Three High Profile Genus Homo Discoveries in the Early 21&lt;sup&gt;st&lt;/sup&gt; Century and the Continuing Complexities of Species Designation: A Review—Part I

Conrad B Quintyn

doi:10.13189/sa.2019.070605

Abstract

Human paleontologists are unable to extricate species-level variation from individual, sexual, regional, geographical, pathological, and skull bone variations despite sophisticated statistical methodology. Additionally, true variation within and between groups cannot be generated from a handful of regional and geographical specimens presently used in comparative studies. I therefore conclude that we cannot identify species in the human paleontological record. This conclusion is supported by the analysis and discussion (in this paper) of research conducted on, what I deem to be, three high-profile genus Homo fossil discoveries: Dmanisi hominins, Homo floresiensis, and Homo naledi. The data compiled in these comprehensive studies conclude that Dmanisi, floresiensis, and naledi share features with all Homo and Australopithecine taxa. Specifically, none of these three fossils clustered or aligned definitively with any Homo specimens. Consequently, it may now be prudent for us to use numbers or look for gross similarities and differences in hominin fossils to classify them. As such, identifying fossils at the genus level, which was proposed recently, might be a solution worth considering. Using genera will reduce the specificity needed in species identification, but it might be preferable to the chaos we have now in species-level identification. This paper is published in two parts.

Highlights

In part 1 of this paper, I discuss the Dmanisi hominins
In part 2, published in a separate issue, I complete the paper with a discussion of Homo floresiensis, Homo naledi, and possible solutions to this complex problem
In 2009, I wrote a paper on the excessive naming of new hominin species in the fossil record

Summary

Introduction

In part 1 of this paper, I discuss the Dmanisi hominins. In part 2, published in a separate issue, I complete the paper with a discussion of Homo floresiensis, Homo naledi, and possible solutions to this complex problem. Researchers use geometric morphometrics (Procrustes distances) to write about the tremendous overlap in inter- and intra-group variability in skull diversity in the genus Homo: “The range of inter-group distances calculated between H. naledi and H. erectus in this analysis is larger than the distances between P. troglodytes and H. sapiens, which may indicate that either the H. erectus sample has a large degree of intra-group variability or that this variability may be inter-specific” [11] In another example, researchers analyzing shape variables from Dmanisi and other Homo specimens emphasize taxonomic problems: “Analysis based on shape variables obtained from the dental arcade places KNM-ER 60000 closer to D2600 and other specimens from Dmanisi than to KNM-ER 1482, raising a question as to whether KNM-ER 60000 might represent H. erectus. Mating does not equal fertility, and fertile hybrids complicate the picture

Skull asymmetryc

Findings

General Statements