When Charles Darwin wrote “On the Origin of Species”, he wrote about the difficulty of determining the actual mechanism of change in species from generation to generation. He was quite sure that the environment played a role in the final outcome of things via a survival of the fittest system. The problem in the theory of evolution was not that the strong thrive and the weak perish, because that is obvious. The problem is how does a species actually evolve? Darwin rejected the idea of incremental change over a long period of time as the likely cause of evolution. Instead, he looked at domesticated animals and observed how they could change over several generations by selective breeding. He thought that a mechanism similar to this, some sort of selective breeding that occurred in the wild, was the most likely mechanism of evolution. The “selective” breeding would occur between organisms that happened to be in the right place at the right time under the right conditions and they also happened to have the right genes for producing a successful hybrid. His theory was, in essence, that change in a species occurred due to a “natural” and chancy form of selective breeding. It wasn’t random change, it was more like lucky change. His theory then goes on to state the almost obvious: those changes that result in better adaptations to the environment result in better survival rates.
Darwin borrowed from the environmental theories of Malthus and concluded that as supplies of food increased in nature and animal populations thereby increased that those individuals most suited to the environment would prosper more than those who had been born slightly less suited. It was the principle of survival of the fittest. These survivors would then breed and the next generation would have the traits of the survivors. This was Darwin’s theory of evolution. The problem was, as Darwin admitted, how, exactly, does this generational change occur?
Many people take Darwin’s theory of evolution and proclaim that it is based upon random changes that occur in genes and those which help an organism to survive lead to successful adaptations while those random changes that hinder survival result in population declines. Darwin never advocated a theory of random change. His theory was more like a theory of natural selective breeding where the strongest get to breed and their traits are passed on to the next generation, very similar to what he observed in the farms of England.
Recently, genetic scientists have discovered that Darwin was wrong. It turns out that genetic change does not have to happen by selective breeding. It can happen by direct impact of the environment upon an organisms DNA. This new discovery states that the vast majority of our DNA, usually referred to as “junk DNA”, is not junk after all. Much of the human genome has been decoded so that we know where the code is in our DNA for blue eyes, or our blood type or even if we have a predisposition to some forms of cancer. Yet, the vast majority of our DNA is referred to as “junk”. That’s because scientists didn’t know what its function was – or if it even had a function.
In an article recently published in the New York Times , Gina Kolata writes that gene switches in junk DNA, “play critical roles in controlling how cells, organs and other tissues behave”. She states that, “…the environment can affect disease risk. In the case of identical twins, small changes in environmental exposure can slightly alter gene switches, with the result that one twin gets a disease and the other does not.” It stands to reason that if the environment can change junk DNA and then cause a disease, it can also cause a change that results in resistance to disease or perhaps some other very different result. The real discovery here is that a mechanism has been discovered that can cause human DNA to rapidly modify itself in response to a factor in the environment. This must be the cause of evolution.
While the Times article is primarily focused on diseases being caused by exposing junk DNA to certain substances, it is only reasonable to ask whether this is in fact the mechanism of evolution. It is a direct connection between the body’s genes and the environment. Certainly, there will be cases where the environment contains toxins and these toxins will harm the DNA and cause disease. However, this is very likely the mechanism of evolution also. It is the way in which the body’s DNA senses that the environment is changing and tries to make the appropriate response. This is very likely the true mechanism of evolutionary change. It also explains why evolutionary change is, as Darwin noted, fairly quick and not a progression of minute changes.
It seems that Darwin’s notion of selective change occurring because of the coincidence of the right circumstances for the right individuals is not the likely explanation for evolution. It seems far more likely that our “junk” DNA is not “junk” at all, and it is this DNA (it actually comprises about 90% of our DNA) that results in “evolutionary” change. It seems that just as we are able to make conscious adaptations to our environment that there is another level of consciousness in our bodies, that we are unaware of, that is also continually working to optimize our body’s response to the environment and also that of the next generation of human beings.
Junk DNA is how evolution works.
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