In 2007, during an excavation on the island of Luzon in the Philippines, archeologist Armand Salvador Mijares discovered a 67,000-year-old foot bone that led scientists to rethink the history of human evolution.  The bone had features resembling hominins—a subfamily of primates comprised of modern Homo sapiens and others closely related human species.  The finding provided the earliest direct evidence of human presence in the Philippines, but at the time it was unclear to which specific species the bone belonged.  Now, Mijares and his group have unearthed additional bones from the same site that identify these early inhabitants of Luzon as an entirely new species of ancient humans.

The newly discovered bones—two hand bones, two foot bones, a femur, and seven teeth—originate from at least three separate individuals and date back to between 50,000 and 67,000 years ago.  After excavating the bones, Mijares analyzed their shape and physical characteristics using CT scanning (a type of x-ray scan) and 3D measurement techniques.  While they shared features of both Homo sapiens and more primitive species, the combination of characteristics across the set of bones was unique, necessitating their assignment to a new human species.  Mijares named the species Homo luzonensis after the island where the bones were discovered.

Although the discovery of a novel ancient human species is hugely impactful to the field of evolution, the conclusions from the study have been met with some controversy.  Critics doubt whether the differences between the recently discovered bones and those of established species are convincing enough to warrant a new species designation.  For example, it is possible that reproductive isolation of the Luzon islanders from the mainland population over time could have resulted in unique bone characteristics arising from genetic drift, or evolution by chance alone, and that the differences are not enough to warrant the assignment of a new species.  The discovery of new Homo luzonensis samples may shed additional light on this question.

Managing Correspondent: Benjamin Andreone

News Article: An Ancient Human Species Is Discovered in a Philippine Cave. The New York Times 

Original Article: A new species of Homo from the Late Pleistocene of the Philippines. Nature 

Image Credit: Callao Cave Archaeology Project