How are we made?: Even well-controlled experiments show the complexity of our traits.

Abstract

The fact of evolution seems as well established as anything in science. However, there are many questions for which we don’t yet have clear answers. That’s fortunate because it allows us to have careers in evolutionary sciences, during which we can try to understand the origin and genetic basis of traits that interest us. From what is currently understood, the development and evolution of physical and even behavioral traits are genetic at their core. We should be able to design studies to explore what that basis is. An important criterion for success in genetics, as in any other science, is the ability to frame a well-posed question on which to base one’s research. A well-posed question should enable focused research to yield a unique, clear answer. That’s particularly difficult for questions about the evolution of complex traits because we have only fragmentary physical evidence from the past; fossils that happened to be preserved, though how representative they are we can’t really say, and ancient DNA from a small number of sources. Consequently, our understanding of how traits evolved necessarily rests on historical narrative rather than on direct observation of mechanism or process. We must find indirect ways to use contemporary material to pose questions about how traits are produced and evolve. Fortunately, the same evolutionary process that generated the complex traits in our ancestors also provides connections among present-day organisms and thus suggests clever strategies we can take.