Muddying the muddle in the middle even more

Homo heterogenus: Variability in early Pleistocene Homo environments

To understand the ecological dominance of Homo sapiens, we need to investigate the origins of the plasticity that has enabled our colonization of the planet. We can approach this by exploring the variability of habitats to which different hominin populations have adapted over time. In this article, we draw upon and synthesize the current research on habitats of genus Homo during the early Pleistocene. We examined 121 published environmental reconstructions from 74 early Pleistocene sites or site phases to assess the balance of arguments in the research community. We found that, while grasslands and savannahs were prominent features of Homo habitats in the early Pleistocene, current research does not place early Pleistocene Homo, in any single environmental type, but in a wide variety of environments, ranging from open grasslands to forests. Our analysis also suggests that the first known dispersal of Homo out of Africa was accompanied by niche expansion.

Evolution of Homo in the Middle and Late Pleistocene

The Middle and Late Pleistocene is arguably the most interesting period in human evolution. This broad period witnessed the evolution of our own lineage, as well as that of our sister taxon, the Neanderthals, and related Denisovans. It is exceptionally rich in both fossil and archaeological remains, and uniquely benefits from insights gained through molecular approaches, such as paleogenetics and paleoproteomics, that are currently not widely applicable in earlier contexts. This wealth of information paints a highly complex picture, often described as 'the Muddle in the Middle,' defying the common adage that 'more evidence is needed' to resolve it. Here we review competing phylogenetic scenarios and the historical and theoretical developments that shaped our approaches to the fossil record, as well as some of the many remaining open questions associated with this period. We propose that advancing our understanding of this critical time requires more than the addition of data and will necessitate a major shift in our conceptual and theoretical framework.

Homo bodoensis and why it matters

In our original paper, we proposed a new species, Homo bodoensis, to replace the problematical taxa Homo heidelbergensis and Homo rhodesiensis, with the goal of streamlining communication about human evolution in the Chibanian. We received two independent responses. Given their substantial overlap, we provide one combined reply. In this response: (1) we are encouraged that the primary proposal in our paper, to discontinue the use of H. heidelbergensis (as a junior synonym to Homo neanderthalensis) due to its' nomenclatural problems, is acknowledged. (2) we provide additional clarification about the rules governing taxonomic nomenclature as outlined by the International Code of Zoological Nomenclature and join the growing calls for a revision to these rules. (3) we discuss further why H. rhodesiensis should be abandoned, particularly in light of the current sensitivity to using culturally inappropriate names. We conclude that H. bodoensis is a better solution than the proposed alternatives.