[jmmcd]

My main problem with the paper is that it's about groups, not individuals. Groyp selection has been debunked. There are better ways to think about the wider variance that don't involve groups. Think instead about each individual "gambling" in its embryology and development.

[yorwba]

Selection in the paper operates at the individual level. The groups are only a convenient abstraction to determine outcomes at the population level. You can think of group membership being determined by carrying a specific allele. Then the number of individuals in a group is just the frequency of that allele.