Is there a need for another paper on Fisher’s runaway? The answer is not absolute, but depends on the content of the paper. I rather liked this analysis, and found it interesting to read. It also presents a theoretical underpinning for empiricists to consider further.

There needs to be a little bit more clarity as to what “runaway” means. Here it is used to mean movement away from the line of equilibrium. Movement towards is also a ”runaway”, but one that leads to an equilibrium. Consider the 1995 paper by Iwasa and Pomiankowski (Nature) which showed that given a non-linear function of costs, there could be bits of the line of equilibria which are unstable and bits which are stable (which makes sense as runaway ad infinitum is implausible). Note that if c~0, eq(1) becomes Mbar>0 (by definition holds) and h2Z>0, and eq(5) holds. I don’t impose my own view here but ask that the author makes the distinction clear to the reader. Maybe there is some simple way to distinguish runaway (movement away from the line) from the runaway process / Fisher’s runaway (coevolution of Z and M). The latter remains a key insight from Fisher.

Typo line 127, what is Y (it is M). Y also occurs later on. Then is explicit in section (b)

Typo line 344, should be Table 5