The end of the year is usually the time when people pause and take stock of things: what was accomplished over the course of the last twelve months and what does the next year have in store? Part of this assessment often entails reflecting on the mistakes of the past, things that nobody wants to repeat in the upcoming future. And at the same time, the hope is to repeat those things that turned out right.
Evolutionary biologists routinely reflect on the past, taking stock of life’s history. But many believe the history of life can’t be repeated because biological and biochemical evolution at its most fundamental level is governed primarily by chance. Evolutionary pathways consist of a historical sequence of random genetic changes operated on by natural selection, which, too, consists of chance components. The consequences are profound. If evolutionary events could be repeated, the outcome would be dramatically different every time. The inability of such processes to retrace the same path makes it highly unlikely that the same biological and biochemical designs should repeatedly appear throughout nature (a concept known as convergence).
And yet, over the last decade or so, evolutionary biologists have discovered a number of examples of convergence at the organismal and biochemical levels. (For more information, see these articles on convergence and repeated evolution.)
In my most recent book, The Cell’s Design, I document over one hundred examples of convergence at the biochemical level. I argue that widespread occurrence of convergence among a wide range of biochemical systems raises significant questions about the validity of evolutionary explanations for life’s origin and diversity.
This past year, I wrote about one example recently uncovered in plants by scientists from Purdue University. While I’m taking some time off to celebrate the Christmas and New Year holidays I would like to repeat this entry.
Happy New Year!