[ben_w]

IIRC, the rate is somewhat dynamic.

That said, my experiments in silico say that what matters most is the pressure from the utility function, more so than the rate of mutation.

So if some organism is in an environment where only a few mutations help, then evolution progresses slowly; and when most possible changes are improvements, then evolution progresses faster.

Both environments can happen even without any dynamic change to the rate of mutations themselves.