In case you haven’t heard the news, researchers in Texas have recently declared that, based on their analysis of human genes, about eight percent of the human genome comes from viruses. Almost a tenth of your own DNA, then, comes from tiny infectious particles that most scientists don’t even consider to be alive. Viruses are composed of protein coats surrounding packets of genetic information. When they infect you, they hijack your own cells’ machinery to create new viruses from their own genetic information. Some forms of viruses go so far as to splice their own genomes into yours, meaning that various stretches of DNA in your cells are actually viral stowaways, making use of your cells to replicate themselves.
Let’s pair this with another number you’ve probably heard: that humans share upwards of 90% of their genes with apes. Most of our genes are exactly the same as those found in chimpanzees and gorillas, and as we move to simpler animals we find that we still share a substantial portion of our genes with creatures like dogs, mice, starfish, and oak trees. We even have some genes that are identical to those found in the simplest form of life, single-celled bacteria.
Faced with such remarkable statistical similarities, some scientists conclude that there is no real difference between human beings and apes, bacteria, and viruses. The less scientifically stunned stand back and scratch their heads, wondering how it is that holding a Ph.D. in biology can lead a man to believe that a mindless subcellular infectious agent isn’t really all that different from the species that painted the Sistine Chapel, wrote the Divine Comedy, and flew to the moon.
The problem is reductionism, the idea that beings can be reduced to merely their parts. This idea holds that the sum of the parts is all that a thing is. On the other hand, the common sense perception that viruses and people are clearly different things, however much they may share genes, is a recognition of the fact that the form of a thing matters just as much as does the matter that makes it up.
The key point when evaluating humanity is not whether it was made immediately from dirt (as a literalist reading of Genesis would imply) or whether it was made from dirt in the form of organisms passing through various stages of descent (as in the case of evolution.) In either case, the key distinction is the same: this particular dirt, this particular body, has been given an immortal soul. As such it is irreducible to mere description of its physical components.
Catholic thought has long been guided by Thomism, a Catholic development of the Greek philosophy of Aristotle. This system of philosophical thought was developed by Saint Thomas Aquinas and his followers, and has generally been endorsed by the Church as the best synthesis of revelation and the truths to which the human mind can come by reason. As difficult as it may be at times to read Thomas’ or Aristotle’s writings, their system of thought is based ultimately on common sense, and does not rely on counterintuitive premises.
Thomism, therefore, accepts completely the common sense intuition that viruses and people are clearly very different things, no matter what similarity they may have in their genetic material. Aristotle distinguished between the matter that makes up a thing and the form into which a thing is made. Wood may be made into a table, a chair, or a wall, and though they are made of the same material, wooden tables, chairs, and walls are different things. Similarly, the same genes and organic molecules may make up viruses, bacteria, monkeys, and men, yet they are all very different things. The Church affirms that of these four, only man possesses a form with an immortal, immaterial soul ordered towards God and eternal life.
The constant reporting of material similarities between the human body and simpler forms of life is often used to intimidate believers with the claim that man is no more than an animal. A return to the more sober thought found in Aristotle and Aquinas can help us to see the error of this charge. When we investigate only matter, we have to face the fact that the human body shares 100% of its elements with a pile of manure, 90% of its genes with a monkey, and 8% of those genes with a lowly virus. The human body may have inherited the genetic material of a long evolutionary history. Yet such a claim should bother the Christian no more than the Bible’s claim that the body is made of dirt. Our exceptional nature is not found in the listing of the basic components of our structure, but rather in the supernatural form God has given us, ordered beyond this world to the Creator of all matter Himself.