The theory of evolution holds that all the lifeforms on Earth have a common ancestor. The process works through what is known as variation and selection over a period of time, which is roughly taken to be four billion years.
Variation is a term used to describe how an organism’s offspring is not an exact copy of its parents. Selection occurs when some of an organism’s offspring produces more of their own offspring. Common ancestry does not mean that species have evolved from each other. For example, chickens did not evolve from cats and humans did not evolve from chimpanzees. Instead, what evolutionary theory holds is that if one were to go back far enough in time one will find a “grandparent” of which both organisms are descendants.
Is evolution a theory in crisis? One writer for an Intelligent Design website maintains that it won’t be too long until the “evolution bubble is about to pop” (1). But this is far fetched. It is true that scientists debate the specifics of the theory, after all, that is how science functions. Although debates exist across several areas (i.e. the extent to which variation is explained by random genetic mutations and how important other selection mechanisms are beyond reproductive fitness), the general framework of evolutionary theory which includes the common descent of all species is widely supported. The theory does not present any reason to believe that it will be “popping” any time soon. For example, 98% of the members of the American Association for the Advancement of Science (AAAS) accept human evolution. According to the American Association of University Professors, “The theory of evolution is all but universally accepted in the community of scholars and has contributed immeasurably to our understanding of the natural world” (2). National Association of Biology Teachers Scientists claims that scientists have “firmly established evolution as an important natural process” (3).
Although many religious people still struggle to accept evolutionary theory (4), an increasing number of religious organizations are receiving it warmly. Biologos, for example, explains that “There is very little debate in the scientific community about this broad characterization of evolution”, and they seek to present harmony between religion and evolutionary theory. The group claims that “the observational evidence explained by common ancestry is overwhelming. Of course, new data causes scientists to adjust some of the specifics (like how long ago species diverged, or which species are most closely related), but this core view is overwhelmingly supported and agreed upon by the vast majority of scientists in the field” (5).
Some critics of evolution charge that it is “just a theory.” In other words, it is just an idea that scientists uncritically accept. But this is not accurate. Although it is true that evolution is a theory, just like the theory of gravity and the Big Bang, and is therefore open to falsification, this is not to say that it is an unconvincing idea. Hypotheses that are tested and do not stand up to scrutiny are revised or rejected. For a hypothesis to constitute a theory scientists must agree that it is supported by persuasive evidence and has explanatory power. The following explanation offered by Biologos is sufficient,
“In non-scientific contexts, “theory” usually means something like a guess (e.g., I have a theory about…). But in its scientific sense, a theory is a tested and well-confirmed explanation for a set of observations. The observations explained by the theory of evolution come primarily from the fossil record, comparative morphology, biogeography, and now most importantly, genetics. Evolution does not attempt to give a scientific explanation for the origin of life, but only for the development and diversification of lifeforms after the first life began” (6).
1. Luskin, C. 2014. What to Expect When the Evolution Bubble Is About to Pop. Available.
2. American Civil Liberties Union. n.d. What the Scientific Community Says about Evolution and Intelligent Design. Available.
3. American Civil Liberties Union. n.d. Ibid.
4. Nadelson, Louis., and Hardy, Kimberly. 2015. “Trust in science and scientists and the acceptance of evolution.” Evolution: Education and Outreach 8(9); Pew Research. 2015. Chapter 4: Evolution and Perceptions of Scientific Consensus. Available.
5. Biologos. What is Evolution? Available.
6. Biologos. What We Believe. Available.