Notable paper: William Hutchison et al. (2016) A pulse of mid-Pleistocene rift volcanism in Ethiopia at the dawn of modern humans. Nature Communications 7, 13192. doi:10.1038/ncomms13192
Synopsis: Many of today’s lakes and volcanic calderas of the central Ethiopian rift were the outcome of a cluster of volcanic activity between 320,000 and 170,000 years ago.
Interesting because: Early examples of Middle Stone Age (MSA) archaeological industries were developing at this time, and possibly the immediate ancestors of most of today’s gene pool were making some of them. Volcanoes might have affected the local environment.
KILL THIS QUOTE WITH FIRE: “current evidence overwhelming [sic] suggests that all major events in hominin evolution occurred in East Africa”. No. Just no.
Bottom line: It is very hard to test how local environmental shifts may have affected hominin populations; either prompting adaptation or creating population sinks. My guess would be that a region full of active volcanoes probably acted either as a sink or a barrier to gene flow. As an extreme, these volcanoes may have impeded migration from the Afar region further south along the African rift during the later Middle Pleistocene, making this fossil-rich region a relative cul-de-sac. However, in my opinion a 30-km zone of unpleasantness surrounding a volcanic caldera is not much of a barrier to mobile and interconnected hominin populations. Ancient people probably looked in wonder at the great forces within the earth, and watched their children played in the snowing ash.