Genetics is the study of genes and inheritance in living organisms. This branch of science has a fascinating history, stretching from the 19th century when scientists began to study how organisms inherited the traits of their parents, until today when we can read the “source code” of the living beings letter by letter.
Genetics started with curiosity about why things are the way they are: why do children look more like one parent than another? Why do some species resemble each other more than others?
It has become an almost universal answer manual for biology. By reading the “source code” or “model” of an organism, scientists today can often determine exactly where an organism comes from, how it has changed over time, what diseases it might develop, and how its life processes are similar to or different from those of other organisms.
In the 19th century, offspring were known to resemble their parents, but it was almost unknown why this happened. Why did some children “take” one parent, but not the other? Why can plants and animals have offspring that you have not seen in either parent? Why do some species resemble each other more than others?
In the 19th century, Gregor Mendel began to examine inheritance systematically by raising pea plants. He tracked various traits of pea plants over several generations, recording what kinds of parents had what kinds of offspring. He successfully derived the mathematics behind the dominant and recessive genes, the first empirical evidence that the traits were actually transmitted in any measurable way from parent to child.
The following image shows a Punnett square of Mendel’s pea plants. Punnett Square was developed by English geneticist Reginald Punnett to visually represent how dominant and recessive traits were transmitted to offspring. The mathematics produced by the Punnett square coincided with the results that Mendel found in his practical studies of pea plants.
Around the same time, Charles Darwin was writing “The Origin of Species,” after examining changes in the features of the island’s finches in times of drought and abundance. Darwin concluded that finches that had the most suitable traits for survival were more likely to survive to transmit those traits, producing changes in the traits of the general population over time.
His work, when taken in conjunction with Mendel, began to suggest that all species on Earth could be related to each other, and could have gradually drifted apart by inheriting different traits through natural selection.
From there, the field of genetics slowly advanced. In the early 20th century, scientists using light microscopes powerful enough to see the nucleus of a cell suspected that chromosomes were the seat of genetic information. They were able to connect chromosomal inheritance with trait inheritance, demonstrating that “instructions” for inherited traits were transmitted on chromosomes within the nucleus of eukaryotic cells.
The next big leap in genetics began in the late 20th century when technology became available to read the nucleotide “source code” of the genome. Since then, the technology has become faster, more affordable, and more accurate, allowing scientists to sequence entire genomes of many organisms and compare them.
Impact of genetics
The ability to read the “source code of life” has led to a revolution in the way we think and classify organisms.
Before the advent of gene sequencing, scientists guessed the relationships of organisms to each other by studying their physical characteristics. Organisms with similar characteristics were often assumed to be related, although many examples of convergent evolution were known, where two unrelated organisms develop the same traits separately.
With the advent of gene sequencing and molecular genetics, referring to the ability to read the DNA molecule at the molecular level, it became possible to trace lineages of descent directly. Scientists can now read the source code of a cell and determine where and approximately when an organism’s genome changed.
As a result, it is now known that a large amount of material that was taught in schools just ten years ago is incomplete. Archaea and bacteria, once classified in the same kingdom, are now known to be genetically very different from each other. Mushrooms are now known to be more closely related to animals than plants. Many other fantastically bizarre and fascinating discoveries have emerged from the genome revolution, each of which takes us one step closer to understanding what makes us who we are and how we are interconnected.
Genetic sequencing has also led to a revolution in the way we think, diagnose, and treat disease. In many cases, it is now possible to know how likely a person is to contract a given disease by looking at their genome.
Scientists hope this will lead to great revolutions in medicine for centuries to come: As medicine reaches genetics, it will one day be possible to determine which medicines will work best in disease or what lifestyle changes will support a person. heals simply by reading your DNA.
This has also led to new ethical and economic challenges.
Some women whose genes have certain BRCA1 / 2 gene mutations, for example, choose to have their breasts and ovaries removed even if they are healthy, because they know there is a high probability that they will develop cancer in these organs.
In 2013 Angelina Jolie made the headlines by publicizing her choice to have her own breasts removed after discovering through a genetic test that she had an 87% chance of one day getting breast cancer.
In other cases, geneticists may tell people that they will develop a serious illness, but they don’t yet have the tools to prevent it from happening. People in families with Huntington’s disease, for example, can find out if they have the gene for this devastating and inevitably fatal dementia. But what can they do with this information?
An unexpected economic challenge has come from health insurance companies. Insurance companies have always made their money betting on who might get sick and who might not. Now that tools are in place for companies to find out who is most likely to get sick in very fine detail, concern has been raised that people with unhealthy genes may charge much more for health insurance than people with genes healthy.
Genetic Definition, History, And Impact