I've been reading guns, germs and steel by jared diamond. in it, he estimates that the spread of humans to the americas, starting from an initial entry point up in alaska, took around 2000 years to arrive at tierra del fuego. he often talks about technology, language, culture and human populations spreading by "diffusion".

assuming "diffusion" is an accurate model for the spread of humans, what is the effective diffusion coefficient of human hunter-gatherers? you can assume this is essentially a 1d process, since there are bottlenecks along the way (most notably central america) that restrict flow to narrow geographical passages. i took the alaska - argentina distance from here (48,000 km); yes, i realize the pan-american highway hadn't been built yet in 14000 bc but presumably it's a decent estimate of the total overland distance from upper alaska to the southern tip of south america. nothing m2/s