Climate stage· The columns of time

MIS 9

337 ka → 300 ka

Marine isotope stage 9, from 337,000 to 300,000 years ago, is the interglacial in which the species' oldest known fossils are generally placed.

Marine isotope stage 9, an interglacial period to which the oldest fossils attributed to Homo sapiens are generally referred. It constitutes the climatic setting within which the appearance of the species falls.

What the evidence shows

Odd numbers designate interglacials, and MIS 9 is among the warmest of the last half million years. The continental consequences in Africa are documented by the African humid periods: a compilation of continental and marine archives counts more than 230 green Sahara phases over the last eight million years, each establishing itself over two to three millennia, peaking over four to eight, then ending rapidly. During these phases, the desert carries savannah vegetation and connects the African tropics to the middle latitudes of Africa and Eurasia. The dated succession of these episodes agrees with the ages of Saharan archaeological sites and hominin fossils: these are not distributed uniformly in time but cluster in the humid intervals. The archaeological record of the desert is therefore that of its green phases, the long empty intervals corresponding to uninhabitable conditions.

Bounds and conventions

Two chronologies meet here without either constraining the other. The limits of the stage proceed from a smoothed global curve; the dating of Jebel Irhoud carries an uncertainty of 34,000 years, enough to reach the neighbouring stages. Placing the appearance of the species during MIS 9 is admissible; attributing it to MIS 9 is not.

Interglacial.