Evaluating refugia in recent human evolution in Africa: Supplementary information

Homo sapiens have adapted to an incredible diversity of habitats around
the globe. This capacity to adapt to different landscapes is clearly
expressed within Africa, with Late Pleistocene Homo sapiens populations
occupying savannahs, woodlands, coastlines and mountainous terrain. As the
only area of the world where Homo sapiens have clearly persisted through
multiple glacial-interglacial cycles, Africa is the only continent where
classic refugia models can be formulated and tested to examine and
describe changing patterns of past distributions and human
phylogeographies. The potential role of refugia has frequently been
acknowledged in the Late Pleistocene palaeoanthropological literature, yet
explicit identification of potential refugia has been limited by the
patchy nature of palaeoenvironmental and archaeological records, and the
low temporal resolution of climate or ecological models. Here, we apply
potential climatic thresholds on human habitation, rooted in ethnographic
studies, in combination with high resolution model datasets for
precipitation and biome distributions to identify persistent refugia
spanning the Late Pleistocene (130-10 thousand years ago). We present two
alternate models suggesting that between 27-66% of Africa may have
provided refugia to Late Pleistocene human populations, and examine
variability in precipitation, biome, and ecotone distributions within
these refugial zones.