Homo luzonensis

*Homo luzonensis*, sometimes called the ubag (after a mythical caveman), is an extinct species of hominin that lived in the Philippines during the Late Pleistocene.

## History

The first *H. luzonensis* were found in 2007, exclusive to Callao Cave in Northern Luzon. In 2010, the French Florent Détroit and Filipino Armand Mijares et al. assigned the remains to what would have been apomorphic *Homo*. However, in 2019, researchers studying 12 additional remains pin-pointed a mix of apomorphic and primitive *Australopithecus*-like features, and assigned the 12, including the remains Détroit and Mijares et al. studied in 2010 to a new species, *H. luzonensis*, named from the island of Luzon where the type locality is. CCH6 represents the upper right molars and premolars, paratypes being CCH1 (the right third metatarsal of a foot), CCH2 AND CCH5 (two finger phalanges) CCH4 (a left premolar) and CCH9 (right third molar). CCH7 is a femoral shaft of a juvenile, with all remains being at least 3 individuals, all housed in the National Museum of the Philippines in Manila. Like other tropical hominins, DNA extraction failed and the exact placement this species sat is unknown. Like *H. floresiensis*, *H. luzonensis* was likely ancestral to *H. erectus* dispersal across Southeastern Asia. However, it is still likely they descended from an as-of-yet unknown species, possibly earlier than *H. erectus*. The remains themselves date to 50,000 years, but evidence of hominin activity range as far back as 771,000-631,000 years ago.

A skull and mandible of uncertain completeness known from Manilla and described by D. Sánchez y Sánchez (1929) was found 2.5-3 meters or 2.1-2.7 meters below the surface of the Pásig River alluvia during construction of the "Manila Athenaeum" (Athenaeum Condominium?). Apparently, it is small, subbrachycephalic (with a cranial index of 80-83, making the neurocranium ovular, broad and short), having high prognathism, no chin, being platyrhyne, lacking the nasal spine and having "smooth and delicate shapes". The mandible is noted as being similar to the simian jaw of Piltdown, having an oblique profile, ascending ramus, a body that is short, narrow and low and condyles that are small but somewhat wide. Sánchez y Sánchez considered it "frankly pithecoid", belonging to a "pre-Neanderthaloid" race that was considered ancestral to modern indigenous of Luzon. It is likely from the Late Pleistocene but has remained undated since nothing was associated with it. He named it *Homo manillensis*, but this name has been lost in literature. Because so many details match and it was considered a new species, the skull may be a *Homo luzonensis*.

## Description

Due to insular dwarfism, *H. luzonensis* may have shrunk in size to become pygmy, with more remains needed to verify size. *H. luzonensis* has a variety of traits more similar to *Australopithecus* and early *Homo* than anatomically apomorphic *Homo*. *H. luzonensis* teeth are characteristically small and mesiodistally shortened, with molars smaller than *H. floresiensis*. Like more recent and anatomically apomorphic *Homo*, molars decrease in size near the back of the mouth and the enamel-dentin juncture lacks characteristic defined weaving crenulations, with the juncture itself being most reminiscent of Asian *H. erectus*. Compared to the molars, the premolars are strangely large. This is most similar to *Paranthropus* than any *Homo*, although the postcanines greatly differ from the latter in size and shape. The premolars resemble *Australopithecus*, *Paranthropus* and plesiomorphic *Homo*. The bones in the fingers are long, slender and curved. This feature is seen in *Australopithecus*, *H. floresiensis* and certain apomorphic *Homo*. Their hands are dorso-palmarly compressed with a well-developed flexor sheath attachment, observed in *Australopithecus* and early *H. habilis*. The break near the knuckle is strongly developed and angles nearer to the wrist than the figure, unique to this species. Foot bones are morphologically unique in *Homo*, but indistinguishable from *A. africanus* and *A. afarensis*. Typically, *Australopithecus* limbs are interpreted as early bipedal adaptations and potential suspensory behaviour adaptations in trees. However, *H. luzonensis* is so fragmentary it limits extrapolation in locomotion methods. Due to fragmentary material, it is difficult to determine the average height of *H. luzonensis*, but they are thought to have been a similar height to some ethnic groups in the Philippines. As a rough estimate, males were 151 centimeters (4 feet, 11 inches) tall and females 142 centimeters (4 feet, 8 inches) tall. It is debated whether *H. luzonensis* was a pygmy species.

## Classification

Lee Berger believes *H. luzonensis* is a product of "an almost endless variant of isolation", believing molecular biology will back this in the future. This species is left out of many phylogenetic studies and diagrams because it's classification and affinities are largely unknown. A 2022 paper finds that *H. luzonensis* and *H. floresiensis* evolved from *Homo erectus* groups that had dispersed and became isolate during speciation events that occurred at least twice during the insular environments of the Pleistocene.

## Paleobiology

Since Luzon was an island during the Quaternary, the species or their ancestor populations must have made a substantial oceanic crossing, past the Huxley Line.

### Technology

Nearly 90% bone fragments from Callao Cave were from Philippine deer, meaning these hominins brought their carcasses into caves regularly. Except for a tiger population on Palawan, there is no evidence of large carnivores existing in the Philippines during the Pleistocene, which Is why evidence of active hominin activity is present. The Philippine warty pig was prevalent at this place and time. Deer tibia have cut marks, with a lack of material of use in the caves either resulting in the use of organic material rather than stone or food processing away from caves. The earlier Cagayan Valley preserves an almost complete *Rhinoceros philippinensis* 771,000-631,000 years old bearing butchering evidence. The site is also littered with 6 lithic cores, 49 lithic flakes and 2 hammerstones, all similar to the chert industry of the Early Paleolithic Arubo 1 in Luzon. The remains of a *Stegodon*, the Philippine deer, freshwater turtles and monitor lizards were also present.

## References

* https://en.wikipedia.org/wiki/Homo\_luzonensis
* https://twitter.com/LeeRberger/status/1432054186984751107
* https://www.sciencedirect.com/science/article/abs/pii/S0047248421001767
* https://books.google.ca/books?id=Sl3WAAAAMAAJ&
* https://www.britannica.com/science/cephalic-index
* https://books.google.ca/books?id=jj1iftPqCssC&pg=PA86&lpg=PA86&dq=homo+manillensis&source=bl&ots=fhs7ax15iS&sig=ACfU3U3pGczyQwvPgkcOZN0JHe1wjwZZlQ&hl=en&sa=X&ved=2ahUKEwjQicS8obf4AhVMLs0KHcCEDrIQ6AF6BAgZEAM#v=onepage&q=homo%20manillensis&f=false
* https://archive.org/stream/in.ernet.dli.2015.56131/2015.56131.Man-In-India-Vol10\_djvu.txt
* https://www.cervantesvirtual.com/obra/estado-actual-de-las-investigaciones-sobre-el-hombre-fosil/
* https://archive.org/stream/fossilmaninspain00ober/fossilmaninspain00ober\_djvu.txt