Why is 90% of our DNA junk? What does this mean?Up to 90% of our DNA is useless junk which doesn't do anything. Why? Or does it do something?
It just means that there is a lot of inactive DNA; in other words, it is not actively coding for things. Only a small percentage of our DNA is "turned on"; some portions are coding for their proteins pretty much all the time, other portions only when that protein is needed. Epigenetics concerns the field of how genes are turned on and off. Evolutionarily, we have parts of our DNA that were turned on when we were more primitive organisms, and now are not used. I have read recently of research in "back engineering". That is figuring out what DNA in, say, birds, is leftover dinosaur DNA, and eventually being able to make a dinosaur. Should be interesting!
With the human genome project and the mapping of the entire human genetic code, the attention of researchers now turns towards the protein and enzymatic interactions that make genetic engineering and treatment possible. While much of our DNA is inactive, that doesn't mean it's junk. It represents evolutionary potential of the species in the future.