Purpose, Evolution, and Self-Replication

Richard Dawkins famously wrote: “The universe that we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil, no good, nothing but pitiless indifference.”¹

At first glance, it seems to be reasonable to see nothing but indifference “at bottom.” But the statement cannot be true for everything in the universe, for if it were, it would have been impossible to conceive of or express the idea. Purpose and good and evil have to exist somewhere for their absence to be noted elsewhere. What Dawkins is claiming leads to the conclusion that the human ideals of meaning, pity, and compassion are not to be found outside of human minds. But they undeniably exist in the part of the universe that includes human minds.

Let us consider purpose. It certainly is present, not only when it comes to human beings but in all life. I grant that bacteria do not get up in the morning and ask themselves, what should I do today?—but, like all creatures, they act with purpose, with an apparent goal, which is to remain alive and reproduce themselves, much like beavers, pine trees, fungi, and spiders. Of course, such apparent teleological behaviors that increase the chance of survival are quite different from a human’s purpose for, let’s say, writing an essay on teleology. The spider’s purpose, a biologist will insist, stems directly from the blind, purposeless, non-directional processes of evolution. The term “teleonomy” is sometimes applied to such biologically programmed purpose (as articulated by Ernst Mayr) to distinguish it from purposeful action by intentional agents. But regardless of the hard question of where and how human free will emerges, purposeful behavior seems to be a salient characteristic of all life.

We correctly look to evolution for answers about why life is the way it is, but perhaps we are not always looking at evolution the right way. Is there something purposeful about evolution that reaches beyond the simple fact that within a population of similar organisms, those with more beneficial characteristics will tend to leave more offspring? I think that there is, and to see it clearly, we should take a deeper look at the process that has been so successful at producing the enormous variety of life on this planet.

The Role of Inheritance

In many popular descriptions of evolution, only two of the three major required characteristics of living organisms—namely, their variability and their fitness in a particular environment—are presented as the mechanisms for evolution. The third component is no less critical, but it is almost always assumed and therefore not specifically mentioned. That missing piece is the amazing biological feature of high-fidelity inheritance.

Alleles are different versions of the same gene, and evolution is often defined as a change in allele frequencies in a population over time. But the production of a new allele (by means of a genetic mutation) cannot possibly lead to evolution unless it is accurately inherited by the next generation and thus able to spread through the population due to improved fitness. A mutation in a gene for a protein related to visual acuity might produce an allele that confers better eyesight in an individual bird, but if the offspring of the bird do not inherit a precise copy of the new allele, no evolution can occur.

Since long before the discovery of genetics, humans have been aware that offspring can inherit the characteristics of their parents. It is one of those facts of nature that are taken for granted. We now have learned almost all there is to know about how inheritance works, and yet it often seems that we don’t fully consider how remarkable the reality of biological replication is.

The complex molecular reactions and interactions that we think of as the defining features of being alive could theoretically exist in the absence of replication. But such living collections of metabolic chemicals could not evolve, and once their homeostasis was interrupted by some chance event, their death would be the end. Accurate replication is the ideal method to preserve the existence of life, if not the longevity of individual creatures. We see this throughout the living world, where evolution has favored widespread reproduction over individual lifespan. At the same time, there must be an upper limit on replication accuracy, since if no errors were ever made, there would be no mutations, no variations, and no evolution. In modern life the accuracy is about 99.999999%. That number might look almost the same as 100%, but in this case it is quite different, which allows for just the right degree of variation.

Replication

How did life manage to accomplish this unique ability of accurate self-replication? Think of a house, complete with walls, roof, floor, electrical and plumbing systems, appliances, furniture, books, paintings, etc. You would have a difficult time replicating that house, although after a great deal of work and time, you might come close. But no house in existence can replicate itself. And a single cell is far more complex than a house—it contains more things, and more kinds of things, than the largest apartment complex you’ve seen. A typical cell contains about ten billion protein molecules of five thousand different kinds. When we add sugars, lipids, nucleotides, amino acids, fats, and inorganic ions, the number of molecules in a cell reaches 10¹². Even I don’t have that many books in my house!

Chemicals do not self-replicate. Proteins, sugar molecules, phosphate ions, or any other of the ten billion molecules in a cell cannot replicate themselves, no matter how much energy or time is available. So how are cells able to replicate themselves and all their chemical and physical contents?