The Selfish Gene, Part I

The human body contains approximately 100 trillion cells, most of which are less than a tenth of a millimeter across. Inside each cell there is a black blob called a nucleus. Inside the nucleus are two complete sets of the human genome (with the exception of the sperm and egg cells, which have only one copy, and red blood cells, which have none).

The human genome is organized into twenty-three pairs of chromosomes. Of these, twenty-two are ordered by approximate size, from the largest (one) to the smallest (twenty-two.) The remaining pair consists of the sex chromosomes, two large X chromosomes in women, one X and one small Y in men.

Each chromosome contains several thousand instructions (genes), which can be broken up into paragraphs (exons), which are interrupted by interference (introns). Each paragraph can be further broken down into words (codons) written with letters (bases). There are one billion words in a gene, making it longer than 800 Bibles.

In between the paragraphs of useful information (exons) lie long stretches of random nonsense and repetitive strings or irrelevant code (introns). Hidden in this immense code is the dirty secret of the genome – each gene is far more complex than it needs to be. The reason for this confusion is that the genome has been adding, deleting, and amending in the process of self assembly for over four billion years.

What makes this nonsense code in the genome so fascinating is that because it is self-replicating, it is prey to parasitism. In fact, the gene is riddled with the equivalent of computer viruses… selfish, parasitic stretches of letters that only exist because they are adept at getting themselves duplicated. The Human Genome Project found that about 35% of our DNA is so-called “junk code.”

Just as the code of the genome is the survival mechanism for these meaningless bits of DNA, which exist only to exist and reproduce, the more we learn about genetics, the more it seems like the human body is merely the survival mechanism for our genes to exist and reproduce.