend from apes. We descended from some more primitive and now extinct form that also gave rise to apes.

It is a common mistake to assume that evolution has a goal. It seems like evolution has been directing life toward the ultimate organism, a human being. No, we are just one of many success stories in the random lottery that tries to fit forms to their environment. While we have been evolving, so have countless other forms that fit like a glove into their own niche.

Once you take the time to study the underlying science that coalesces to form evolutionary theory, you learn that it is more amazing than you thought. Life uses it's chemical make up, the biological link to the environment, and population biology to support itself and to develop new life forms.

Some scientific theories involve subject and content that occur over long periods of time, or out of human perception in time or space. For this reason, these ideas cannot be proven like a mathematical equation. The idea of a paradigm, in part, recognizes the validity of inductive reasoning. We cannot prove this theory deductively, but the amount of inductive process applied to the theory is so overwhelming, that we accept it as the standard of inquiry. Newtonian physics developed in the same way. Einstein's theories didn't invalidate Newton, they added information to it. The historic inquiry into life's diversity and the current biochemical discoveries in the sequencing of DNA combine to give us one of the best examples of the validity of inductive reasoning.

The Human Genome Project has also put a final end to a a long standing social evil. Biologically, there are not different races of humans. Biologically, we are all the same. The idea of racism is not supported by science and the word racism is a misnomer, we are not different races. If you want to hate people, you'll have to find another basis. But, this is a topic for another essay.

Liberty does not require you to agree with all or any ideas except the prohibition on the use of force and fraud.

Now go make your loved-one a sandwich.