It seems like most of the readers in the ScienceBlogs universe don’t understand the difference between evolution and natural selection. When Razib asked them to provide the thing they would want the public to understand about evolution (in ten words or less, mind you), most of them provided explanations of natural selection. Let me say it as clearly as I possibly can, evolution is more than natural selection.
I am not a neutralist. Check out the archives of this blog for a taste of my selectionist leanings. Additionally, a large portion of my research revolves around understanding how natural selection operates on DNA sequences. That said, we cannot disregard the importance of stochastic processes. At the molecular level, stochasticity is summed up by the neutral theory (and its kissing cousin, the nearly neutral theory), which provides an excellent null hypothesis when we would like to detect selection. That’s why population geneticists spend time doing coalescent simulations — so that we’re sure that the patterns of allelic variation are due to selection and not some confounding variable such as drift or population structure.
If one wishes to understand evolution, one must understand natural selection. But to truly appreciate natural selection, one must also understand the simplest alternative, a Wright-Fisher population. That is to say, in the absence of selection, what happens? Well, allele frequencies change due to random sampling. The difference between selection and drift is that the former is deterministic whereas the latter is stochastic.
In the comments on Razib’s blog, I argued that differential inheritance of allelic variation (whether it be by stochastic or deterministic mechanisms) is the key to understanding evolution. Most people were getting caught up in unequal transmission due to fitness difference (ie, natural selection), and ignoring the stochastic effects. Whittling down my ideas into ten words left me with this:
Differential inheritance of genetic variation via stochastic and deterministic forces
That is evolution in a nutshell. Now all we need to do is make sure the public understands the definitions of the big words I used (you know, everything other than “of” and “and”).
I also like John Hawks’s explanation: “No evolution means equal offspring for everyone!” The only thing missing is that inequalities in the number of offspring can be due to random sampling or selection.