Theblogogy - The Blog of Theology and Questions

The Blog of Theology and Questions

Thursday, December 18, 2014

Define Evolution

Evolution is a hotly debated topic, especially when it comes to science vs. religion. One of the biggest contributors to this conflict is a lack of clear definitions. Once you ensure both parties are on the same page, there is a remarkable amount of agreement. Once we understand this, we can have far more positive and meaningful discussion about this important and powerful topic. What's more? Everyone can walk away encouraged to learn more and speak more kindly of the other!

The three basic definitions of "evolution" we explore in this video are:
  1. Abiogenesis - the study of how life came from non-life.
  2. Common Descent - the study of how all life came from a single life.
  3. Descent with Modification - the study of how living things change over time.

There is no scientific backing for abiogenesis. The oft-cited -- and included in textbooks -- Miller-Urey Experiment fails because of chirality. We can talk about this more in the future, but the scientific community's insistence on abiogenesis/biopoiesis is a philosophical one; important, to be sure, but philosophy, not science. There are people who are working on this, but they have yet to come up with anything. About a year ago I got to talk to some really smart people who suggested that bubbles were the mechanism by which this kind of thing could occur. Fascinating, yes, but there is more work to be done.

The science behind common-descent is actually there, but like many things in science, the interpretation of the information/facts is still up for discussion. Basically, it boils down to a question of life as a tree or an orchard. The tree of life is what you see in most textbooks, showing the splaying branches of each species' break from another. Other scientists point out that instead of a single tree, the evidence points to multiple trees, an orchard. This is absolutely something we all could learn more about as it is a fascinating and important field of research.

Everyone agrees with descent with modification. This is scientific fact and fits with any view of the world you embrace. In fact, Young Earth Creationists rely heavily on descent with modification given that God sent two of each "kind" of animal into the Ark from which all the various breeds of animals we find today spring.

Next time you find yourself discussing evolution, make sure you and the person you are talking to understand which part of evolution is on the table. Abiogenesis? Common descent? Descent with modification? Some other part of evolution? Clearing that up will enable you and your friend to have a much more productive conversation.

As always, questions and comments are welcome. Let's learn more, together!



  1. It seems to me that you cannot have Common Descent without Abiogenesis (in some form or another). Why are you choosing to draw such an arbitrary distinction?

    1. The distinction is hardly arbitrary, but a helpful one. Suppose a person believes that a supernatural power instigated a single kind of life (in lieu of abiogenesis), but that life then evolved into the multiple kinds of life we have today. Common descent without abiogenesis. "Evolution" plays a part in what that person believes in that common descent is an evolutionary process. However, the way that person thinks of evolution is different than the way someone else might understand it - evolution as necessarily including abiogenesis, for example. Without clarifying terms, it is easy to assume wrongly what other people think about about any given topic, which can make a productive discussion... difficult.