2.3 Genetic Evidence for a Lapita Homeland in Wallacea
25
back to the late Pleistocene. These maternal lines do not possess the later mutations which occurred in Wallacea and which genetically separate populations in
the Spice Islands, coastal Papuans and Polynesians from indigenous Taiwanese and
populations in Luzon and the Philippines.
Linguistic diversity can be a pointer to linguistic origins, and claimants of the Out
of Taiwan theory have claimed an origin for the Austronesian languages in Taiwan.
But isolation can lead to both linguistic and genetic differentiations and in Taiwan
we have circumstances explaining both. Genetic differentiation through isolation
explains why the nine indigenous Taiwanese tribes are closer through their founding haplogroup B4a1a to populations in Luzon, the Philippines, the Spice Islands
and Indonesia than they are to one another. Linguistic isolation accounts for the
fact that not only are their nine languages distinct from one another but they are
also distinct from the tenth Austronesian language spoken by all other Austronesian
speakers.
Three defining mutations carried by Spice Islanders, coastal Papuans and
Polynesians but not by indigenous Taiwanese and populations in Luzon and the
Philippines, then, appear to have occurred in Wallacea in the late Pleistocene or
early Holocene. The fourth polymorphism that defines the Polynesian motif dated
variously between 10,000 and 17,000 years ago, a second mitochondrial mutation
np 14022 which Trejaut et al. show differentiates the B4a1a1 haplogroup from the
earlier B4a1a haplogroup, with a coalescence estimate from 6,800 to 11,500 years,
and the Y chromosome mutation M38 dated to about 11,500 years ago. Genetic
interactions between male traders and women from other populations would not
have affected the mtDNA of those populations but would leave a record in the Y
chromosome genes of those populations. That M38 has left no mark on populations
in Luzon, the Philippines and Taiwan means that, based on the genetic data for all
three mutations, possibly the estimate of 11,500 years for M38 might be a reasonable estimate for the last genetic interchange of these populations with Wallacea.
The estimate for M38 also fits with the chronological bounds for the mitochondrial mutations. That is to say, it might be a reasonable estimate for the last genetic
interchange which can be recognized from all-male and all-female lines in current
populations in these areas. Stretching back to the late Pleistocene or early Holocene,
these combined estimates predate by 8,000 years the estimated dates for the Express
Train to Polynesia and probably also predate those for the Slow Boat to Polynesia.
But they support the case for an ancient indigenous Lapita and Polynesian homeland
in Wallacea.
We suggest that ancient migrations need to be viewed in light of the oceanographic history of the West Pacific Warm Pool and its role in shaping Spice Island
trade and migration paths. They also need to be viewed in the context of the cataclysmic reshaping of lands bordering the West Pacific Warm Pool by rising sea
levels between 13,500 and 7,500 years ago. The drowning of vast stretches of former
continental shelf along the coast of mainland China and the drowning of the ancient
continent of Sundaland provide a vital background for understanding the genetic
and trading history of Island Southeast Asia and the record of ancient migrations
implicit in the genes of modern populations in the region.
25
back to the late Pleistocene. These maternal lines do not possess the later mutations which occurred in Wallacea and which genetically separate populations in
the Spice Islands, coastal Papuans and Polynesians from indigenous Taiwanese and
populations in Luzon and the Philippines.
Linguistic diversity can be a pointer to linguistic origins, and claimants of the Out
of Taiwan theory have claimed an origin for the Austronesian languages in Taiwan.
But isolation can lead to both linguistic and genetic differentiations and in Taiwan
we have circumstances explaining both. Genetic differentiation through isolation
explains why the nine indigenous Taiwanese tribes are closer through their founding haplogroup B4a1a to populations in Luzon, the Philippines, the Spice Islands
and Indonesia than they are to one another. Linguistic isolation accounts for the
fact that not only are their nine languages distinct from one another but they are
also distinct from the tenth Austronesian language spoken by all other Austronesian
speakers.
Three defining mutations carried by Spice Islanders, coastal Papuans and
Polynesians but not by indigenous Taiwanese and populations in Luzon and the
Philippines, then, appear to have occurred in Wallacea in the late Pleistocene or
early Holocene. The fourth polymorphism that defines the Polynesian motif dated
variously between 10,000 and 17,000 years ago, a second mitochondrial mutation
np 14022 which Trejaut et al. show differentiates the B4a1a1 haplogroup from the
earlier B4a1a haplogroup, with a coalescence estimate from 6,800 to 11,500 years,
and the Y chromosome mutation M38 dated to about 11,500 years ago. Genetic
interactions between male traders and women from other populations would not
have affected the mtDNA of those populations but would leave a record in the Y
chromosome genes of those populations. That M38 has left no mark on populations
in Luzon, the Philippines and Taiwan means that, based on the genetic data for all
three mutations, possibly the estimate of 11,500 years for M38 might be a reasonable estimate for the last genetic interchange of these populations with Wallacea.
The estimate for M38 also fits with the chronological bounds for the mitochondrial mutations. That is to say, it might be a reasonable estimate for the last genetic
interchange which can be recognized from all-male and all-female lines in current
populations in these areas. Stretching back to the late Pleistocene or early Holocene,
these combined estimates predate by 8,000 years the estimated dates for the Express
Train to Polynesia and probably also predate those for the Slow Boat to Polynesia.
But they support the case for an ancient indigenous Lapita and Polynesian homeland
in Wallacea.
We suggest that ancient migrations need to be viewed in light of the oceanographic history of the West Pacific Warm Pool and its role in shaping Spice Island
trade and migration paths. They also need to be viewed in the context of the cataclysmic reshaping of lands bordering the West Pacific Warm Pool by rising sea
levels between 13,500 and 7,500 years ago. The drowning of vast stretches of former
continental shelf along the coast of mainland China and the drowning of the ancient
continent of Sundaland provide a vital background for understanding the genetic
and trading history of Island Southeast Asia and the record of ancient migrations
implicit in the genes of modern populations in the region.