Prehistoric gibbons and monkeys from Niah, and the Dutch palaeontologist Dirk Albert Hooijer

Heritage Snippets of Sarawak by FoSM

Heritage Snippets of Sarawak

By Lim Tze Tshen

MODERN PRIMATES IN BORNEO AND AROUND NIAH NATIONAL PARK

PERHAPS due to their human-like nature and complex social behaviour, gibbons and monkeys have always occupied a special place in the hearts of naturalists and nature lovers. How many a time have the melancholy songs of the gibbons, frequently heard in the early morning, consoled the souls of those who seek refuse in the misty forests of Borneo? Has not the playful nature of a young langur reminded us of our mischievous youth? More importantly, their presence in the forests is a sign of a healthy ecosystem since they, like many bird species, are major seed dispersal agents for a great majority of plants in Borneo.

The tropical rainforest in Borneo is home to a spectacular number of primate species. The most recent records show that it boasts no fewer than 20 different kinds of non-human primates (for comparison, Peninsular Malaysia has only 14 species).

Table 1: Non-human primates recorded from Borneo, Sarawak, and Niah (modern-day and prehistoric). Species in bold refer to Bornean endemics. © L.T.Tshen.

Out of the total found in Borneo, 14 species are endemic to the island, which means they occur nowhere else in the world, except only in Borneo. Remarkably, all the langurs from the Presbytis group and all the gibbon species that now live on the island are Bornean endemics—native species that evolved and diversified locally in Borneo. Other Bornean endemics include the Kayan and Bornean slow lorises, the proboscis monkey, and the Bornean orangutan.

All the 14 species found in Sarawak (Table 1) are either shared with other regions in southeast Asia or nearby areas within Borneo. None seems to have their distribution range confined specifically within Sarawak.

Figure 1: Forest scene outside the West Mouth of Niah Cave. © L.T.Tshen.

Public information about recent primate fauna found in and around the forests of Niah National Park is not readily available or scattered among various sources:

  • A short-term wildlife survey conducted in 2004 by Faisal Ali Anwarali Khan and his team had recorded the presence in Niah forests of only two species of primates: the long-tailed and pig-tailed macaques.
  • Other sources of information from the 1990s onwards suggested that the silvered langur, Hose’s grey langur, red langur, Sarawak langur, and, occasionally, the proboscis monkey can be found near here.
  • A pamphlet ‘Primates of Malaysia: Pocket Identification Guide’ published in the early half of 2023 indicated the presence of only one gibbon species in Niah National Park—the Abbott’s gibbon. Yet, it also showed that Niah is very close to the distribution range of another species, the north Borneo gibbon.
  • Orangutans from the area were last noted in the late 19th century (Prehistoric and Some Long-gone Orang-utans of Sarawak; Malaysian Naturalist—Sarawak’s Biodiversity at a Glance, 2022).

We do not know if there is any confirmed sighting here of the smaller primates, such as the tarsier and slow loris.

In his 1958 Sarawak Museum Journal article, Food Bone in Niah Cave Excavations, (-1958) A Preliminary Report, Lord Medway, a prominent biologist on Bornean mammals, provided us with some interesting field observations of living animals near Niah forests back in the 1950s. In a footnote, he recorded that the long-tailed macaque is ‘abundant around the caves and enters freely when man is absent’, while the pig-tailed macaque is ‘also found locally but has never been seen near the caves’. Of the langurs, he noted that the red langur is ‘common in the jungle immediately surrounding the caves, and will come to the mouths’ of the caves, but the silvered langur has only been met ‘in the forest further afield’.

A 45,000-YEAR-OLD HISTORY OF GIBBONS AND MONKEYS

Our knowledge about the history of gibbons and monkeys living around Niah, however, is not limited only to the recent past. Together with other animals hunted by prehistoric humans, their skeletal remains were preserved in the archaeological sediments deposited inside Niah Cave. Some were recovered from deep excavated levels, perhaps contemporaneous with the oldest known human remains from the site. Skillful systematic studies conducted in the past revealed that not all species of monkeys and gibbons were evenly distributed across the excavated layers—for instance, remains of some species were found to be more abundant than those of others, while some species seem to have appeared later in time than the others. These relative differences are thought to be reflective of changing hunting preferences, and perhaps in part due to preservational biases of the archaeological site.

Remains of gibbon are rare, with less than 20 recognisable specimens, according to a report published in 1996 by the American palaeontologist, Terry Harrison. Equally rare among the primate remains are the pig-tailed macaque and the slow loris. In fact, slow loris remains were only reported in the 1958 paper mentioned above, and no subsequent finding is known since then.

Figure 2: Prehistoric gibbon lower jaw with one attached tooth, recovered from one of the Niah archaeological sites, collected on 18 February 1958. © L.T.Tshen.
Figure 3: Prehistoric lower jaw of a baby pig-tailed macaque, recovered from the Gan Kira site in Niah Cave. Original field label (left) and the identification note written by Hooijer (top of specimen). © L.T.Tshen.

Remains of the long-tailed macaque, however, were commonly found, with more than 200 specimens known. Among the langurs, the Presbytis species were not only better represented by a larger amount of remains than those of the Trachypithecus, but they were also found to be present throughout the excavated layers, according to the original investigation published in the 1962 issue of Sarawak Museum Journal. The Trachypithecus is a larger langur than the Presbytis, and their remains were found only in layers above a certain depth. In other words, it would have seemed that Trachypithecus ‘appeared’ on the scene only at a much later time period than most of the Presbytis langurs.

Figure 4: Prehistoric lower jaw of an adult female langur, recovered from the Gan Kira site in Niah Cave. Original field label (left) and the identification note written by Hooijer (top of specimen). © L.T.Tshen.
Figure 5: Prehistoric lower jaw of an adult female silvered langur from Niah Cave and the photographic image that Hooijer published in the 1962 issue of Sarawak Museum Journal. © L.T.Tshen.

Though not present in modern-day Niah, remains of orangutan were found to be very common across the archaeological layers. The apparent absence of any skeletal remains of the proboscis monkey in Niah presents another prehistoric puzzle yet to be solved—the species may either be totally absent in the past, or their remains are present, but not readily recognisable.

DIRK ALBERT HOOIJER AND HIS STUDIES OF PREHISTORIC NIAH FAUNA

The very foundation of our understanding of Niah prehistoric fauna was laid down by way of the solid and meticulous studies conducted by many previous workers mentioned above. One of them is the Dutch vertebrate palaeontologist, Dirk Albert Hooijer (1919–1993).

Figure 6: Dr Dirk Albert Hooijer at work in his study in the Netherlands. Courtesy of Annemarie Hooijer.

Hooijer was born in Medan (Sumatra) and spent his youthful years in Bogor (Java), but moved back to the Netherlands in 1932 together with his family. In 1941, he joined the staff of the Rijksmuseum van Natuurlijke Historie in Leiden (now known as the Naturalis Biodiversity Center), and later became a full curator there in charge of the large collection of vertebrate fossils collected from various localities in the Dutch East Indies (present-day Indonesia).

His superb skills and originality in studying the morphological evolution of fossil and modern-day animals gained him a high reputation among colleagues, one of whom described him as a scientist of ‘intense commitment’ and an ‘enthusiastic expert who aimed at perfection’.

During the course of his highly productive academic career, he studied fossil mammals and reptiles from many places around the world, including Indonesia, Malaysia, China, India, the Middle East, Africa, the Netherlands, the Antilles, and South America. He produced more than 270 scientific articles, and was easily among the most prolific of palaeontologists who worked on southeast Asian mammal fossils since the 1940s. Many of his published works have become cornerstones to our understanding of past animal life that flourished in Asia since 2.5 million years ago.

Furthermore, he was among the first scientists who applied rigorous statistical methods in the study of southeast Asian mammal fossils, thereby, providing us with a new way of looking into the nuances of how prehistoric fauna may have changed over time and across different places. In their scientific investigation, modern-day palaeontologists still make frequent references not only to the fossils that he had studied, but also his publications, many of which are now made downloadable in electronic version and free of charge through the Internet.

His doctoral and subsequent research dealing with Asian fossil rhinoceroses in the 1940s–50s may have attracted the attention of Tom Harrisson (1911–1976), the curator of Sarawak Museum who started the archaeological investigation in Niah Cave. Archival records in the museum indicated that the two men started corresponding with each other since the 1950s on matters related to Asian rhinoceroses (see here, https://dayakdaily.com/historical-glimpses-of-sarawaks-hairy-rhinoceroses-part-two/).

In the end, he was entrusted to conduct detailed studies on some of the animal remains recovered from Niah, especially the primates. The museum still keeps many of his correspondence records with Tom and Barbara Harrisson (1922–2015) up till the retirement of the Harrissons from Sarawak—a wealth of historical documents about Niah research yet to be fully studied by modern historians.

Among his many technical publications on prehistoric mammal faunas of Asia, those that are directly relevant to Niah include four articles that appeared in the Sarawak Museum Journal:

1960 — (1). The Giant Extinct Pangolin (Manis palaeojavanica Dubois) from Niah.
(2). The Orang-Utan in Niah Cave Pre-history.
1962 — Prehistoric Bone: The Gibbons and Monkeys of Niah Great Cave.
1963 — Further “Hell” Mammals from Niah.

Two more Niah-related articles published elsewhere include:

1961 — An Extinct Giant Pangolin and Associated Mammals from Niah Cave, Sarawak; Nature (co-authored with Tom Harrisson and Lord Medway).
1976 — Some Paleontological Results from Excavations at Niah Caves, Sarawak; Borneo Research Bulletin.

The scientific names of certain Bornean primate species may have changed since the 1960s when Hooijer first published the results of his Niah research. Besides that, our understanding of the diversity of Bornean primates has also improved tremendously with recent advances in the field of primatological research in southeast Asia.

Therefore, it is not surprising that some of Hooijer’s original interpretation of the Niah data may be challenged by present-day scholars whom, in many cases, have access to more research materials than what were available to him. Nevertheless, his morphological documentation and identification of the bone materials are found to be scientifically accurate and valid—a testament to his outstanding scholarly ability and strong power of observation. Two of the many qualities, gained through years of training and diligent studies of a wide range of specimens, that made him a top-notch palaeontologist.

Fortunately for us, all the Niah materials that he had studied and published, including the gibbons and monkeys, together with his original identification notes, are all accounted for, as revealed through recent inventory of Niah animal remains conducted a few years ago (see Figures 2 to 5).

The inventory showed more than this—there are primate materials from past excavations at Niah Cave that have not been fully studied, awaiting future scientists to unlock their secrets. Truly, a treasure trove of Sarawak prehistoric heritage yet largely unknown.

Figure 7: Part of the collection of prehistoric monkey remains recovered from the 1950s excavation in Niah Cave. Important research material waiting for future scientists to study in full. © L.T.Tshen.

ACKNOWLEDGEMENTS

My gratitude to the family members of Dr Dirk Albert Hooijer, especially Annemarie, for sharing the many scientific publications of her father, and for the kind permission to reproduce here an image of him. Senior colleagues (Earl of Cranbrook, Susan Turner, and Gerrell Drawhorn) who know Hooijer personally, for sharing their stories about Hooijer. Studies of the many zooarchaeological remains from Niah excavations were made possible through the Niah Cave Project of University of Cambridge and the Sarawak Museum Campus Project.

LIM Tze Tshen, honorary secretary of Friends of Sarawak Museum, is a vertebrate palaeontologist and zooarchaeologist. He is reachable through limtzetshenyahoocom.

“Heritage Snippets of Sarawak” is a fortnightly column.

— DayakDaily