Question concerning evolution

Yeah, when I read the paper I thought the same as Paul: they're not measuring time since speciation, they're measuring time since the Mitochondrial Eve of each species. There's no way their methods let them do anything else.Without even considering (as caffeine does) bottlenecks and selective sweeps, drift alone would create the same effect given long enough. How long would depend on population size; I have some spare time coming up, I'll do some simulations.

Well in that case there'd be a greater element of chance, so any particular species could look like the Flood bottleneck was 6000 years ago or 2000 years ago instead of 4000. Of course you could get round this by just looking at a large number of species and averaging. (Just don't use kosher species because there were more animals per species of them on the Ark.)