G e n e tics
Genetics: Past, Present, and Future
Image courtesy of Leighton Pritchard. Retrieved from http://www.flickr.com/photos/widdowquinn/7519465880/in/pool-1391687@N20/. (Accessed 8 May 2013)
by MacKenzie Foley
Introduction Genetics is the study of heredity and the variation of inherited elements known as genes. Although scientists have long known that an offspring’s traits come from its parents, the findings of Darwin and Mendel have really allowed scientists to begin to understand how and why genetic variation occurs. With advances in scientific research and informatics, genetics has become increasingly significant in revealing the causes of diseases and the differences among individuals and species.
Past For centuries, western religion contributed to the widespread acceptance of the theory of “creationism,” which refers to the literal interpretation of the Bible in which God created the Earth and all modern, immutable species around the year 4000 B.C.E. Advances in geology and observations of incremental changes of species in the fossil record over time led to skepticism that eventually brought forth the development of the theories that make up the foundation of selection theory. The first major theory of genetics was hypothesized by Hippocrates in fifth century B.C.E. Hippocrates’ theory is known as the “bricks and mortar” theory of genetics and states that taxonoomical material consists of physical substances originating from each part of the body and is concentrated in the male semen, which develops into a human within the womb. Further, he believed that physical characteristics are “acquired.” For example, a champion weight lifter who develops large biceps through training has “big bicep” parts, which would be passed to the lifter’s offspring through his sperm and result in a big-bicepped child (1). SPRING 2013
Decades after Hippocrates’ proposition, Aristotle challenged his ideas by noting that handicapped individuals with missing limbs could go on to produce children with normal limbs. Additionally, he criticized the bricks and mortar theory by explaining that people can pass on traits that appear later with age. For example, a man with a full head of hair may conceive a child and then experience baldness years later. Thus, the “hair parts” were passed on while the “bald parts” occurred later with age, contradicting Hippocrates (1). Before the era of modern genetic Carl von Linné, better known as Linnaeus, developed today’s two-part scientific naming system (1). Later in the late 18th century, French naturalist Jean-Baptiste Lamarck proposed the first comprehensive theory of evolution. Although Linnaeus held the traditional opinion that species were created with certain traits that never changed, Lamarck contradicted the creationist belief that species were immutable; he claimed that species change in response to their environments by inheriting characteristics that their parents acquire over their lifetimes. For example, for a giraffe to reach leaves to eat off a tall tree, it would have to stretch its neck. Because giraffes need to eat leaves, the giraffes that acquired longer necks from stretching would be able to pass on their modified neck lengths to their offspring and eventually contribute to a new characteristic to the entire giraffe species (1). Following Lamarck, geologist Charles Lyell contradicted the biblical statement that the earth was about 5000 years old by proposing that contemporary geographical formations such as mountains and deserts were formed by natural physical processes that occurred over millions of years. These discoveries bolstered the argument that changes over time are the result of natural rather than divine intervention. While a student, Charles Darwin was
Figure 1: An section of the first printout of the human genome to be presented as a series of books, displayed in the ‘Medicine Now’ room at the Wellcome Collection, London. The 3.4 billion units of DNA code are transcribed into more than one hundred volumes, each a thousand pages long and in type so small as to be barely legible.
“The first major theory of genetics was hypothesized by Hippocrates in fifth century B.C.E. “
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