The Origin of Indonesian Humans
Have you ever question your origin?
We hear stories from parents, grandparents, and great-grandparents about the places they lived in during their life. Where they were born, married, and migrated. These events explain why we are here. Their stories shape our personal history and ultimately, our identity.
However, have we ever asked whether we all share a similar story to cement our identity of being the Indonesian people?
To answer this question we must travel the past and see what happened then.
Of course, we don’t have a. real “time-machine” that can actually take us physically back in time. But scientists can help us. We can count on them to at least catch what happened and to see who are the inhabitants of the Archipelago in the far past. By researching the present, they could explore the past. Fossils, artifacts, language, and the composition of genes in our bodies. All are clues they use to look far back in time, long before our great-grandparents grace the earth.
A number of studies in the fields of physical anthropology, archaeology, and linguistics suggest that humans entered our archipelago in two great waves. But studies on population genetics, which began in the 2000s, found there were at least 4 waves of human migration underlying the diversity of Indonesian people today. The latest research in the field of archaeo-genetics, a research-field that analyses genetics of human fossils, says that the Indonesian nation has been diverse since the Pleistocene (that is about 50,000 years ago).
Understanding these clues is like tying puzzle pieces in a detective investigation. It is not uncommon for one clue to refute another. The clashes are about putting the right pieces in the right place until a full picture emerges.
Therefore, please fasten the seat belts because we’re about to venture into the past!
Time machine: physical anthropology, archeology and linguistics.
The journey to find the origin of Indonesian people began in 1945, the year the Indonesian republic was born. At that time, the Austrian anthropologist and ethnologist Robert von Heine-Geldern saw a similarity between stone tools artifacts found in Indonesia and those in mainland Southeast Asia. He then concluded that the ancestors of the Indonesian people were Austronesian-speaking people who came from the Yunnan mainland in South China. Heine-Geldern argues that the ancestors of the Indonesian people migrated in two waves, each during the Neolithic period (2,000 BC) and during the Bronze-Iron period (500 BC). This theory remains on school textbooks until today.
Pieter Vincent van Stein Callenfels, a Dutch prehistoric expert and archaeologist in Batavia (with collection currently stored at Jakarta National Museum), begged to differ. He thought when the Austronesians moved to the Archipelago 4,000 years ago, the territory was already inhabited by indigenous people who are often referred to as Australo-Melanesian and had been inhabitants of the archipelago since 40,000 years ago.
In contrast to appearance, the Austronesian was widely characterized as brown-skinned, whilst the Australo-Melanesians have darker skin and are curly haired. The Austronesian-speaking population, with its agricultural technology dominated the western part of Indonesia, and blended to the Australo-Melanesian group. The result of this admixed populations is the Senoi in the Malay Peninsula or Sakai/Kubu in Riau, and Batak and Mentawai in North Sumatra. Meanwhile, the Australo-Melanesian population who migrated to Eastern Indonesia became the ancestors of the Papuans and the adjacent smaller islands. This is called the Two-Layers Hypothesis.
But this is not the only hypothesis that exists. It cannot be science if a hypothesis cannot be tested and criticized.
In the early 1990s, Christy G Turner II, an anthropologist from the University of Arizona in the United States, found differences in the character of the teeth in mainland and islands Southeast Asian populations, including the population of Indonesia. He classified his findings into two groups: the Sundadonty and Sinodonty. Turner saw that the 'Sundadont' tooth arrangement, which was scattered in a population characterised by Australo-Melanesia, was still present in the descendants of the Southeast Asian population. This refutes the previous theory that the ancestors of today's Southeast Asia were from Yunnan, because if so, the character of the teeth should be Sinodonty. This theory became known as Regional Continuity or Local Evolution.
At about the same time, archaeologist Peter Bellwood of the Australian National University, collaborated with linguist Robert Blust from the University of Hawai'i to research the origin of humans in the Southeast Asian Islands through comparative linguistic studies. They put forward a theory that places Taiwan as the land of origin of the proto-Austronesian language.
Based on that study, Blust proposes that Austronesian geographic expansion started inTaiwan, as the location for the oldest Austronesian languages, including proto-Austronesian, then spreading it to the Philippines, Borneo and Sulawesi, and finally this wave separated: one branch spreads to the West (Java), another to the East (Oceania) via the Bismarck Archipelago.
The language reconstruction is based on vocabulary related to numbers 1-10, tools used for fishing, food crops, livestock, and things related to daily life. This supports the theory of the migration process from Taiwan during the last 4,000 years (out of Taiwan), giving a new life to the reappointment of the Two-Layer Hypothesis.
Modern Genetic Breakthroughs
The debate of archaeologists, linguists, and anthropologists is still ongoing at a time when modern genetic science was developing rapidly. Apparently, it's not just fossils, language, and stone tools artifacts that can take us back in time. DNA, the arrangement of nitrogenous bases that spiral through our bodies, also has the ability to tell us what happened in the past. Therefore, in the last decade, population genetics research has tried to contribute to the history of the origins of Indonesian humans, after previously being dominated by narratives based on physical anthropology and archaeology-linguistics.
Genetic research in Southeast Asia only developed after the Pan-Asian HUGO Consortium (2009) succeeded in analyzing the genome of Southeast Asian societies. This research shows that the genetic component is related to ethno-linguistic groups. For example, about 50% of the East Asian genetic component can be found in the Southeast Asian populations. The genetic components that dominate the Aboriginal Taiwanese (Ami and Atayal) are also found to dominate Nias and Mentawai, where both tribes have similar language structures. This has inspired a more in-depth study of population genetics in Indonesia and Southeast Asia.
In 2010, Tatiana M Karafet, a geneticist from the University of Arizona, collaborated with Herawati Sudoyo, a molecular biologist at the Eijkman Institute in Jakarta to compile the genetic history of the Indonesian population based on paternal lineages by examining the genes from the Y-chromosome which are only inherited from father to a son. She then identified a number of haplogroups, kinship relationships based on similar mutation patterns of Y-chromosomes.
Haplogroup can be used to trace kinship (paternal/maternal) because these genetic markers do not undergo recombination when there is a mixing between populations.
For example, a male today will have as many Y-chromosome mutations similar to their ancestors who lived 100-200 generations ago. The farther in the past, the fewer mutations similarly to the ancestors, but the kinship relations still exist in a paternal lineage. (For example, a man with haplogroup O1a-M119 would have the same mutation as a Liangdao human who lived 8300 years ago. The relation: shared a common ancestor who probably lived more than 10,000 years ago in Southern China).
Karafet found that there were at least four waves of modern human migration in Indonesia (Homo sapiens).
- The first wave is assumed to have occurred about 45,000 years ago based on the distribution of the paternal lineages of the haplogroup C-RPS4Y and K2-M526, characterising the paternal line of the Australo-Melanesian populations, the ancestors of the Papuan people.
- The second wave occurred in the Ice Age (from 35,000 to 8,000 years ago) where there was a migration of hunter-gatherers from mainland Southeast Asia, carrying the paternal basal haplogroup O (O1a and O1b). This assumption is influenced by the similarity of the Hoabinhian and sumatralith stone tools.
- The third wave was marked by the expansion of Austronesian speakers from 5,500-4,000 years ago, spreading the paternal haplogroup O1a1-P203 and O1a2-M110.
- The last wave occurred in the last 2,500 years, marked by the entry of paternal lineages from India and the Middle East (along with the spread of Hinduism and Islam), and European colonialists in the last 500 years, which drained the natural wealth of the archipelago.
This scenario is also supported by research that analyses the history of human migration in Indonesia through the maternal line. In 2013, Meryanne Kustina Tumonggor, a researcher at the Eijkman Institute who was a doctoral student at the University of Arizona, examined the composition of mitochondrial DNA that is inherited through the maternal lineages (from mother to children, both male and female). In general, the results suggest a similar scenario with paternal lineage migration.
Archaeogenetics: The Stories From The Dead
It turns out that the scenario of four waves of migration to Indonesia has yet to be tested. But science continues to move forward. In 2018, scientists began to look further into the past by analyzing the DNA of people who died thousands of years ago. The study looked at the traces of the early human existence in Sumatra, Borneo, Java, Sulawesi, Nusa Tenggara, Papua New Guinea and Australia, before 50,000 years ago. Unlike the previous methods, the time frame emphasizes a period that cannot yet be reached by physical and linguistic anthropology research.
From 2010-2019, scientists began analyzing Denisovan fossils, an ancient human species found in the Altai mountain of Siberia. The result indicated that a portion of the Denisovan gene was found in most of the genomes of present-day Papuans. Further analysis showed that about 46,000 years ago the Australo-Melanesian and Negrito Philippine ancestors encountered the southern Denisovan in the Sunda (most likely in the form of Homo soloensis).
In 2018, Hugh McColl, a geneticist and bioinformatics expert from the Natural History Museum of Denmark, with several colleagues studied the ancient genome of DNA from the bones of hunter-gatherers who died 4,000-8,000 years ago in southern China and Vietnam. The team also analysed the DNA from bones of early farmers from mainland and archipelago Southeast Asia of 500-4,000 years ago.
McColl's research is an eye opener. He pointed out that 50,000 years ago, it was not only the Australo-Melanesian ancestors who inhabited the archipelago, but also the ancestors of the Andaman islanders, the Hoabinhian hunters in mainland Southeast Asia, the Orang Asli Semang in the Malay Peninsula, Aeta, Agta and Ati Negritos in Philippines. They all belong to the same group, the basal southern East Eurasia. Over time they started to differ genetically, including the divergence between Papuans and Aboriginal Australians starting around 37,000 years ago.
This is inconsistent with the interpretation of the Two-Layer and Regional Continuity models proposed by anthropological and linguistic studies. Both of these hypotheses assume that Australo-Melanesian ancestors were the only inhabitants of the Archipelago. However, this latest hypothesis told us that since 50,000 years ago, our archipelago (which was at that time the Sundaland region) has been inhabited by a diverse group of humans, both physically and genetically.
Currently, the genetic component of basal East Eurasian population is mostly found in Eastern Indonesia, although some of these components are still owned by people born in Western Indonesia such as the Batak, Dayak Lebbo' tribes in East Kalimantan, Java and Bali. This argues for no 'replacement' occurred when Austronesian-speaking migrants came to the Archipelago. Instead, what happened was admixture.
When the Last Glacial Maximum occurred 30,000 to 11,000 years ago, sea levels receded to 120 meters, uniting Sumatra, Java and Borneo. In this time period, not much can be revealed from a genetic perspective other than that each population followed its own evolutionary trajectory.
The hypothesis of a two-way movement between the mainland and islands of Southeast Asia has then, become highly likely. This could explain why we share a common genetic component with people in mainland Asia such as Vietnam, Thailand, and Cambodia (Austroasiatic-speaking groups). It was also during this period that the Australo-Melanesians encountered another Denisovan group about 30,000-15,000 years ago, to the east of the Wallace's Line, causing them to the only ones inheriting the genome.
Entering the Holocene period (11,000-3,200 years ago) there was a divergence, or branching of two populations, in East Asia. Appearing to become the Ancient Northern East Asia (ANEA) and Ancient Southern East Asia (ASEA), the boundary of the two groups is the Yangtze River. They are known by anthropologists as the Mongoloids. These two populations started to differ genetically about 10,000 years ago. This analysis was only published in 2020 by many ancient DNA studies in East Asia, Tibet and Southeast Asia including from the Pacific.
In this period as well, sea level rose quite dramatically, known as the '4.2k event', and severely impacted those living on the coast, such as the east coast of Asia. Populations with the ASEA component begin to migrate in all directions in search of a new place to live. Taiwan is one of their destinations. In the next 500 years they have reached the Mariana Islands, Borneo, Sulawesi, New Britain, and finally reached Vanuatu and Tonga about 3,000 years ago. This event was known as the Austronesian expansion.
Entering the historical period, spices have brought traders from India, Persia, Arabia and Europe to the Southeast Asian islands. Displacement and assimilation continued. At the end of the 19th century, many Javanese, Chinese and Indians moved to East Sumatra as coolies. And Europeans arrived as tobacco entrepreneurs. The practice of Tuan and Nyai is also very fertile. The result is the white people, with genetics similar to Europeans, speaking Javanese in Sumatra.
All the research we have explored earlier shows that genetic, cultural, and linguistic diversity is the product of a complex history that occurred in the past. 'Admixture increases diversity': meaning genetic mixing of different groups increases diversity. This is a paradigm that must be held when uncovering Indonesia's human history.
And now, is time to end our time travel, get back to the present, and appreciate our differences!
