On this episode of Unsupervised Learning, third-time guest John Hawks returns after two years to discuss what we've learned in paleoanthropology since he and Razib last talked. Hawks obtained his PhD under Milford H. Wolpoff, and is currently a professor in anthropology at the University of Wisconsin. Hawks has also co-authored Almost Human: The Astonishing Tale of Homo naledi and the Discovery That Changed Our Human Story and Cave of Bones: A True Story of Discovery, Adventure, and Human Origins with Lee Berger.

Razib first presses Hawks on what we know about archaic human admixture into modern populations, and particularly what we've learned about Denisovans. They discuss how many Denisovan populations there were, how many Denisovan fossil remains we have, and why it has taken so long for researchers to assign a species name to this lineage of humans. Hawks also address the puzzle of the phenomenon of why there are at least two pygmy hominin populations in Southeast Asia. Perhaps humans too are subject to island dwarfism like many other mammals? Also, Razib wonders why Southeast Asia was home to such a startling variety of humans at once prior to the arrival of modern populations. They discuss all of this in light of the framework of Out-of-Africa, the recent spread of anatomically modern humans outside of Africa. Razib questions how robust this model is today given our understanding of modern humans' extensive and repeated interactions with both Neanderthals and Denisovans. Finally, Hawks covers some controversies over fossils being sent into space that roiled the archaeological world last year.