I'm reading Ernst Mayr's massive The Growth of Biological Thought, an older yet still valuable introduction (for me, at any rate) to the history and development of the sciences of biology, with particular attention to the qualitative aspect of biology (as opposed to the centrality of quantification in the physical and chemical sciences). I'm still early in the book (it's a long slog, written as a textbook for advanced undergrads, or perhaps an introductory text for graduate students) yet, the overwhelming power of evolutionary theory, especially the twin concepts of population thinking and natural selection became clear as I was reading Mayr's all-too-brief synopsis of the developments in molecular biology and ethology (the study of animal behavior) in the 20th century.
The reality is quite simple. Studying myriad animal behaviors without having evolutionary theory as the background would leave one puzzled as to both "how" and "why" various behaviors developed. With evolution through the process of natural selection as one's operating assumption, and its central concepts of population thinking - any species is a group of conspecific individuals, unique in its own right, varying slightly in adaptive fitness - and natural selection - over time, individuals in a given population pass on their genetic material that are best adapted for survival - any number of behaviors, from predator avoidance to mating and parenting become clear. Without understanding the behavior, like any other adaptation, is part of a creatures genetic endowment, and that those behaviors more likely to ensure an individual's survival are more likely to be passed on to the population as a whole, the entire thing becomes meaningless, random, and unimportant.
Similarly, the realization that various proteins and other biological molecules, while strikingly similar in atomic makeup - carbon, of course, as well as oxygen, phosphorus, hydrogen, and nitrogen - are nevertheless strikingly unique in their physical structure (Mayr discusses all too briefly the breakthrough x-ray microscopy and electron microscopy provided by giving us access to the actual 3-D structure of these molecules). Their physical structure was discovered to be key to their functions, also very highly specific. These molecules, proteins whose development is the primary function of DNA (itself nothing more than a complex protein), are not just unique in structure and function, but vary according to species. Why would one species develop one protein with a structure only slightly altered - say, a nitrogen atom in a different space - from another species? Only through the process of natural selection.
Population thinking, combines with genetics and natural selection, reminds us that any given population has varying degrees of unique individuals, with random alterations in the genetic code scattered throughout the entire population. Evolution is occurring at all levels, and throughout a given population, all the time. Only through grasping the concept of "population" and its role in natural selection, does the entire array of biological breakthroughs in the 20th (and on into the 21st) century make sense.
Virtual Tin Cup
