Here, Mackay partially contradicts himself by admitting that DNA does mean something. But he gets the specifics wrong. Let me enumerate them for you:
One: DNA is indeed a template for RNA, a nucleic acid that helps build proteins in the cell. (However, uracil replaces thymine in RNA’s chain of nucleotides.) The enzyme RNA polymerase II, works double duty as a coded instruction tape and robot assembler, reading off a segment of DNA, collecting nucleotides wondering around in the cell, and building messenger RNA or transfer RNA as it goes.
Two: Messenger RNA brings the construction plans (a copy of a segment of DNA) to the ribosomes (intricate structures, themselves made of RNA and protein), which use it to guide protein construction.
Three: Each triplet of nucleotide ‘letters’ stands for an amino acid. Think of this system as a secret decoder ring. A simple three-on-one children’s code. Transfer RNA is made up of those triplets and uses them to carry the correct amino acids to the ribosomes to be place by them in the correct order as ‘told’ to them by code carried by the messenger RNA.
Four: The cell uses similar processes to duplicate the DNA strands themselves prior to cell division. Mackay’s DNA polymerase builds up the daughter strands of DNA alongside their parent strands out of nucleotides drifting nearby. DNA stores instructions on how to replicate itself and guides the construction of RNA molecules, which carry out those instructions. In computer terms, DNA is simultaneously machine language and memory.
Five: However, mistakes do happen. DNA is not completely goof-proof in the way Mackay would have us believe. Replication of the strands can never be perfect. A triplet may be cut here; a nucleotide may be switched there. The changes that do occur in the genetic code are called mutations.
Six: This kind of mutation isn’t all there is to evolution. Sexual reproduction speeds up evolutionary change enormously. It does so by allowing cross over of segments of DNA into new sets during meiosis (cell division producing sex cells with half as many chromosomes than normal). You are not only a new combination of genes contributed by both of your parents; you are in a sense genetically engineered by the meiotic breaking apart of your parents’ gene segments into new patterns. Some geneticists argue that cross over had a much more profound impact historically than mutation did in the revving up of the engine of biological evolution.
“The main reason for controversy had nothing to do with science at all but the way people wanted to live. As Harvard Professor Stephen Gould said, ‘Now that we know we are not made in anybody’s image, we are free to do whatever we wish.’ If you want to understand the increase in discipline problems—there it is.”
I have no idea if Gould actually said these words Mackay attributes to him. All I can say is that we humans have always been free to do whatever we wished—and free to face the consequences. Cause and effect have always ruled our lives, religion or no religion.
“The issue of the origin of life is not one you can keep in science. It is all about how we want the next generation to live. If you want to teach them to believe all men have evolved with no inalienable rights, then teach them evolution only.”
Moral systems may be rocked by scientific discoveries. They may even be amended permanently. But they can never be overturned or obliterated. We are moral beings, not because we believe or don’t believe in a god. We are moral beings because our ancestors for thousands of generations had to create and sustain moral systems in order to survive. Our languages, our customs, our laws are built upon these ancient strata of historical moral systems.
If we believe that we have inalienable rights, it is because we have discovered that these rights are desperately needed in order for us to live together in reasonably coherent and orderly ways. It means that the bullies and the tyrants of old have become far too destructive to be tolerated. The 20th century saw the slaughter of millions of people. How can we avoid this in the future? By banning the teaching of evolution? I would hardly think so.