Unraveling millennia of human migration to the Philippines

With its abundance of shorelines, the Philippine archipelago has long been theorized to have been traversed by early humans through land bridges or early seacraft such as the balanghai. This theory, known as Wave Migration, was first proposed by American anthropologist H. Otley Beyer but was later discredited due to a lack of archaeological evidence. Soon after, modern theories such as the Out-of-Sundaland and Out-of-Taiwan emerged to better investigate the prehistoric habitation of the Philippines, particularly by those of Austronesian descent.

With slightly inconsistent details, supporters of the Out-of-Sundaland claim that Austronesian peoples came from the now recessed Sundaland landmass, which encompassed modern Sumatra, Java, Borneo, and Malay Peninsula. Meanwhile, Peter Bellwood, proponent of Out-of-Taiwan, argues that the first Austronesians left Taiwan and entered the Philippines at around 2200 BC. These peoples were discovered to have resided in northern Luzon, specifically in the islands of Batanes.

Of the two models, the Out-of-Taiwan model, however, is more widely recognized due to its further linguistic, archaeological, cultural, and genetic support. While both theories are currently deemed justifiable, a recent study from Uppsala University reveals findings that are inconsistent with either model.

The study also explores the minimal genetic legacy of Spanish colonization in the Philippines, the least admixture of the Cordilleran group, and the emergence of cereal agriculture in the Philippines. Maximilian Larena, one of the authors of the study, entitled Multiple migrations to the Philippines during the last 50,000 years, explains the methods and findings of the paper.

The study features the analysis of broad population-genomic data, covering 1,028 individuals from 115 indigenous groups. Single Nucleotide Polymorphisms (SNPs), a type of genetic variation, were also identified among the tested individuals. An SNP is a change in a single nucleotide—the basic building blocks of DNA—at a specific position of the genome. These changes can be prompted by random mutations and can also be passed from one generation to the next.

Larena elaborates that the patterns and frequency of these changes can be used in investigating genetic variation within and between populations. In their study, massive amounts of data were acquired from observed patterns of genetic variation in both individuals and populations. The study then proceeded with a systematic analysis of the obtained data to make inferences about the demographic past. These inferences may estimate a certain population’s structure, size, diversity, and even accounts of admixture or interbreeding between groups of people.

At the end of the most recent ice age, newly-risen seas restricted the amount of inhabitable land, and some landmasses were even split into multiple islands. Larena clarifies that there were at least five waves of modern human migration into the Philippines. The first two, the Southern and Northern Negritos, entered the archipelago around 40 to 50,000 years ago. They were discovered to be genetically related with Australian Aborigines and Papuans and were also regarded as the “First Filipinos”.

Succeeding the migration of the First Filipinos was that of Manobo-related and Sama-related groups. Ancestral Manobos and Samas emerged fifteen and twelve thousand years ago, respectively. Both entrances, Larena adds, occurred at a time when climatic events brought significant changes to Sundaland’s landscape.

Lastly, the Cordillerans were approximated to have arrived seven to ten thousand years ago. This event was also preceded by the separation of the group from the indigenous Taiwanese, such as the Amis, Atayal, and Paiwan. Similar to the third and fourth wave, the fifth wave simultaneously arose with climate-induced geographical changes but in the South China-Taiwan greater area.

The exact reasons why the Cordillerans had the least amount of genetic admixture are yet to be determined. “We may never know for real, given that it is very difficult to formally test the various hypotheses,” Larena admits.

However, it can be surmised that this phenomenon is attributed to geographical isolation and cultural reasons. This geographical isolation may stem from the Cordillerans’ preference to reside away from coastal areas. They, unlike other ethnic groups, lived across landlocked mountain ranges in the north of Luzon. Cultural reasons, Larena adds, may involve linguistic and customary practices, which may hinder intermarriages between different ethnic groups.

One of the notable findings in the study is the role of Northeast Asian (nEA) ancestry in the development of rice agriculture. nEA ancestry, Larena defines, is “a genetic component which is found in high proportions among China’s northern Han and Far-East Russia’s Siberian-related communities.” Archaeological proof conveys that the domestication of the cereal crop began around eight to ten thousand years ago along Northern China’s Yellow River.

In addition, the rice variant Oryza japonica was domesticated roughly eight thousand years ago along the Yangtze River. Relating these with ancient DNA data, it has been discovered that inhabitants of Northern East Asia already possess high levels of nEA ancestry. These data may also suggest that increased proportions of nEA ancestry are likely to be discovered among the East Asians who have initiated cereal domestication. However, Larena acknowledges that strong archaeological support has yet to be established to prove this hypothesis.

In addition, the researchers posit that cereal agriculture was advanced by these populations with nEA ancestry who have migrated southward into coastal Southern China and into Taiwan. However, there is only a minimal nEA genetic signal among a number of Filipino coastal communities. Similar to the former, its association with the spread of farming remains a speculation until further investigation.

Ultimately, there is still much to be discovered in the lives of early Filipinos and only time will tell the hidden stories embedded within their lost culture.