Originally posted by znsho
What puzzles me more than anything is why is the genetic code universal? One would think that benificial mutations changing the code would have occurred. Yet, it has remained unchanged bewteen species.
I think that’s a good question and one that I have been puzzling over.
Actually, if you count viruses as “life” (many people wouldn’t) then the genetic code DNA is almost but not quite universal because although some viruses are classed as “DNA viruses” meaning that they carry DNA but other viruses are classed as “RNA viruses” meaning that they only carry RNA and no DNA! -but that would be the only exception to that rule.
There are actually good reasons to believe that DNA is not the most perfect molecule for life to use to store genetic information! For a start, it is easily damaged by the presence of oxygen unless there are enzymes present that constantly repair that damage as quickly as it occurs. But the first life formed in anaerobic conditions and so this wouldn’t have been a problem for the first life.
But, given the fact that DNA is far from being the perfect substance for life to use in our oxygen rich environment, this begs the question of why evolution didn’t make it evolve into a more suitable substance? I think this is just another example of “evolution’s blunders” but also of evolution just making the best of a bad job (by, for example, evolving enzymes that constantly repair damage to DNA as quickly as it occurs). But I also have formed the theory that although evolution is good at rearranging things that it has already created, what evolution finds extremely hard to do is change the basic chemical building blocks of life once they have formed. So once the basic chemical building blocks of life have formed (such as DNA bases and amino acids etc) then, whether they have a good design or not, life is just stuck with them and if they are not ideal then that is just tuff.