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- Posts: 51
- Joined: December 13th, 2017, 2:05 pm
I have been reading this thread with some attention and I have to say that the subject of vitamin C and the "genes" for it go far beyond just the common "genes".
There have been studies about the whole human genome (Whole genome sequencing) that try to establish a connection between genes and certain genetic variations in the human code.
In the humans, vitamin C cannot be created because we lack an enzyme called L-gulonolactone oxidase which is responsible for the creation of vitamin C.
The loss of the "gene" responsible for this happened millions of years ago. In the first primates because the enzyme genetic family suffered mutations (which is a whole difficult and interesting story) it proved to be more beneficial there are at least a few studies that try to answer this) for the primates to not have this enzyme. Such loss of that enzyme, for example, helped increase the uric acid and other factors that helped these primates to gain weight.
Also, the body adapted to the homeostasis of vitamin C, including the homeostasis of plasma levels and many other proteins and enzymes. Numerous factors, both endogenous and exogenous, contribute to vitamin C body status, including vitamin C transporters that regulate the vitamin’s bioavailability and plasma and tissue concentrations; enzymatic reactions in which vitamin C is used up by reducing redox-active metal cofactors; and a host of environmental factors and endogenous stresses, such as oxidative stress, infection, and inflammation.
Some even proposed that the loss of an ability to synthesize ascorbic acid (Vit C) in humans may have been a critical preadaptation which markedly enhanced the survival of early man with a G6PD deficiency living in a malarial infested environment, which is hemolytic anemia.
It is also suggested that organisms without a functional GULO gene have a method of "recycling" the vitamin C that they obtain from their diets using red blood cells.
Another argument supporting the suggestion that species which have lost their GLO gene were under no selective pressure to keep it, is that all species which have lost their GLO gene have very different diets but all of them have diets rich in vitamin C. Interestingly enough, this loss of enzyme only affects the production in vitamin C but if it were in another type of enzyme, there would be severe consequences.
Also, since the diet is rich in vitamin C, the body adapted to it which means, saving "biosysntesis energy". The body always functions in a way to save energy.
Just wanted to explain in a more scientific view why we do not have the enzyme and dive in the genetics arguments.
- Burning ghost
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- Joined: February 27th, 2016, 3:10 am
I think what you've written sounds like a bad analogy of what is going on. I guess the problem is our need to divide up our experiences, which is an evolutionary requirement. It is kind of obvious to say that if we don't produce vit C then we have to get it elsewhere. It is a matter of efficiency more often than not, combined with chance. The body will have to burn energy to produce vit C, so if it can be found elsewhere then over time chance will play its part and entropy will run its course.
If we go and spend our lives living at sea we'll die of scurvy. Perhaps someone's dormant gene would switch back on through some highly unlikely epigenetic shift (but I would highly doubt that.), but more likely the human race would simply become extinct.
I've always found the term "selection" hard to stomach when talking about evolution. We select stuff, but nature is its own 'X'.
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I agree that the analogy with the software constituting this website is not a particularly close one, as others have already pointed out. But in the rest of your post that doesn't seem to be what you're saying. In the rest of the post you don't seem to be talking about the analogy at all. You simply seem to be saying that you don't believe that the Theory of Evolution by Natural Selection is a satisfactory explanation for the state of this particular gene in various mammals. Is that in fact what you're saying? It's hard to tell for sure.Burning ghost wrote:I think what you've written sounds like a bad analogy of what is going on...