A trove of stone tools and fossilized butchered animal bones unearthed in the Philippines has forced archaeologists (again) to rewrite our understanding of ancient human expansion into the cluster of Southeast Asian islands between Borneo and New Guinea.
Discovered by an international research team in a cave on Luzon, the northernmost island of the Philippines, advanced dating performed on the objects places hominin species in Wallacea – the area between the Asian and Australian continental plates – about 700,000 years ago. According to their paper, published in Nature, this is about half a million years earlier than previously believed.
The complete findings included 57 stone tools, a near-complete skeleton from an extinct rhinoceros species that showed signs of cutting to extract bone marrow, and remains from stegadons, Philippine brown deer, freshwater turtles and monitor lizards, all buried in a layer of clay-rich soil.
“This evidence pushes back the proven period of colonization of the Philippines by hundreds of thousands of years,” the authors write, “and furthermore suggests that early overseas dispersal in Island South East Asia by premodern hominins took place several times during the Early and Middle Pleistocene stages.”
Due to the constant re-shifting that occurs with each new find, human evolution researchers rarely make sweeping proclamations. Yet until quite recently, many posited that hominin species would have had extreme difficulty spreading to the Wallacean islands from the Asian mainland to the east due to the deep-water straights underlying the continental shelf. After all, there are no indicators that these groups had the capability to build boats, let alone simple rafts.
Now, the evidence is piling up that primitive human species were somehow able to reach these islands in several separate settling events rather than one fortuitous wave of migration.
Prior to this study, the oldest indicators of a hominin presence on the Wallacea were stone tools unearthed on the island of Flores in 2010, dated to 1 million years ago. A handful of actual fossils found in 2003 showed that a small-brained, 3.5-foot-tall (1.06 meters) species of early human species called Homo floresiensis, nicknamed ‘the Hobbit’, inhabited the island between 190,000 and 50,000 years ago.
Hominin establishment on Luzon, specifically, had been traced back to 67,000 years ago, following the discovery of a toe bone from a petite-bodied hominin – possibly H. floresiensis – in 2010. Dr Gerrit "Gert" van den Bergh speculates that a yet-to-be-discovered ancestral group created the Luzon tools described in this study and those found on Flores.
"Our hypothesis is that the 'Hobbit' ancestors came from the north, rather than traveling eastward through Java and Bali," he said in a statement.
He further explains that tsunamis, a common occurrence in the tectonically active region, could have swept large numbers of humans and animals living in coastal regions to the north, distributing them on islands to the south.
"If animals did reach these islands by chance, by entering the sea and following the currents south, then you would expect the further south you go the fewer species you would find – and that's what we see."
Homo sapiens, the modern human species, is believed to have evolved and migrated out of Africa approximately 200,000 years ago, reaching the Philippines about 50,000 years ago.