Some 20,000 years ago during the Last Glacial Maximum when sea levels were much lower than today, the islands of Borneo, Sumba, Sumatra were connected with the Asian mainland forming a peninsula known as Sundaland; while Australia was connected with Papua New Guinea - forming the continent of Sahul.
Between those two landmasses, there was a bunch of islands known as Wallacea, named so after the British naturalist Alfred Russel Wallace, who in 1859 described these islands as transitional ecozones between those of the former Sundaland and those of the former Sahul. When it comes to animals, west of the Wallace Line - in former Sundaland - Wallace found only organisms related to Asian species, while to the east - he found that a mix of species of Asian and Australian (Sahulian) origins is present.
Interestingly, a similar division on both sides of the Wallace Line can be seen in modern Indonesia when it comes to human genetics and ancestry, in terms of Admixture percentages. Populations living to the west of the Wallace Line harbor basically no any Oceanian (Sahul-related, Papuan-like) admixture. They mainly harbor Malayan-like admixture (which - within Indonesia - peaks in Javanese ethnic groups) as well as other types of Mongoloid (such as East Asian or South-East Asian) admixtures. On the other hand, populations living to the east of the line harbor high levels of Oceanian admixture, similar to those found in Polynesian peoples, or even higher and similar to those found in Fijians or Melanesian peoples.
A map of Indonesia - showing only noise-level Oceanian west of the line:
Brak komentarzy:
Prześlij komentarz