Genetics is a relatively new term and an even newer science, but the ideas behind what genetics truly is, are ancient. The techniques early farmers and even their modern day counterparts employed of planting certain seeds in order to produce a specific crop and then continuing this process by selecting seeds from the next crop to cultivate exactly the strain they wanted, is the core of the basics of genetics. But we will not begin by focusing on the technical aspects; instead we are going to start from the beginning, and illustrate the process of how genetics evolved, showing gaps in time, and a survey of who did what and when. In a sense, this paper will be a historical journey through some of the most interesting parts of the study of genetics.
From the beginning of recorded history, the basis of how things were thought to be was from the belief of creationism: god(s) created the earth and all things upon it. With this concept there isn’t room for change or any type of evolution in thought. Things remain fairly static until we jump ahead to the year 1831 AD. This is the point at which Charles Darwin set out on board the HMS Beagle to become a science officer. The ship’s mission was to explore around the world for five years. It was during this time that Darwin started to look at extinct horse forms, but more importantly he was able to visit the Galapagos Islands. It was here at this closely grouped set of islands that Darwin would discover seemingly similar yet different species of finches. Though these islands were geographically close they were isolated enough from each other that these birds could not travel from one island to the next. Darwin noticed a visual difference in the birds by how their beak shape varied. Each bird had seemingly adapted to be able to find the types of food found on their own individual island. It wasn’t until 1836 when Darwin returned from the Galapagos that he had more then enough research regarding his theories, about what he called Natural Selection. He was wary of the reception to his findings and originally did not want to have them published until after his death. But come 1858 when Anthony Wallace was working on similar research and had enough compiled to publish his own findings; Darwin was prompted to reconsider publishing his work about Natural Selection. In the end, Darwin and Wallace jointly brought a paper to the Royal Society in 1858. The following year Darwin published “On the Origin of Species,” which became the starting point of the serious consideration and study of genetics.
During the period of time between 1856 and 1863 Gregor Mendel began doing his research on the cultivation of pea plants. In those seven years Mendel worked with over 28,000 pea plants in which he used to forge his laws of inheritance. Three years later, in 1866, Mendel published the paper "Experiments on Plant Hybridization.” When it was published none of his contemporaries understood it, and it would still be many years until people began to. It wouldn’t be until the year 1900, 35 years after its publishing, when Mendel’s work would be rediscovered. This caught the eye of other scientist’s thinking that Darwin’s and Mendel’s work needed to be looked at together. In 1942, Julian Huxley published his paper “Evolution, The Modern Synthesis,” tying together the work of Darwin and Mendel. Now the ideas of Natural Selection and genetics became fundamentally linked. This caused research into the field to really take off which helped lead up to 1952 when James Watson and Francis Crick discovered the double helix structure of DNA.
It was not until 1990 when the International Human Genome Sequencing Consortium, led in the United States by the National Human Genome Research Institute and the Department of Energy begun the Human Genome Project. According to the Human Genome Project Information web site, the project was to complete the following:
Identify all the approximately 20,000-25,000 genes in human DNA, determine the sequences of the 3 billion chemical base pairs that make up human DNA, store this information in databases, improve tools for data analysis, transfer related technologies to the private sector, and address the ethical, legal, and social issues (ELSI) that may arise from the project (www.ornl.gov).
On April 14, 2003 all of the initial goals of the Human Genome project were achieved. So all 23 pairs of chromosomes, well 22 pairs, and X and Y, have been mapped.
Discovering DNA and having mapped just about all of it out is all well and good, but where is it, and what makes this important to us? Simply put DNA is in just about every cell in every living being on Earth. One of the chief reasons that DNA is so important is that it directs protein synthesis within the cells. Proteins, in a sense, make us into what we are. According to Robert Jurmain, et al. proteins are very important like hemoglobin, a protein, in blood that serves to transport oxygen, collagen which is a critical part in every connective tissue, the enzyme lactase, still a protein, that breaks down milk sugar, and the hormone insulin, also a protein, which makes certain muscle tissues and the liver absorb sugars (48-49). DNA is so important that all new cells must get a complete and perfect copy of the original DNA, all three billion base pairs.
Now let’s delve into this further. If you were able to unwind a full strand of DNA, all three billion base pairs, it would stretch about two meters. Since there is two meters of DNA in every cell, how much DNA is in the average human body? According to Vadim Gerasimov, Ph.D there are about 60 trillion cells in the average human. So two meters of DNA per cell at 60 trillion cells is 120 trillion (1.2x1014) meters of DNA, this seems like too great a number to fathom. Changing this into kilometers we get 120 billion (1.2x1011) km of DNA; that is still quite a large number to grasp. Now let us break that concept down into something more manageable; one Astronomical Unit (AU) is about 150 million (1.5x108) km according to Eric Chaisson, so all the DNA in the average human would be about 800 AUs, or about 20 times the distance Pluto is from the sun.
With the knowledge that DNA has to duplicate properly, and that there are three billion base pairs that need to successfully do this, odds are that there are bound to be mistakes during both the process of mitosis and meiosis. According to Amanda Ewart Toland, PhD:
Everyone acquires some changes to their DNA during the course of their lives. These changes occur in a number of ways. Sometimes there are simple copying errors that are introduced when DNA replicates itself. (Every time a cell divides, all of its DNA is duplicated so that the each of the two resulting cells have a full set of DNA.) Other changes are introduced as a result of DNA damage through environmental agents including sunlight, cigarette smoke, and radiation. Our cells have built in mechanisms that catch and repair most of the changes that occur during DNA replication or from environmental damage (Ewart Toland).
Though our cells have mechanisms in place to spell check the DNA, if this process does not check the DNA correctly, or the mechanism fails to work at all, then the new cell will continue to contain a mutation. There are many different types of mutations, from point mutations, which would turn the line “The fat cat ate the wee rat,” into “The fat hat ate the wee rat,” frame shift mutations which turn the original line into “The fat caa tet hew eer at,” deletion mutations which would create “The fat ate the wee rat,” insertion mutations creating ” The fat cat xlw ate the wee rat,” and inversion mutations “The fat tar eew eht eta tac” (Ewart Toland). Mutations in the gametes can lead to mutations in the embryo. These mutations in the embryo and even in the parent can be disastrous, according to the March of Dimes website, “factors known to cause first-trimester miscarriages, the most common is a chromosomal abnormality in the fetus…Most chromosomal abnormalities result from a faulty egg or sperm cell.” This makes it sound like all genetic mutations are bad. For the most part they are, but even the mutation that leads to sickle cell anemia has some good benefits, though it is at times lethal. According to pbs.org, “Doctors noticed that patients who had sickle cell anemia, a serious hereditary blood disease, were more likely to survive malaria, a disease which kills some 1.2 million people every year.”
Though the science of genetics is new, it has progressed quite a long way in a very short amount of time. Yet it still continues to have a long way to go and much more to discover and learn. I personally find this topic very interesting, the time scales, the shear numbers, and the statistics of it all. I can’t wait to see where research in this field goes next, what diseases will be able to cured, what new genetic problems might arise that could be harmful and possibly even have the capacity to kill us, and even if man kind has the potential to evolve our own selves using science.
Chaisson, Eric, and Steve McMillan. Astronomy: A Beginner’s Guide to the Universe.Upper Saddle River, New Jersey: Pearson Education Inc., 2004
Ewart Toland, Amanda. “Genetics 101: DNA Mutations.” Genetic Health 3 Jan. 2001. 29 Aug. 2005.
Gerasimov, Vadim. “Information Processing in Human Body.” 2000. 29 Aug. 2005
Human Genome Project Information. 27 Oct. 2004. U.S. Department of Energy Office of Science, Office of Biological and Environmental Research, Human Genome Program. 27 Aug. 2005.
Jurmain, Robert, Lynn Kilgore, Wenda Trevathan, and Harry Nelson, Essentials of Physical Anthropology. 5th Ed. Belmont, CA: Wadsworth/Thomson Learning. 2004
“Miscarriage.” March of Dimes. Aug. 2004. 29 Aug. 2005.
“A Mutation Story” pbs.org. 2001. 29 Aug. 2005.