Exploring DNA Origins and History in the Sulu Archipelago

by Jae Joseph Russell B. Rodriguez (Ribozymes)

I have spent most of 2019 and the early months of 2020 in field expeditions in the Sulu Archipelago and Zamboanga in the southern Philippines. Together with a field team, I collected saliva samples from indigenous inhabitants to study the genetic origins and history of a unique region. Traversing the island chain through countless boat and ship voyages, I often found myself in unfamiliar territory without leaving the political boundaries of the Philippines. But I was never alone. Such an enormous task was possible with the help of locals and institutions who trusted in the value of the work we do. 

The field season culminated with a collection of more than 2,000 DNA samples from more than 100 villages spread from across Zamboanga City to Sitangkai municipality near the Malaysian border. This is to date the largest indigenous genetic sampling of a Philippine region. Through the process, I learned to speak Sinama, the language of the Sama Dilaut, more commonly known as the sea nomadic Badjao. I was immersed in cultures shaped by the region’s diverse island environments and by its complex history unfolding through the centuries. I myself was also changed by the sea-world of Sulu.

The Sulu Archipelago and immediate environs. (Google Maps 2020)

The Geographic Setting

The Sulu Archipelago is a chain of more than 800 islands connecting Zamboanga Peninsula in Mindanao and Sabah in Borneo. The outlying Mapun Island is located about 400 kilometers west of Zamboanga. The chain has been an important migration route for humans and fauna which continues to the present. Today, the archipelago is divided to the three Philippine provinces of Basilan, Sulu, and Tawi-Tawi. 

This region at the southernmost tip of the country has figured in many significant demographic and political changes in the past. Like steppingstones, the island chain was the conduit of ancient human migrations into and out of Philippines. The Sama-Bajaw languages spoken in the archipelago are thought to originate from the Barito river basin in south-eastern Borneo. With the arrival of Islam, the Sultanate of Sulu formally rose as the seat of maritime power over a region that at its maximum extent included parts of Borneo and Palawan. Sulu then was a thriving ecosystem ruled by the Tausūg elite who made subjects of the locals and slaves captured from all over the Philippines. Today, modern-day nation boundaries largely restrict freedom of movement in what used to be a larger network of coastal settlements connected by trade and kinship.

Explaining the DNA as laha’ ka’mbo’an (blood of ancestors) to the Sama Dilaut. (Photo courtesy of Atty. Gibran Abubakar)

The Peoples

The archipelago is home to various groups of Sama, who usually identify with their island origins, for example the Sama Pangutaran and Sama Bangingi’. These Sama groups show linguistic diversity and are often recognized by their unique speech characteristics. Upon gaining some grasp of the Sinama language, I noticed how the intonation and vocabulary choice among its speakers tend to vary as we moved from one island to another.

While the Sama are generally adapted to coastal living, the Sama Dilaut, literally Sama of the sea, stand out as the most maritime oriented. They used to live entirely in houseboats before the socioeconomic changes of the last half-century drove their transition to stilt-village living. They thrive by diverse ways of fishing and seafood collecting. The most adept are capable of breath-hold diving without sophisticated equipment.

The Tausūg, since the reign of the Sultanate, has been the politically dominant group. Their language is now the lingua franca of the region. Originally from Jolo Island, they now settle in most parts of the archipelago. Further north in Basilan are the Yakan, whereas Mapun Island west of Zamboanga is where the Jama Mapun reside. Both are land-dwellers with unmistakable cultural and linguistic connections to the Sama.

In common practice, field geneticists would look for sample donors who are unadmixed or of so-called “pure” ancestry.  However, we found that ethnic identities in the Sulu Archipelago are often not as neatly boxed as we wanted it to be. For example, Tausūg and Sama intermarriages are common, resulting in children who may identify as both. In Tawi-Tawi, we’ve visited entire villages historically founded by Tausūg or Bangingi’ settlers who mixed with the local Sama. A person’s ethnic identity may sometimes have little to do with ancestry. In Mapun, locals who descended from Joloanos may identify as Jama Mapun, having spent their entire lives in the island and primarily speaking Pullun Mapun. Later, we learned that “Jama” means “person” and therefore “Jama Mapun” literally means a person from Mapun. Ethnic identities should thus be interpreted with nuances of histories and etymologies.

In Mapun Island, Tawi-Tawi, our most isolated field site.

Field Research among Indigenous Communities

The initial success of the field research depended on our partnership with several institutions and local communities. As we conduct research involving human participants, we sought ethical approval from the UP Manila Research Ethics Board. Our study was authorized by agencies with the direct mandate of protecting the interests of indigenous peoples. These are the Office for Southern Communities for Tawi-Tawi and Sulu and the National Commission on Indigenous Peoples (NCIP) in Region IX for Basilan and Zamboanga City. In compliance with the NCIP Administrative Order No. 1 or the Indigenous Knowledge Systems and Practices and Customary Laws Research and Documentation Guidelines of 2012, we went through the processes of disclosure, decision making, and signing of a memorandum of agreement with each community. We also formally partnered with the Mindanao State University in Tawi-Tawi whose staff joined our field team and eagerly accompanied us to their respective home communities.  In the field, we usually proceeded first to the barangay chairperson or village elders to obtain permission to conduct sampling and interviews. Courtesy calls were also made to provincial and municipal or city government units.

Free, prior, and informed consent was obtained from the communities and the individuals. With the goal of achieving a genuinely informed consent, I explained the study in the Sinama language. When speaking to the communities I used the term, laha’ ka’mbo’an, literally meaning “blood of the ancestors” as a way of explaining the DNA in Sinama. Using this term coined by my Sama friend, Altan Ishmael, the people appreciated the DNA as a connection to their ancestors and as their inheritance from an ancient past.

In honoring the peoples’ rights over their indigenous knowledge, we made clear of our role as the custodians to their samples and that of the community as the owner. Therefore, the knowledge we get from their DNA would have to be shared to them. With the locals as the authors of their own history, we will return to the communities to seek their approval and contribution in the interpretation of the genetic results. As we also explain to them, the DNA provides only one perspective about their identity and will not replace their existing worldview.

The DNA Story

In our DNA is a story. While I have yet to proceed with the analysis, I surmise that the DNA story of the Sulu Archipelago will reverberate the broader generalizations about our history as a species. First, this story will likely retell of how human populations have always mixed. We now know that Homo sapiens mixed with at least two archaic humans, the Neandertals and the Denisovans. Earlier genetic studies on Filipinos revealed that we are largely descended from Austronesian speaking farmers who mixed with local hunter-gatherers long before established in the Philippine archipelago. It is very likely, for example, to find evidence for the mixing of Sama and Tausūg ancestors who for centuries coexisted in the Sulu Archipelago. It will also not be surprising to perhaps discover the genetic legacies of captive slaves and Arab missionaries integrating into the melting pot that was the Sultanate of Sulu.

The DNA narrative will also be a human success story. Through the history of the spread of our species, our ancestors conquered diverse terrain and climates, were constantly exposed to new pathogens, and faced novel dangers in Africa and beyond. We know that all our ancestors lived long enough to survive those challenges, for here we are, their living descendants. The Sama Dilaut, who have most successfully conquered the marine environment, will likely possess genomes revealing their adaptations to such a unique human niche.

Lastly, it will be a story about a shared identity. Geographic distance and long-standing politico-ideological conflicts have largely alienated the region. But as the Sulu Sea is contiguous with more northernly waters, the genomes of the inhabitants of the archipelago will almost certainly point to their broader connections to the rest of the Philippines. The DNA, the thread that connects us all, will add to the narrative of the Sulu people’s complex history and identity. This narrative is indeed part of our own story too as Filipinos.

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Jae Joseph Russell B. Rodriguez is an Assistant Professor and has taught genetics and evolution at the Genetics and Molecular Biology Division in the Institute of Biological Sciences, UPLB. Since 2012, he has been collaborating with the DNA Analysis Laboratory at the Natural Sciences Research Institute, UP Diliman on forensic genetic and population genetic research. He is currently a PhD student at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.