7 - Evolution of developmental processes

Summary

Evolution is a fact. No serious biologist disputes that organisms have changed over time or that they continue to change. Other organisms have become extinct, many of them in recent times. What requires explanation is the way in which these changes take place. Darwin observed that members of a species differ from each other, that some were more likely to survive and reproduce than others, and finally that the characteristics of the fitter individuals would generally be inherited by their offspring. So, by the process he metaphorically termed ‘natural selection’, lineages would evolve. Like his contemporaries, Darwin knew nothing of the molecular processes of inheritance and was often tempted into supposing that acquired characters could be inherited, arguing for example that behaviour patterns that are learned generation after generation will eventually be expressed without being learned. In the mid-twentieth century, the genetic mode of inheritance which had become established at the beginning of the century was brought together with Darwin's evolutionary theory in what was called at the time the Modern Synthesis. This conceptual framework became the dominant mode of biological thought, emphatically reinforced by the culture of genetic determinism that has accompanied the explosion of genomic knowledge.

Evolutionary theory itself continues to evolve, integrating the views of the Modern Synthesis with the explosion of observation and theory coming from the developmental, ecological and molecular sciences (Pigliucci and Müller,2010). Other mechanisms of inheritance have been discovered.