In Genome: The Autobiography of a Species in 23 Chapters (1999), Matt Ridley explains how the four nucleotides that make up DNA are grouped into three-letter “words” that designate specific amino acids. These “words” may not be Interesting to the layman, but as Ridley explains, their consistency might be.
The three letter words of the genetic code are the same in every creature. CGA means arginine and GCG mean alanine—in bats, in beetles, in beech trees, in bacteria….All life is one. We all use exactly the same language.
This means—and religious people might find this a useful argument—that there was only one creation, one single event when life was born. Of course, that life might have been born on a different planet and seeded here by spacecraft, or there might even have been thousands of kinds of life at first, but only Luca [ our “last universal (most recent) common ancestor”] survived in the ruthless free-for-all of the primeval soup. But until the genetic code was cracked in the 1960s, we did not know what we now know: that all life is one; seaweed is your distant cousin and anthrax one of your advanced relatives.
Not only, then, does all life share ancient bits of DNA but perhaps more importantly, the code by which each group of three nucleotides stands for one of the amino acids never varies in any organism. In English, “DOG” indicates a pet mammal and “LOG” indicates a part of a tree, whether the words are written or read by a man or woman, novelist or journalist, New Yorker or Angelino. The code is the same to any reader of English of every variety and circumstance and, for the purposes of this comparison, there is no language except English. In the same way, CGA always means arginine to the protein-building machinery of every human, mosquito, and marigold on the planet. There is no other code.
I had not appreciated the consistency of the genetic code before, nor that it was evidence of a single creation of life.
Ridley mentions that this evidence of a single creation might prove useful to defenders of the Bible. But it’s an argument that he dispels quickly. The genetic code may have arrived by spaceship for all we know, or it may have survived as one creation among many others that failed. No hard evidence of a deity here.
Nonetheless, he—and we—have reason to be moved. We have evidence of a single successful creation at the root of being alive, and that is reason enough to be in awe and perhaps even reassured.