How did the discovery of DNA prove that Darwin’s theory of evolution was correct?
Charles Darwin and his theory of evolution was only just a theory, until the discovery of DNA which helped prove his theory to be fact. How it did it is this: it explained that Darwin’s hypothesis of observed animals such as the finch, evolved over time to fit their environment. He observed that the beaks of finches matched the food they ate, which was explained by the DNA due to the genetic mutations that take over a population due to their fitness. The finches had their genetic code mutated over time to increase the ability to eat, which demonstrates species change as Darwin had hypothesized. It also explains the family lineage that Darwin observed regarding how different species are closely related to others. Darwin had proposed his “tree of life” theory in which species diverged out like branches off a tree. (Example below)
We now know that there is more crossbreeding which means that it has become more of an intertwined web of sorts than we previously thought, but Darwin was still correct and the discovery of DNA that proved genomes of species closest together had more genetic similarities proved Darwin’s theory correct. If it were not for the discovery of DNA, Darwin’s theories of evolution would not have been proven scientifically correct due to the nature of the reasons as to how exactly it happens. As a result of the understanding that brought us, we are able to continue using DNA and finding new undiscovered links Darwin could have never thought of.
How does it change the way we view evolution today?
The discovery of DNA helped prove that we have similar DNA to species closest related to us such as chimps. We share 98% of our genetic code with them and come from common ancestors, but with minor variations in our genetic code, we have had insanely large implications and effects on our ability to thrive as a species and how we view our relation to other organisms.
The discovery changed the way we view evolution today, because now we can see which species we actually are related to, as well as a glimpse into our genomes. We can see this in the way that embryotic help form our understanding of common ancestors. Embryos generally all use the same genes that are building blocks before creating a more complex organism. It is in this process of development that we are able to see the common traits and helps scientists link them to specific common ancestors. For example: the tortoise, chick and human all have a similar form which continues as they develop, with humans becoming more distinct in particular. Meanwhile, the fish becomes completely different from the other three. The reason this occurs is because of the common genetic components that the three land animals have developed over time with their ancestors. This would not be possible without the work of tracking those genes that are crucial in pinpointing traits and observing their use in the organism to help its fitness. (Picture from class notes. Credit: Ms. Mireau)
Another way the discovery of DNA helps our understanding was mentioned above and that is our relationship to other animals. Humans are positioned at the top of the evolutionary tree, because we are the most advanced as we have come to take over the world. What is less well known is what caused us to get here, which is our genetics. As a result of the fact, we are so genetically similar to chimps, the specific mutations have great impacts on how our bodies differ. What makes us different is the genes that control our brain and hands. A difference between us and chimps is the fact that our skull continues to grow which is thought to allow our brain to grow and expand as well. We also received thumbs, which is greatly important to our motor functions and has in large part helped us succeed as a species. Without this understanding of which genes have their specific effects on humans, we would not be able to pinpoint our success and what differentiates us from other species.
How does it change the way we view evolution into the future?
As technology advances and we gain a greater understanding of genetics, the science not only becomes observing and mapping, but also the altering of said genes. The new technology called CRISPR helps our understanding of what exactly makes us different from one and other. Many genes are basically switches, that turn on and off depending on the use which dramatically affects our appearance. For example: a person’s eye colour is a washed our shade of blue because of the switches turned on for the colour blue and is faded because of the fact that the switch is not completely turned on. This understanding will help us in the future to specifically identify which genes code for different traits, behaviours and even illnesses. The importance of this technology cannot be understated as we head into the future because we may be able to mess with our genetic code which negates the point of evolution. If form follows function, we cannot play with artificial features without having a specific function. There is no certainty that evolution and its role in genetics are intertwined, but the future may involve a more interactive role in how we deal with our genome and those of other organisms.