UP-led international team discovers new human species in the Philippines

| Written by Andre DP Encarnacion

Video from the UP Media and Public Relations Office


An international multidisciplinary team, led by University of the Philippines Associate Professor Armand Salvador B. Mijares, discovered a new human species, the Homo luzonensis, from an excavation site inside Callao Cave in Peñablanca, Cagayan.

Mijares said the hominin fossils and teeth are from at least three individuals, nicknamed Ubag after a mythical cave man, that were excavated in 2007, 2011 and 2015. He and the members of his team, paleoanthropologist Florent Détroit of the Muséum national d’Histoire naturelle, zooarchaeologist Philip Piper of Australian National University, and geochronologist Rainer Grün of Griffith University, dug up the hominin fossils from a sedimentary level located three meters below the current surface of the cave floor.


Figure 1. The different fossils remains of Homo luzonensis from Late Pleistocene sediments at Callao Cave. a, holotype CCH6: postcanine maxillary teeth in occlusal (left) and buccal (right) aspects, b, left P3 or P4 CCH8: occlusal (left) and buccal (right) aspects, c, right M3 CCH9: occlusal (top) and buccal (bottom) aspects d, juvenile femoral shaft CCH7 (anterior, lateral, posterior aspects. e, distal manual phalanx CCH5 (dorsal, lateral/medial, palmar aspects) f, intermediate manual phalanx CCH2 (dorsal, lateral, palmar aspects).g, 3rd metatarsal discovered in 2007 h, intermediate pedal phalanx CCH3 (dorsal, medial, plantar aspect)..) i, proximal pedal phalanx CCH4 (dorsal, lateral). Source: A new species of Homo from the Late Pleistocene of the Philippines, Nature, 2019


Uranium-series (u-series) dating, which is a method used to calculate age via the radioactive decay of uranium, determined the fossils to be 50-67,000 years old. These would make them the earliest human remains to be discovered in the Philippines, predating even the Homo sapiens found on Palawan island to the south estimated at 30-40,000 years.

The species was first described by Mijares and his team in a 2010 article through a single metatarsal bone. Comparative analyses via 3-dimensional imaging methods and geometric morphometrics showed that Homo luzonensis had a mix of primitive features resembling Australopithecus and more modern ones closer to Homo sapiens. This singular combination of traits distinguishes it from other representatives of the genus Homo, especially its contemporaries known in Southeast Asia like Homo floresiensis, which was discovered in Indonesia in 2004.


Prof. Armand Salvador Mijares explains the unique anatomy of Homo luzonensis at a press conference at the UP College of Science Auditorium. Photo by Misael Bacani, UP MPRO.


Luzon, which is the largest island in the Philippines, was not known to be accessible by foot during the Quaternary period (around 2.588 million years ago to present) and is known for its high rate of endemism. Discovered anthropogenic elements such as stone tools and the remains of animals, including nearly a complete rhinoceros with clear marks of butchery in the Kalinga, are evidence that hominines were present on the island for at least 700,000 years ago.


Figure 2. (Left photo) Location of Callao Cave in north of Luzon Island, Philippines, which has never been accessible by foot from the Asian continent during the Quaternary epoch (medium gray and light gray tones indicate the extension of the emerged lands at lower sea levels of 50 and 120 m respectively). (Right photo) View of the excavations of Callao Cave in 2011. Source: A new species of Homo from the Late Pleistocene of the Philippines, Nature, 2019


Like Homo floresiensis, which was nicknamed “hobbit” by the scientific community, Homo luzonensis probably represents another species of the genus Homo that evolved under the effects of insular endemism, while being unique. Where it came from and how it got here remain largely a mystery, but its presence highlights the complexity and diversity of hominine migrations and the evolutionary history in the islands of Southeast Asia.

“The study situates the Philippines as a major area for evolutionary research,” Mijares said. “This discovery, to me, is a dedication to the Filipino people. It is our contribution to Filipino heritage and to the world’s heritage.”


Professor Armand B. Mijares with the history-making fossils of Homo luzonensis. Photo by Misael Bacani, UP MPRO.


The project that led to the discovery of Homo luzonensis was funded by the Wenner-Gren Foundation, the Leakey Foundation Research Grant, and the University of the Philippines via the Enhanced Creative Work and Research Grant in cooperation with the National Museum of the Philippines, the Cagayan Provincial Government, and the Protected Area Management Board-Peñablanca.