Interior of Callao Cave
in the Philippines, where the fossil remains were found.
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[note 1]) and a sea crossing has always been necessary to reach Luzon and other oceanic islands of the Philippines.
Five of seven fossilized teeth ascribed to H. luzonensis.
The small sizes of the hominins' molars suggest that it may have undergone island dwarfing, similar to H. floresiensis, although no estimate of its height is currently possible. An expert not associated with the study commented that the curvature of its digits suggests it may have climbed trees.
The fossil human remains were associated with the remains of deer (Cervus mariannus), wild pig, and an extinct bovine. Some of the animal bones exhibit potential cut marks, suggesting that they were butchered. Much earlier stone tools and the almost complete fossilized skeleton of a butchered rhinoceros dating back to c. 700,000 years ago were found by Thomas Ingicco and colleagues in the nearby San Pedro site in Rizal, Kalinga.