Open Access Preprint
A number of recent articles have appeared on the hominin Denisova fossil remains. Many of them focus on attempts to produce DNA sequences from the extracted samples. Often these project mtDNA sequences from the fossil remains of a number of Neandertal fossils and the Denisovans in an attempt to understand the evolution of Mid Pleistocene human ancestors. These papers, introduce a number of problems in the interpretation of speciation in hominins. One concerns the degradation of the ancient DNA and its interpretation as authentic genetic information. Another concerns the idea of “species” versus that of “population” and the use of these ideas in the building of evolutionary diagrams to indicate ancestry and extinction. Since I have dealt with the issue of degradation elsewhere (Caldararo,2016) I will limit this paper to ideas of probability, phylogenetics, species and population. A third issue concerns the theory of haplotypes in the mtDNA. Given the severe constraints on mutations in the mtDNA genome to maintain functionality and the purifying processes to reduce such mutations in the ovaries, putative geographic and historical variations seem contradictory. Local diversity and variations in supposed “macrohaplotypes” are explained as back migrations or back mutations which dilutes the robust nature of the theory. A central issue is what does human variation mean, how much population variation has there been in the past and how does this variation distinguish hominid speciation or simply a process of anagenesis. Some businesses today claim to be able to use DNA analysis to discover past ethnic identities and a new niche in restaurants is producing “DNA” menus. Perhaps some caution is in order.
Caldararo, Niccolo, "Probability, Populations, Phylogenetics and Hominin Speciation" (2019). Human Biology Open Access Pre-Prints. 144.