88. CALLAO MAN aka HOMO LUZONENSIS

CALLAO MAN aka HOMO LUZONENSIS

Dr. Troy Alexander G. Miano

10 April 2019

Long before I became the Provincial Tourism Officer of Isabela, it has been in my system to tour balikbayans in Isabela and nearby Cagayan province particularly in Peñablanca town. I am very amazed in one of the limestone caves located in this municipality particularly the Callao Caves in Barangays Magdalo and Quibal. This seven-chamber show cave is one of 300 caves that dot the area and the best known natural tourist attraction of the province of Cagayan which is located about 24 kms northeast of Tuguegarao City and within the Peñablanca Protected Landscape and Seascape. The name “Peñablanca” is a Spanish term which means “white rocks” referring to the presence of white limestone rocks in the area.

When I was in Ateneo Grade School, we were taught in Araling Panlipunan about the Tabon Man discovered in the Tabon Caves in Lipuun Point in Quezon, Palawan. The remains were discovered by Dr. Robert B. Fox, an American anthropologist of the National Museum of the Philippines, on May 28, 1962. Dr. Fox was the father of my immediate superior in the Philippine Senate, our chief-of-staff, Atty. Glenn Robert Fox of the Office of Senator Heherson T. Alvarez. The Tabon remains, fossilized fragments of a skull and jawbone of three individuals, were believed to be the earliest human remains known in the Philippines which date back to 16,500 years ago until a newly-described species of human living between 50,000 to 67,000 years ago, Homo luzonensis, discovered in Callao Cave was confirmed this year.

For the past decade, I kept on browsing the net for updates on the Callao Man. The net revealed news and data of the Callao Man now known scientifically as Homo luzonensis. Callao Man refers to fossilized remains discovered inside Callao Cave in 2007 by Armand Salvador Mijares of the University of the Philippines Diliman. Specifically, the find consisted of a single 61 mm (2.4 inches) metatarsal which, when dated using uranium series ablation, was found to be at least 67,000 years old. If definitively proven to be remains of Homo sapiens, it would antedate the 47,000-year-old remains of Tabon Man to become the earliest human remains known in the Philippines, and one of the oldest human remains in the Asia Pacific. It has been noted by researchers that Callao Man was probably less than four feet tall. Researchers also believe that Aetas, mountain dwellers today on Luzon Island, could be descendants of the Callao Man. In 2010, more human remains were discovered in the cave and were tentatively known by the scientific community as remains of Homo sapiens. More bones discovered in 2015 by Mijares led to scientific investigation on the real genetics of the human remains.

After a long wait, great news greeted me in the net. This day, an article by paleoanthropologist Florent Détroit et al. in the scientific academic journal Nature described the subsequent discovery of "twelve additional hominin elements that represent at least three individuals that were found in the same stratigraphic layer of Callao Cave as the previously discovered metatarsal" and identified the fossils as belonging to a newly discovered species, Homo luzonensis, on the basis of differences from previously identified species in the genus Homo. This included Homo floresiensis floresiensis and Homo Sapiens. However, some scientists think additional evidence is required to confirm the fossils as a new species, rather than a locally adapted population of other Homo populations, such as Homo erectus. The project team led by Dr. Mijares includes Dr. Florent Detroit of the National Museum of Natural History in Paris, France and researchers from the University of Bordeaux, Paul Sabatier University and the University of Poitiers in France as well as Griffith University in Australia.

Nationalgeographic.com further reveals that although the initial hypothesis of human migration to the Philippines proposed the use of land bridges during the last ice age, modern bathymetric readings of the Mindoro Strait and Sibutu Passage suggest that neither would have been fully closed (which correlates with the Philippines being biogeographically separated from Sundaland by the Wallace Line) and a sea crossing has always been necessary to reach Luzon and other oceanic islands of the Philippines. The small sizes of the hominins' molars suggest that it may have undergone island dwarfing, similar to Homo floresiensis, although no estimate of its height is currently possible. The curvature of its digits suggest it climbed trees.

The 2019 Nature article describing Homo luzonensis noted that: "The presence of another and previously unknown hominin species east of the Wallace Line during the Late Pleistocene epoch underscores the importance of island Southeast Asia in the evolution of the genus Homo." Quoting Mijares, a National Geographic grantee, “For a long, long time, the Philippine islands [have] been more or less left [out]," but the Homo luzonensis flips the script, and it continues to challenge the outdated idea that the human line neatly progressed from less advanced to more advanced species. I felt very proud of this find since I am not only from Luzon Island but particularly from Cagayan Valley and the remains are only 137.4 kms away from my home in Cabatuan town. I am also very fortunate that it was during my lifetime when a new branch of humankind was discovered.