I don't know where we are in the big cycle, but I'm almost positive it wasn't 70kya.
This post below is from an Origins forum, but I think it addresses your question about mass extinction. I think the 70kya extinction is referred to as an extinction event though, not as a mass extinction.
~Sam
Originally posted by samwik:
>Re: "I have no problem with the idea of multiple >emigrations out of Africa. There just doesn't seem to be >evidence of interbreeding with Neandertals." from -soilguy >(I think?)
Anyway, I haven't looked at the links yet but do any of them refer to how all the populations that left Africa before 70,000 yr. ago were probably wiped out by the big volcano back then. Was it Tambura***, in Indonesia? I'll go check the web, but there was a sort of "nuclear winter" back then which would explain why our diversity mainly traces back 70,000, except within Africa. Neanderthals probably did survive, being far enough away and better adapted. Basically, they could easily be the only 'out of Africa' group, from our lineage, that survived the volcano.
-Sam
***...and the next post corrects it to the volcano Toba (one of the supervolcano eruptions).
~Sam
