Researchers have recovered Homo erectus bones from the seafloor, which points to an unknown hominin population hunting on land that is now underwater in Southeast Asia.

Far before modern humans ever walked the Earth, our Homo erectus ancestors made arduous journeys to the present-day islands of Southeast Asia. Fossil remnants of H. erectus have been left all across this region, and now, two newly discovered skull fragments belonging to the species have added a new angle to their story. A study published in the journal Quaternary Environments and Humans reveals that the fossil remains were found after a marine sand extraction project in the Madura Strait, a stretch of water between the Indonesian islands of Java and Madura. By examining the fossils, archaeologists have opened a window into the lives of H. erectus who took advantage of low sea levels to spread across a now-submerged landmass 140,000 years ago. H. erectus Fossils on JavaAfter leaving Africa nearly 2 million years ago, H. erectus trekked all the way through Asia and eventually hit the Southeast Asian islands closer to 1.5 million years ago. Fast-forward to the late 19th century, and the first set of H. erectus fossils was found by Dutch scientist Eugène Dubois on Java, enshrined in archaeological history as the Java Man. But with Java surrounded by water in modern times, one may wonder, how did H. erectus land there in the first place? In the ancient past, this part of the world was much different than it is today. Millions of years ago, a landmass called Sundaland connected islands like Bali, Borneo, Java, and Sumatra. Sundaland was exposed during glacial periods when sea levels were low, forming a land bridge that paved the way for human migration flows at various points in history. This is how H. erectus and other species could reach Java. Rare Vertebrate FossilsThe new fossils shed light on Javanese H. erectus much later in their existence, around 140,000 years ago. Researchers involved with the study say that vertebrate fossils have never been found in the area that was once Sundaland, now submerged in the ocean. “This makes our discoveries truly unique,” said Harold Berghuis, an archaeologist at Leiden University, the Netherlands, in a statement. “The fossils come from a drowned river valley, which filled up over time with river sand. We have been able to date the material to approximately 140,000 years ago. That was the penultimate glacial period. Large parts of the northern hemisphere were covered by glaciers, and so much water on Earth was stored in ice caps that the global sea level was 100 metres lower than today.”The fossils show that H. erectus living on Java at the time dispersed throughout the lowlands of Sundaland when the sea level had receded enough. They would have traveled along river systems such as the Brantas and Solo Rivers, finding edible plants and shellfish. Read More: Who Was Homo Soloensis, the “Solo Man?”The Extinction of H. erectusThe researchers say that Javanese H. erectus hunted bovids (the family that includes cattle and buffalo), and potentially learned hunting practices through contact with more modern human species living on the Asian mainland. The final survivors of the entire H. erectus population were living in Java at the time of their death. Homo erectus soloensis (or the Solo Man), a subspecies of H. erectus, is believed to have lived along the Solo River from around 117,000 years to 108,000 years ago, marking the last known record of H. erectus. The extinction of the species may have occurred as a result of a changing climate that caused Java to morph from an open woodland environment into a rainforest.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Britannica. Java manJack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.

36 fossil fragments from vertebrate animals were documented by researchers. Credit: Quaternary Environments and Humans Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent every weekday. For years, archeologists assumed the ancient Homo erectus population that lived on present-day Java existed in general isolation from nearby island relatives. However, a pair of fossilized skull fragments recently found off the Javanese coast are helping experts recontextualize the lives of the region’s H. erectus populations as they existed around 140,000 years ago. According to a study published May 15 in the journal Quaternary Environments and Humans, life for the Javanese H. erectus wasn’t always as lonely as we thought. Today, Indonesia consists of multiple islands between Asia and Australia, but that hasn’t always been the case. Beginning roughly 2.6 million years ago, the larger area has occasionally existed during periods of lower ocean levels as a larger, unified lowland landmass known as Sundaland. While H. erectus fossils have previously been found on Java itself, none were known to exist further outward in areas like the Madura Strait, which separates the islands of Madura from Central Java. A: The Sunda Shelf of Southeast Asia, with the Indonesian archipelago. Box indicates the position of map B. B: Eastern Java, the Madura Strait, the Solo River, Surabaya and other sites mentioned in the text. Box indicates position of map C. C: The Madura Strait north of Surabaya, with the sand extraction area and the BMS land reclamation. Map data: GEBCO and ALOS / Credit: Quaternary Environments and Humans That all changed thanks to over 176.5 million cubic feet of sand. The massive amount of sediment was dredged over 2014 to 2015 as part of an Indonesia land reclamation project, but it soon became clear that the sand also contained valuable historical remains. Scouring the material ultimately yielded around 6,000 fossil specimens from ancient fish, reptiles, and mammals–including the unexpected pair of H. erectus skull fragments. According to Harold Berghuis, study co-author and an archeologist at Leiden University in the Netherlands, their team’s discoveries are “truly unique.” “The fossils come from a drowned river valley, which filled up over time with river sand [dating to] approximately 140,000 years ago,” he said in an accompanying statement. Berghuis described that era as the “penultimate glacial period.” Earth’s Northern Hemisphere was so populated with glaciers, that the global sea level averaged nearly 1,100 feet lower than it does today. Because of this, Sundaland in the time of H. erectus greatly resembled the African savannah of today—largely dry grassland broken up by major rivers surrounded by narrow strips of forests. “Here they had water, shellfish, fish, edible plants, seeds and fruit all year round,” said Berghuis. Sundaland also featured a variety of animals, including multiple species of elephants, rhinos, and crocodiles. Strikingly, the bones the team found even have evidence of butchery by H. erectus. “Among our new finds are cut marks on the bones of water turtles and large numbers of broken bovid bones, which point to hunting and consumption of bone marrow,” Berghuis added. While this contrasts with earlier Javanese H. erectus populations, it had previously been documented in more modern human species who lived on the Asian mainland. According to the study’s authors, this indicates that Sundaland’s H. erectus may have learned those techniques from them. “This suggests there may have been contact between these hominin groups, or even genetic exchange,” theorized Berghuis.