February 12, 2009

Bacteria and the human peopling of the Pacific

A new paper in Science looks at the peopling of the Pacific from the perspective of genetic diversity of the bacterium H. pylori which is found in people's stomachs.

Related to: Bayesian phylogenetics of languages and the timing of Austronesian settlement of the Pacific from Taiwan

Science doi:10.1126/science.1166083

The Peopling of the Pacific from a Bacterial Perspective

Yoshan Moodley et al.


Two prehistoric migrations peopled the Pacific. One reached New Guinea and Australia, and a second, more recent, migration extended through Melanesia and from there to the Polynesian islands. These migrations were accompanied by two distinct populations of the specific human pathogen Helicobacter pylori, called hpSahul and hspMaori, respectively. hpSahul split from Asian populations of H. pylori 31,000 to 37,000 years ago, in concordance with archaeological history. The hpSahul populations in New Guinea and Australia have diverged sufficiently to indicate that they have remained isolated for the past 23,000 to 32,000 years. The second human expansion from Taiwan 5000 years ago dispersed one of several subgroups of the Austronesian language family along with one of several hspMaori clades into Melanesia and Polynesia, where both language and parasite have continued to diverge.



pconroy said...

Fascinating, so where would the Austronesian natives of Madagascar be on the chart?

Where are Europeans on the chart?

Why is the divergence of the hpSahul so late? I thought this area was supposed to be inhabited by 60K BP - or is this a confirmation that the Mungo Man find was correct, and earliest Australians were replaced by current Aborigines??

Maju said...

Hm... if node 2 is calibrated to c. 40,000 years ago, how come did you place the Asia-Australia node at 32-33 Kyr? Shouldn't it be more like 45-50 Kyr?

Sand, Wind & Stars said...

Just out of curiousity as I'm not an academic nor scholarly, where does that leave that big blob called the Philippines? (Lots of yellow dots).

I gathered that the one group of Austronesians, and one language branch migrated to the Philippines, from there branched out into south east (all the way to Madagascar) and west migration as far Easter island and New Zealand.

As far as the dark skinned, frizzy haired Filipinos, I understand they are non-Austronesians but came from the same branch as Papuans, Melanesians and Australian aborigines.

Maju said...

I think that the authors of that other study mean that Philippines was only colonized in a second moment but not from Indonesia but by a local expansion of Filipino Austronesians. It's anyhow a linguistic tree, so it's not solid like engineering but a more or less insightful reconstruction.

Negritos (Spanish for "Little Blacks") are a varied array of aboriginal people of peninsular Malaysia and island SE Asia, normally showing short height and some less important African-like (or rather Melanesian-like) traits like frizzy hair and the usual dark skin of tropical peoples with very deep roots. They don't seem specially related to Papuans or Melanesians but rather would seem other pockets of very ancient human colonization of the area.