Scientists have uncovered something incredible in central China that could completely upend our understanding of ancient humans. Researchers have determined that two skulls found in Lingjing, China back in 2007 and 2014 are between 100,000 and 130,000 years old, and they shed tremendous light on the relationship between humans and their Neanderthal relatives.

The paper, which was published in the journal Science, notes that the skulls have the ear canals of Neanderthals, but the low and flat brainpans of eastern Eurasians. They even resemble early modern Old World humans.

The skulls seem to belong to a totally new species that is not human or Neanderthal. Scientists think they may be Denisovans, which are an ancient human cousin that may have interbred with both humans and Neanderthals.

“The biological nature of the immediate predecessors of modern humans in eastern Eurasia has been poorly known from the human fossil record,” said Erik Trinkaus, a corresponding author for the study and professor of anthropology at Washington University in St. Louis, in a statement. “The discovery of these skulls of late archaic humans, from Xuchang, substantially increases our knowledge of these people.”

The abstract of the paper states; “Excavations in eastern Asia are yielding information on human evolution and migration. Li et al. analyzed two fossil human skulls from central China, dated to 100,000 to 130,000 years ago. The crania elucidate the pattern of human morphological evolution in eastern Eurasia. Some features are ancestral and similar to those of earlier eastern Eurasian humans, some are derived and shared with contemporaneous or later humans elsewhere, and some are closer to those of Neandertals. The analysis illuminates shared long-term trends in human adaptive biology and suggests the existence of interconnections between populations across Eurasia during the later Pleistocene.”