paper: unexpected NRY chromosome variation in Melanesia

Unexpected NRY chromosome variation in Northern Island Melanesia
Scheinfeldt et al
Molecular Biology and Evolution, Advance Access

To investigate the paternal population history of populations in Northern Island Melanesia, 685 paternally unrelated males from 36 populations in this region and New Guinea were analyzed at 14 regionally informative binary markers and seven short-tandem-repeat loci from the non-recombining portion of the Y chromosome. Three newly defined binary markers (K6-P79, K7-P117, and M2-P87) aided in identifying considerable heterozygosity that would have otherwise gone undetected. Judging from their geographic distributions and network analyses of their associated short-tandem-repeat profiles, four lineages appear to have developed in this region and to be of considerable age: K6-P79, K7-P117, M2-P87, and M2a-P22. The origins of K5-M230 and M-M4 are also confirmed as being located further west, probably in New Guinea. In the 25 adequately sampled populations, the number of different haplogroups ranged from two in the single most isolated group (the Aita of Bougainville), to nine, and measures of molecular diversity were generally not particularly low. The resulting pattern contradicts earlier findings that suggested far lower male-mediated diversity and gene exchange rates in the region. However, these earlier studies had not included the newly defined haplogroups. We could only identify a very weak signal of recent male Southeast Asian genetic influence (<10%), which was almost entirely restricted to Austronesian (Oceanic) speaking groups. This contradicts earlier assumptions on the ancestral composition of these groups and requires a revision of hypotheses concerning the settlement of the islands of the central Pacific, which commenced from this region.

Have yet to digest this and its implications, will read it today and update. The emphasis is mine, as it is the intriguing part.


2 responses to “paper: unexpected NRY chromosome variation in Melanesia

  1. [response to deleted comment]

    The whole concept of Melanesian is so problematic when you’re trying to fit together different bits of evidence from genes/languages/archaeology etc. I’m not quite certain which migration hypothesis you feel needs revising–like all science, they’re ALL pretty much under revision as new data come to light anyhow.

    I’ve just read this paper the once and haven’t gone back to it yet. But to try and address your questions: A low percentage of SEA Y markers in Island Melanesia doesn’t contradict the hypothesis that the Austronesian-speaking peoples originated from SEA; it just says that the non-Austronesian (Papuan, if you like) groups had a significant intermixing time with those earlier-arrived populations. Also, the Y tracks the movement of men, so this just says that the SEA markers are not so apparent in male-specific lineages, which, if the Proto-Oceanic populations were matrilineal /matrilocal as some have suggested, we would expect to see.

    Also, they don’t address directly the questions pertaining to Polynesians, who do have (at least in mit DNA, the female-specific marker) a fairly obvious SEA component. It’s clearly neither one nor the other: people will always intermarry and we’re talking about a timespan of thousands of years. There’s been a great deal of genetic anthropology of Pacific peoples done in the last few years. If you have access to something like the Web of Science database a quick keyword search will bring up dozens of papers.

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