Humanity’s ancient history may be far more intricate than previously known, according to new findings that reveal an intriguing possibility: early Homo sapiens may have lived alongside another variety of large-brained ancient humans, which researchers call Homo juluensis.
The research, which involves hominin fossils associated with Eastern Asia’s Late Quaternary, could be poised to reshape our understanding of hominin evolution and suggests a far greater diversity amid distinctive early human populations, raising challenges to traditional evolutionary models.
Provocative Paleoanthropology
In recent decades, the discovery of new hominins—the taxonomic tribe consisting of humans and our ancient, now-extinct close relatives—has dramatically expanded the early human family tree. The discoveries involve a range of early hominin species, including past discoveries like Homo floresiensis, Homo luzonensis, and Homo longi, showcasing the significant morphological variability among early archaic human types.
Based on such discoveries, a new paper by Christopher J. Bae and co-author Xiujie Wu published in the journal Nature Communications lends new weight to the argument that human evolution is not a linear process but instead represents a complex interplay arising from early human migrations and genetic interchanges. Fundamentally, this apparent deeper evolutionary complexity suggests the need for a reevaluation of established views on evolution.
In their paper, Bae and Xiujie argue that paleoanthropology studies of the Late Quaternary have fallen behind in synthesizing morphological variability. However, recent fossil hominin discoveries in eastern Asia lend insights that may help researchers catch up, as mounting evidence shows that a much broader diversity of hominin forms appears to exist than currently recognized.
“It is now evident,” the researchers write in their study, “that morphological diversity among Late Quaternary hominin fossils from eastern Asia… is greater than we (and most researchers) expected.”
Based on new evidence, hominin dispersals and introgression events, where hybridization as a result of various groups’ interbreeding led to the mixing of genetic information between different groups, are more likely than a single replacement model, giving rise to the newly emerging evolutionary mosaic represented in ongoing discoveries of extinct hominin fossils.
Shifting Paradigms in Paleoanthropology
In early paleoanthropology studies, assigning new species names to hominin fossils had been standard practice. However, this began to change by the mid-20th century as scientists adopted more conservative approaches that involved grouping fossils into broader categories. Today, Bae and Xiujie write, researchers are more likely “to lump rather than split the Late Quaternary hominin fossils,” where the “lumpers” focus primarily on similarities between fossils, and “splitters” focus on their differences.
The conservative “lumping” of fossils may have given rise to Late Quaternary fossil designations in China, where most were categorized as either Homo erectus, transitional archaic H. sapiens, or modern H. sapiens. Out of these categorizations, human origin models like “multiregional evolution” were born, in which early humans in Asia directly evolved from local ancestors.
However, Bae and Xiujie argue that recent evidence suggests a hybrid model, where a combination of ongoing dispersals from Africa and local interbreeding seems to be a better fit for the emerging picture of ancient hominin diversity.
A pair of crucial discoveries that helped to shape this revised view on ancient human prehistory included the discoveries of Homo floresiensis in Indonesia in 2004 and Homo luzonensis in the Philippines in 2019. Added to this are even more recent additions like Homo longi, a variety recognized from analysis of a mysterious 146,000-year-old fossil skull known as “Dragon Man.”
Now, Bae and Xiujie present the idea of an entirely new early human species—Homo juluensis—of which the mysterious group known as the Denisovans may be a part.
“Most recently, after a detailed study of the Xujiayao and Xuchang fossils, we have added Homo juluensis to these discussions,” Bao and Xiujie write. “Importantly, we have assigned the enigmatic Denisova, along with the Xiahe and Penghu fossils, to H. juluensis,” determinations which the researchers say they based primarily on detailed analysis involving fossil hominin teeth.
In separate research published earlier this year, Xiujie and Bao had previously noted the striking appearance of a series of hominin fossils originally recovered from the Xujiayao site in northern China in the 1970s. “In fact,” the authors wrote, “the Xujiayao hominin fossils are quite unusual in their morphology,” emphasizing their large cranial capacity that featured a distinctive low and wide shaped skull. Additionally, the fossils possessed nasal characteristics resembling those of Neanderthals and “a mosaic of archaic and modern features” associated with the hominin’s large teeth.
“The Xujiayao hominin fossils have several basal East Asian traits despite their young geological age,” Bao and Xiujie wrote at the time, noting the presence of traits “that are not seen in either archaic or recent humans including other late Middle Pleistocene hominins from the region, except Xuchang, Penghu, Xiahe, and the Denisovans.”
In short, these enigmatic fossils appear to represent an entirely new variety of hominin which, based on its large cranial capacity, the researchers have given the name Juluren (formally Homo juluensis, meaning “large-headed people”), an enigmatic early hominin that Bao and Xiujie say once persisted throughout eastern Asia in the late Quaternary period.
A More Diverse Picture of Ancient Humans Emerges
Fundamentally, these provocative new findings and the diversity of the broader fossil record associated with eastern Asian hominins cannot be easily accounted for with conventional modern “linear” theories. Instead, they suggest that the emergence of modern humans resulted from more complex migration and interbreeding events in the ancient world.
Additionally, the accumulation of hominin fossil discoveries from eastern Asia could eventually lead researchers toward entirely new evolutionary models, which may help them better understand and characterize our ancient human ancestors.
“If anything, the eastern Asian record is prompting us to recognize just how complex human evolution is,” Bae and Xiujie conclude, adding that ongoing discoveries are forcing researchers “to revise and rethink our interpretations of various evolutionary models to better match the growing fossil record.”
The findings are certain to generate some controversy among the paleoanthropological research community, although Bae and Xiujie admit that proposing an entirely new variety of hominin had not been what they initially set out to accomplish with their research.
“Although we started this project several years ago, we did not expect being able to propose a new hominin (human ancestor) species and then to be able to organize the hominin fossils from Asia into different groups,” Bae recently said of the new findings.
“Ultimately,” he added, “this should help with science communication.”
The new paper, “Making sense of eastern Asian Late Quaternary hominin variability,” was published in Nature Communications.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.