"We don't know anything of the kind. There used to be a claim around that there was an eruption (Toba) that squeezed the human population down to 70,000 or so, so that may be what you were thinking about -- but it's been debunked."
Yes...it's been debunked. I pushed this theory for years. No more.
Late Pleostocene Human Population Bottlenecks. . . (Toba)
"The last glacial period was preceded by 1000 years of the coldest temperatures of the Late Pleistocene, apparently caused by the eruption of the Mount Toba volcano. The six year long volcanic winter and 1000-year-long instant Ice Age that followed Mount Toba's eruption may have decimated Modern Man's entire population. Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago. The survivors from this global catastrophy would have found refuge in isolated tropical pockets, mainly in Equatorial Africa. Populations living in Europe and northern China would have been completely eliminated by the reduction of the summer temperatures by as much as 12 degrees centigrade. "
Hi blam: I should have included you at my Comment #88.
“The last glacial period was preceded by 1000 years of the coldest temperatures of the Late Pleistocene, apparently caused by the eruption of the Mount Toba volcano.”
Actually, this information appears to be wrong. The last glacial period began around 125,000 years ago. See my second link at #88. However, there was a distinct drop at the 74kya point which was stable for about 10ky. Then temperatures rose to where they would have been without Toba and continued to drop as I described in #88.