Does anyone understand enough to tell us what the "math" is all about? According to the article, the math is key to this ... yet they don't give any info at all about what that math says and how it is relevant. If anyone can enlighten us, please do!
Skimming through the supplemental information, it seems like they assume a Markov process where individuals adopt one of two strategies (with a preference towards adopting the strategy that their parent adopted), then look at which one is more likely to be dominant in the population.
In the case of kin selection in particular, the math is described by Hamilton's Rule, an inequality that must be satisfied in order for kin selection to explain a given altruistic interaction between individuals (http://en.wikipedia.org/wiki/W._D._Hamilton#Hamilton.27s_rul...).