Although we’re still in an ice age, we are currently in an interglacial period. That’s a good thing, since glacial periods are truly unpleasant – dry, cold, low biological productivity, high variability. Low CO2 concentrations made plants more susceptible to drought. Peter Richerson and Robert Boyd have suggested that the development of agriculture was impossible in glacial periods, due to these factors.

There was an earlier interglacial period that began about 130,000 years ago and ended about 114,000 years ago. It was a bit warmer than the current interglacial (the Holocene).

The most interesting events in the Eemian are those that didn’t happen. In the Holocene, humans developed agriculture, which led to all kinds of interesting trouble. They did it more than once, possibly as many as seven times independently. Back in the Eeemian, nichevo. Neanderthals moved father north as the glaciers melted, AMH moved up into the Middle East, but nobody did much of anything new. Populations likely increased, as habitable area expanded and biological productivity went up, but without any obvious consequences. Anatomically modern humans weren’t yet up to displacing archaic groups like the Neanderthals.

So, it is fair to say that everybody back then, including AMH, lacked capabilities that some later humans had. We could, if we wished, call these new abilities ‘behavioral modernity’.

The Bushmen are the most divergent of all human populations, and probably split off earliest. They are farther from the Bantu (in genetic distance) than the French or Chinese are.

According to some models, this split (between the Bushmen and other populations of sub-Saharan Africa) occurred more than 100,000 years ago. Recent direct measurements of mutations show much lower rates than previously thought, which tends to place such splits even farther back in time.

The question is whether they split off before the development of practical behavioral modernity.