The phylogenetic position of the Yunxian cranium elucidates the origin of <i>Homo longi</i> and the Denisovans.

Abstract

Diverse forms of <i>Homo</i> coexisted during the Middle Pleistocene. Whether these fossil humans represent different species or clades is debated. The ~1-million-year-old Yunxian 2 fossil from China is important for understanding the cladogenesis of <i>Homo</i> and the origin of <i>Homo sapiens</i>. In this study, we restored and reconstructed the distorted Yunxian 2 cranium using recently introduced technology. The results show that this cranium displays mosaic primitive and derived features. Morphometric and phylogenetic analyses suggest that it is an early member of the Asian <i>H. longi</i> clade, which includes the Denisovans and is the main part of the sister group to the <i>H. sapiens</i> clade. Both the <i>H. sapiens</i> and <i>H. longi</i> clades have deep roots extending beyond the Middle Pleistocene and probably experienced rapid early diversification. Yunxian 2 may preserve transitional features close to the origins of the two clades.