The journey of humans on Earth has always been a pitch of crests and troughs. Every crest leads to a new extinction and every trough leads to a new mutation. But, what’s even more interesting is the entire path that led us to today, the path of EVOLUTION.
Evolution has always been a very complicated phenomenon where we have lost a lot of unnecessary features of the human body and gained other ones. But, during this entire process of loss and gain, what remained constant was the ideology to get the body to a more optimised and well suited stage. But, not always has this been the case. In some cases, we have also lost some really important features which would have otherwise proved to be of great significance now. For eg: LOSS OF THE GENE ENCODING FOR VITAMIN C.
The gene-GULON:
Any chemical product formed in our body is through various chemical reactions involving various enzymes acting on their specific substrates. We all know that humans cannot synthesise vitamin C, but do you know that it’s only the modern humans who are unable to synthesise this vitamin. Our ancestors, however were very much able to synthesise it. Albert Lehninger in 1957 studied vitamin C biosynthesis and later developed that the conversion of glucose to ascorbic acid (or to what we call vitamin C) is a series of reactions involving various enzymes. Humans lack the final enzyme for this pathway i.e. L- gulonolactone oxidase required for the conversion of 2-keto-Gulono-gamma-lactone to L- ascorbic acid.
GULON is the gene responsible for synthesising L- gulonolactone oxidase. GULON, unfortunately in humans, is a pseudogene. Pseudogene, meaning that at some of point of time, it was actively synthesising proteins but, in inactive now, although still present in our DNA.
Evolution vs GULON:
The bigger question however is, that how did evolution led us to the loss of an enzyme that could have been so crucial in times like these, when all we want our diet to be rich in is Vitamin C. The answer to some may seem very hypothetical but apparently, is the only possible explanation to it. It can be broadly divided into two possible explanations:
1. As we started evolving, we started exploiting more and more nutritional fruits and vegetables, most of which were rich in Vitamin C and therefore, we gradually started fulfilling our Vitamin C requirement from the diet itself, thus, making the body lose the need to synthesise it itself.
The second possible explanation will seem a bit more logical to most of the readers out there.
2. The loss of this gene was associated with the indirect gain of some other features. This was thus appreciated by the nature and was carried forward to next generations. Elaborating the same, the synthesis of vitamin C led to production of peroxide molecules in the body. These molecules are very harmful and a toxic product for human body. The loss of GULON also led to the decreased production of peroxide molecules which was highly favoured by the nature.
But, whatever be the explanation for this major loss, we all have to agree on one point, that evolution did prove to be a bit harsh considering the current scenario of the world. Evidently, a human race with GULON as an active gene could have been far more immune than the current Homo sapiens. Nonetheless, we all finally know that:
Evolution is like An Indian father, ALWAYS thinking for your best future possibilities, but seldom making them the worst.