Thursday, July 20, 2017

Mutations More Common, Less Harmful Than Previously Thought

We are all mutants. The 3bn pieces of DNA that make us who we are were long thought to be constant, chiselled in granite like a classical monument, with only tiny changes made here and there. Scientists used to believe that DNA mutations were largely harmful.
By the late 1990s and early 2000s, as the first sequences of the human genome came rolling in, researchers realised that their view of mutations was completely backwards. Instead of being rarities that almost inevitably harm health, mutations litter the human genome. The average human carries around 400 unique mutations, and most of us are none the worse because of them.
Mutations are at the core of evolution; lack of knowledge of them was for many years a large problem with Darwin's theory.  Creationists have long used the apparently high lethality of mutations as arguments against evolution; pretty clearly, even if 99% of mutations were lethal or even no advantage, it would not impair evolutionary theory.  If at least some tiny fraction of mutations provide a clear advantage in some environment, that would be enough.

But if the mutations are widespread and generally have no effect, it suggests that biologists have been working with wrong assumptions for a very long time.  This is part of why arrogant assumptions about knowing how evolution works are unwise.  There is still a lot to learn.

2 comments:

Karl said...

This might be more of a challenge to biology if it were actually news.

Rhonda Cramer said...

Well said. Perhaps the whole notion of "mutations" should be revisited and thought more of "adaptability strategies." Rigidity in the genetic code provides stability as long as the environment remains constant. But, change is inevitable in physical universe, and the ability of the code to have inherent in it the capacity for change and thus adaptability points to divine design. The design using mutation as the source for adaptation is brilliant. Otherwise, the world is filled with koalas, who can eat only one kind of eucalyptus. Woe to the koalas if a blight took out all the trees. Woe to us if we lacked a capacity to change.