An exciting discovery in paleoanthropology has expanded our understanding of prehistoric species that once roamed the Indonesian island of Java, particularly regarding the diversity of hominids that coexisted with Homo erectus approximately one million years ago. An international team of researchers, including scientists from the Senckenberg Research Institute, has documented a previously unrecognized fossil ape species, which was first described in 1950 by Gustav Heinrich Ralph von Koenigswald, the founder of Senckenberg’s paleoanthropological department. The species, known as Meganthropus palaeojavanicus, was originally believed to be an early human, but recent advancements in dental analysis have shown that it was not human, but rather a distinct species of ape that lived alongside Homo erectus. This significant breakthrough is detailed in a study published in Nature Ecology & Evolution.
The discovery is based on the examination of more than 200 fossilized teeth and jaw fragments found in Java, a region known for its rich hominid fossil record. The remains were largely attributed to Homo erectus, an early human species that became the first early human to be discovered outside of Europe. Homo erectus lived on Java during the Pleistocene epoch, roughly one million years ago. At this time, the island also hosted the ancestors of modern-day orangutans, creating a complex and diverse ecosystem of hominids and other primates. Until now, however, no evidence had confirmed the presence of other hominid species alongside Homo erectus.
As PD Dr. Ottmar Kullmer of the Senckenberg Research Institute explains, Homo erectus was long thought to be the sole hominid inhabiting Java during the Pleistocene. However, new findings suggest that at least three distinct hominid species coexisted with Homo erectus on the island, further expanding the diversity of prehistoric life on Java. The fossil teeth and jaw fragments that were studied belong to a species that was neither Homo erectus nor orangutans, but a previously unknown ape that cohabited with these species.
The breakthrough discovery centers on the re-examination of the fossil teeth first uncovered by von Koenigswald in 1941. These fossils have long been shrouded in controversy, as they were initially assigned to the enigmatic species Meganthropus palaeojavanicus, which von Koenigswald believed to be a prehistoric human species. However, this interpretation has been questioned for decades due to the lack of definitive evidence. Through the use of state-of-the-art micro-computer tomography and detailed analysis of the tooth enamel, the international team, led by Clément Zanolli of the University of Bordeaux, confirmed that the teeth did not belong to Homo erectus or any modern human ancestors, but to a different, unidentified species.
Zanolli, who led the study, explained that the micro-CT scans and enamel analysis showed significant differences in the structure of the teeth, particularly in the enamel thickness distribution and the morphology of the dentin cusps in the crowns. These characteristics set the species apart from Homo erectus and orangutans. The wear patterns observed on the molars of this species are consistent with those seen in modern-day orangutans, indicating that the species likely had a frugivorous diet, feeding primarily on fruits and other plant material, much like today’s orangutans.
This discovery sheds new light on the diet and lifestyle of Meganthropus. The wear patterns on its teeth suggest that this species consumed plant material from trees and other vegetation growing above ground. In contrast, Homo erectus, with its more complex and varied diet, likely relied on the ability to prepare and process food in a variety of ways. The team does not, however, have conclusive evidence as to whether Meganthropus’s diet contributed to its extinction, or whether competition with Homo erectus or other factors played a role in the ape’s disappearance.
The study’s findings also suggest that the diversity of hominids living on Java around one million years ago was much higher than previously thought. In addition to Homo erectus and Meganthropus, it is now believed that at least three additional genera of hominids may have inhabited the island. While the evidence for these other species is still being studied, it is clear that the prehistoric landscape of Java was far more complex than previously assumed, with a rich diversity of hominid and ape species coexisting in the forests.
There is also the possibility that another well-known prehistoric ape species, Gigantopithecus, may have been present on Java during this time, although definitive evidence for this remains lacking. Gigantopithecus, known for its enormous size, is believed to have lived in parts of Southeast Asia during the Pleistocene, and the discovery of fossils in nearby regions has raised the possibility that this giant ape might have shared the habitat with Homo erectus and the other hominid species on Java. However, more research and fossil discoveries are needed to confirm whether Gigantopithecus was indeed part of the island’s prehistoric ecosystem.
The study of ancient hominids is crucial for understanding the evolutionary relationships between early human species and their closest relatives. The discovery of Meganthropus palaeojavanicus and its implications for the diversity of hominids on Java adds a new layer of complexity to the evolutionary history of early humans. It suggests that the island was a hotspot of hominid diversity during the Pleistocene, with various species of humans and apes coexisting in close proximity.
This new understanding of the fossil record also has broader implications for the study of human evolution. It challenges previous assumptions about the exclusivity of human lineage and highlights the complex interplay between hominids and other primates during key periods in evolutionary history. As paleoanthropologists continue to analyze and interpret fossil remains, further discoveries like Meganthropus could continue to reshape our understanding of how early humans and their relatives evolved and interacted.
More information: Clément Zanolli et al. Evidence for increased hominid diversity in the Early to Middle Pleistocene of Indonesia, Nature Ecology & Evolution (2019). DOI: 10.1038/s41559-019-0860-z