Probability, Populations, Phylogenetics, and Hominin Speciation.

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 mitochondrial DNA (mtDNA) sequences from the fossils of a number of Neandertals and the Denisovans in an attempt to understand the evolution of Middle Pleistocene human ancestors. These articles 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 problem concerns the ideas of "species" versus "population" and the use of these ideas in building evolutionary diagrams to indicate ancestry and extinction. 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 involves what human variation means, how much population variation there has been in the past, and whether this variation distinguishes hominid speciation or is simply a process of anagenesis. This brings up the question of how much can be interpreted from the analysis of DNA. 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.

Denisovans, Melanesians, Europeans, and Neandertals: The Confusion of DNA Assumptions and the Biological Species Concept.

A number of recent articles have appeared on the Denisova fossil remains and attempts to produce DNA sequences from them. One of these recently appeared in Science by Vernot et al. (Science 352:235-239, 2016). We would like to advance an alternative interpretation of the data presented. One concerns the problem of contamination/degradation of the determined DNA sequenced. Just as the publication of the first Neandertal sequence included an interpretation that argued that Neandertals had not contributed any genes to modern humans, the Denisovan interpretation has considerable influence on ideas regarding human evolution. The new papers, however, confuse established ideas concerning the nature of species, as well as the use of terms like premodern, Archaic Homo, and Homo heidelbergensis. Examination of these problems presents a solution by means of reinterpreting the results. Given the claims for gene transfer among a number of Mid Pleistocene hominids, it may be time to reexamine the idea of anagenesis in hominid evolution.

The Maori, behavior, modern diets and colorectal cancers.

Variation in diet and the rates of colorectal cancers have confounded researchers in recent years. Comparisons of populations in different geographic locations and of different ethnic origins have shown considerable differences in disease frequency, location and relation to diet. This paper revisits an earlier comparison of Maori rates of disease and diet based on data from 20 years ago with surprising changes in disease rates today.

Analysis of pesticide residues on museum objects repatriated to the Hupa tribe of California.

In the past, it was common practice for museum professionals and private collectors to apply a variety of pesticide agents to objects in their collections to preserve them from depredations by microorganisms, fungi, and other pests. The Native American Graves Repatriation and Protection Act allows federally recognized tribes to request that museums return objects taken from their ancestors. Given that poor records were kept on the treatment of individual objects, it is unknown whether specific objects are contaminated with these pesticide agents. Although chemical analysis represents the only reliable means to determine the types and levels of pesticides on these objects, surprisingly few publications document the extent of this contamination in museum collections. This paper reports on the determination of arsenic, mercury, and several organic pesticides on 17 objects that were recently repatriated to the Hupa tribe in northern California. Four samples were taken from each object: two for arsenic and mercury analysis via flame atomic absorption spectrophotometry and two for organic pesticide analysis via gas chromatography/mass spectrometry. Percent levels (wt/wt) of mercury were detected on many samples, and 0.001 to 0.183% (wt/wt) levels of p-dichlorobenzene, naphthalene, thymol, lindane, and/or DDT were detected on many of the samples. These results indicate that Hupa tribal members should not wear these objects in religious ceremonies, proper precautions should be followed when dealing with potentially contaminated objects, and that more serious consideration should be given to this issue at a national level.