How are we made?: Even well-controlled experiments show the complexity of our traits (original) (raw)

2015, Evolutionary anthropology

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. GETTING AHEAD OF WELL-POSED QUESTIONS Upright posture and thumbs have long interested anthropologists, but we often like to think headfirst about ourselves. Much of what makes us different from other species, and perhaps more vain, has to do with our heads. However, understanding the genetic basis of the head, or its individual traits, has been difficult. Many genes that ostensibly are important to the evolution of the head have been identified because, when mutated, they can cause serious craniofacial disorders. Many or most mutational variation in those genes seems to be so serious that the embryo doesn't survive development. In that sense, more fine-tuned adaptive evolution doesn't seem to work by purging the truly pathologic genes, but more NOTES I welcome comments on this column: kenweiss@psu.edu. I co-author a blog on relevant topics at EcoDevoEvo.blogspot.com. We thank John Fleagle for critically reading this manuscript. The Box reports collaborative work done with co-investigators James Cheverud and Jeffrey Rogers, whose contact information is, respectively,