Bab al Mendab and Sinai adequately. Additionally, a [*switch*]{} (see: Section \[subsec:geographicalmaps\]) which would allow passage at the Bering Strait seems unnecessary due to the interesting coincidence that the hominin wave front reaches this passage at the beginning of the last ice age. If it were blocked previously, this would have had no effect.

The core computations performed by our solver are *independent* tridiagonal solutions, which can be easily parallelized to deal with larger grids. In order to further improve numerical performance, in the Appendix \[sec:code\], we discussed a compressed storage scheme to integrate the Fisher/KPP equation on a projected world map (or any other irregularly-shaped domain). The alternating direction scheme discussed in Section \[sec:Godunov2Dsplitting\] also works with this compressed storage. In the case of world dispersal discussed in Section \[sec:dispersal\], since about 71% of the earth’s surface is water, this compressed storage reduces computational work by the same amount.

Provenance {#provenance .unnumbered}
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For this paper, the simulations were run on either a Mac Mini, 2.4 GHz Intel Core Duo (Mac OS 10.6.8), or a `MacBook` laptop with the same processor specifications but running OS 10.8.4. On the Mini, `MatLab` (7.10.0.499) R2010a was used, respectively (8.1.0.604) R2013a on the 