In 2007, inspired by the discovery of the Homo floresiensis at Liang Bua Cave in Flores Island, Indonesia, an archaeological team led by Mijares from the University of the Philippines continued excavations in Callao Cave in the hopes of finding evidence of early hominin activity [4]. During this excavation season, a hominin fossil was discovered among the fossilized bones from Layer 14 [2].  

CCH1 (II-77-J3-7691) is a hominin right third metatarsal (MT3) found in Callao Cave. It was broken in two parts around the mid-shaft, but with the exception of the broken distal head the bone is almost complete and well-preserved. The morphological features and the fossil's size and shape characteristics indicate that it belongs to the genus Homo. Its preliminary description also suggests a smaller general size which is only observed in the region in the Homo floresiensis and in small-bodied Homo sapiens, such as the present-day Philippine Negritos [2].

CCH1 was directly dated using U-series ablation to a minimum age of 66.7±1 ka making it the oldest known human fossil in the Philippines. This indicates that a hominin species crossed water between Sundaland and Wallacea to reach Luzon island as early as 67,000 years ago [2][3]. 

In a 2019 Nature publication [3], it was announced that CCH1 and twelve additional hominin fossils from subsequent excavations on Callao Cave belong to a new species Homo luzonensis, named after the Philippine island of Luzon. The morphology of the Homo luzonensis reveals an unexpected mix of both ancient and more modern traits that is different from other species of Homo which led to it being assigned to a new taxon. The CCH1 foot bone that served as the new species' paratype resembles those of the australopithecines [2][3][5].