Pre-Clovis: mtDNA B4b1 ubiquitous presence among four Filipino negrito populations in Luzon.

Gisele Horvat writes:

In Heyer et al’s “Genetic Diversity of Four Filipino Negrito Populations from Luzon: Comparison of Male and Female Effective Population Sizes and Differential Integration of Immigrants into Aeta and Agta Communities”, I am surprised to see haplogroup B4b1 singled out. mtDNA sequences belonging to this group are the Asian/Oceanic ones which are phylognetically closest to the Native American B group (“B2”). In fact, the Native American ones could have been called B4b1 and the Asian/Oceanic B4b2.

See the B4b group here:

http://www.phylotree.org/tree/subtree_R.htm

I’ve previously noticed that the Aboriginal Taiwanese Bunun had a high frequency of B4b1 lineages as well as Hainan Islanders.

From Heyer et al:

“The two most common mtDNA haplogroups, B4b1 and P9, are present in all four negrito populations and constitute 45% of all lineages found. P9 (previously called P8) has been found at very low frequency among the general population of Luzon and Visaya provinces, and together with P10, these have been proposed as autochthonous lineages (Tabbada et al. 2010). B4b1 overall represents more than 20% of the negrito maternal lineages, compared with approximately 7% of the general population of the Philippines.”

“The mtDNA haplogroups B4b1, B5b, E1b1, F1a3, F1a4, and R9* constitute ~33–57% of the Agta and Aeta maternal lineages but are not unique to the Philippines and are considered to have distributions arising prior to the dispersal of Austronesian speakers from Taiwan (Hill et al. 2007; Tabbada et al. 2010). Of these, B4b1 merits particular attention because of its ubiquitous presence among the four negrito populations, across the East Asian mainland and Japan (Trejaut et al. 2005). The relative prevalence of B4b1 among the negritos of Luzon suggests a presence in the Philippines prior to the Austronesian expansion approximately 4–6 kya, which could also predate the long-term separation of the Aeta and Agta indicated by the differentiation in autosomal genetic diversity.”

Gisele

Genetic Diversity of Four Filipino Negrito Populations from Luzon: Comparison of Male and Female Effective Population Sizes and Differential Integration of Immigrants into Aeta and Agta Communities

Abstract

Genetic data corresponding to four negrito populations (two Aeta and two Agta; n = 120) from the

region of the Philippines have been analyzed. These data comprise mitochondrial DNA (mtDNA)
hypervariable segment 1 haplotypes and haplogroups, Y-chromosome haplogroups and short
tandem repeats (STRs), autosomal STRs, and X-chromosome STRs. The genetic diversity and
structure of the populations were investigated at a local, regional, and interregional level. We
found a high level of autosomal differentiation, combined with no significant reduction in diversity,
consistent with long-term settlement of the Luzon region by the ancestors of the Agta and Aeta
followed by reduced gene flow between these two ethnolinguistic groups. Collectively, the Aeta
have a much higher ratio of female:male effective population size than do the Agta, a finding that
supports phylogenetic analysis of their mtDNA and Y-chromosome haplogroups, which suggests
different genetic sex-biased contributions from putative Austronesian source populations. We
propose that factors of social organization that led to the reduction in Agta female effective
population size may also be linked to the limited incorporation of female lineages associated with the
spopulation size, relative to females, could be indicative of a limited incorpotlement of the Philippines by Austronesian speakers; conversely, the reduction in Aeta male effective population size than do the Agta, a finding that supports phylogenetic analysis of their mtDNA and Y-chromosome haplogroups, which suggests different genetic sex-biased contributions from putative Austronesian source populations. We propose that factors of social organization that led to the reduction in Agta female effective population size may also be linked to the limited incorporation of female lineages associated with the settlement of the Philippines by Austronesian speakers; conversely, the reduction in Aeta male effective population size, relative to females, could be indicative of a limited incorporation of male lineages associated with this demographic process.

Heyer, E; Georges, M; Pachner, M; and Endicott, P (2013) "Genetic Diversity of Four Filipino Negrito Populations from Luzon: Comparison of Male and Female Effective Population Sizes and Differential Integration of Immigrants into Aeta and Agta Communities," Human Biology: Vol. 85: Iss. 1, Article 9.

http://digitalcommons.wayne.edu/humbiol/vol85/iss1/9

Aeta woman