The Atheist's Guide to Reality_ Enjoying Life Without Illusions - Alex Rosenberg [34]
A third feature of biological evolution is the appearance of cooperative adaptations and competing adaptations. The cooperative ones are sometimes packaged together in the same organism, sometimes separated in two quite distinct ones living symbiotically (like us and the E. coli bacteria in our guts). But natural selection also, and more frequently, produces competition between genes, individuals, lineages, populations, and species. There is always the chance that an “arms race” will break out between evolving lineages of traits: a new random variation in one trait may get selected for and exploit the other traits it has been cooperating with, or a new variation may randomly appear in a trait that enables it to suddenly break up a competitive stalemate it was locked into. We will be hearing a lot more about arms races in later chapters.
Each of these three features is found in the nano-evolution of the molecules. And each persists as molecular assemblies grow in size, stability, complexity, and diversity to produce organic life.
Lock in of quick and dirty solutions: Only a few molecular shapes will ever allow for their own self-assembly and copying (by templating or otherwise). These shapes begin the lock-in that second-law processes will have to work with in building the more stable, more replicable, bigger, and more complicated molecules.
Increasing diversity and complexity: Thermodynamic noise constantly makes more and more different environments—different temperatures, different pH, different concentrations of chemicals, different amounts of water or carbon dioxide or nitrogen, or more complicated acids and bases, magnetic fields, and radiation. As a result, there will be a corresponding selection for more and more different molecules. However, they will still be variations on the themes locked in by the earliest stages of molecular evolution.
Cooperation and competition: Some of these molecules will even start to work together, just by luck having structures that enhance one another’s stability or replicability. Others will explode or dissolve or change their structures when they combine with one another. They will produce new environments that will select for new chemical combinations, ones that cooperate, ones that compete. And so on up the ladder of complexity and diversity that produces assemblies of molecules so big they become recognizable as genes, viruses, organelles, cells, tissues, organs, organisms, . . . our pets, our parasites, our prey, our predators . . . and us.
MOLECULES BOUNCING against one another inevitably follow a scenario dictated by the second law. Purely physical and chemical processes in that scenario are all that is needed for the emergence, persistence, and enhancement of adaptation through natural selection at the molecular level. Where and when molecules of some minimal size emerge, there will be some natural selection for chemical structures that confer more stability and replicability than other chemical structures confer. These chemical properties are adaptations. They have functions for the molecules that exhibit them. They enable the molecules to survive longer than less stable ones in the same chemical bath and to make more copies of themselves than other ones in the same bath. As a result of molecular natural selection, these molecules are better adapted to their molecular environment than others are.
This is an important outcome. Remember, scientism faces the demand of showing how to get the merest sliver of an adaptation from zero adaptation by purely physical, chemical, thermodynamic processes. Mother Nature can build on that sliver of an adaptation to get more adaptations and eventually more robust adaptations. But she can’t cheat. She can’t just assume the existence of that first sliver. The second law makes the first sliver possible. Variation and selection can take it from there. Now we have to show that this is the only way adaptations—molecular or otherwise—can emerge.
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