### On Bayes and Natural Selection

#### by F.

The Social Science Statistics Blog mentions an idea of John Baez’s that sets my little brain spinning (in a good way): the similarity of Bayesian inference and natural selection.

The analogy is mathematically precise, and fascinating. In rough terms, it says that the process of natural selection resembles the process of Bayesian inference. A population of organisms can be thought of as having various “hypotheses” about how to survive – each hypothesis corresponding to a different allele. (Roughly, an allele is one of several alternative versions of a gene.) In each successive generation, the process of natural selection modifies the proportion of organisms having each hypothesis, according to Bayes’ law….

Bayes’ law says if we start with a “prior probability” for some hypothesis to be true, divide it by the probability that some observation is made, then multiply by the “conditional probability” that this observation will be made given that the hypothesis is true, we’ll get the “posterior probability” that the hypothesis is true given that the observation is made.

Formally, the exact same equation shows up in population genetics!

Read more here. I’ll leave it to experts to judge the veracity of this idea, but it certainly is provocative.